DOCSLIB.ORG

The Influence of Amino Acids and Antimetabolites on Glycine Retention by Ehrlich Ascites Carcinoma Cells

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
The Influence of Amino Acids and Antimetabolites on Glycine Retention by Ehrlich Ascites Carcinoma Cells The Influence of Amino Acids and Antimetabolites on Glycine Retention by Ehrlich Ascites Carcinoma Cells R. M. JOHNSTONE* AND P. G. SCHOLEFIELDt (McGill-Montreal General Hospital Research Institute, 3619 University Street, Montreal, P.Q., Canada) The transport of biologically important sub- Many workers have shown that compounds stances across cell membranes has been studied in such as dinitrophenol, which interfere with the a wide variety of systems. For example, transport availability of energy in the form of adenosine of ions into and out of cells has long formed an triphosphate (ATP), also interfere with the integral part of studies in physiology (8), and it capacity of Ehrlich ascites cells to take up or to has been known since 1913 from the studies of Van transport amino acids (2, 10). However, it was felt Slyke and Meyer (20) that amino acids given to an that the information obtained from this approach animal appear in the tissues at concentrations could well be supplemented by a study of the which are higher than those of the surrounding kinetics of interaction of glycine with other amino medium. The transport of sugars and amino acids acids and with amino acid analogs. Christensen from the mucosal to the serosal side of the small et al. (3) and Tenenhouse and Quastel (17) have intestine in in vitro preparations has also been well already shown that certain amino acids inhibit established (6, 7, 18). the transport of other amino acids into Ehrlich The demonstration of the capacity of isolated ascites cells. Cohen and Monod (4), in their tumor cells to transport actively such substances studies of the displacement of thiogalactosides as ions, sugars, and amino acids (3, 5, 12) has in E. coli, concluded that such displacement is provided the means of more precise studies of this competitive and Tenenhouse and Quastel (17) have general phenomenon. Thus, the results of Chris- reached a similar conclusion with reference to tensen, Riggs, Fischer, and Palatine (3) show that amino acid interactions during the process of glycine may be concentrated in vitro by Ehrlich transport into Ehrlich ascites cells. It has also ascites carcinoma cells to the extent of more than been shown by Riggs, Coyne, and Christensen (14) twelvefold. Later results, obtained by Heinz and that amino acids, previously concentrated, may Mariani (10) using radioactive glycine, showed be displaced from Ehrlich ascites cells on addition that there were possibly three separate reactions of other amino acids. In the studies made by Riggs involved in the establishment of a steady state et al. (14), the amino acids were added at concen- concentration of glycine within the ascites cells. trations of 30-60 mmolar, and the final analyses 1. A specific mechanism for the transport of were made 2 or 3 hours later. A more detailed in- glycine (or other amino acids) across the cell vestigation of this phenomenon was undertaken to membrane. obtain information concerning the factors con- 2. A nonspecific influx and effiux dependent trolling the extent of glycine retention under only on the difference between the concentration various experimental conditions. of amino acid in the medium and that in the cell. Studies by Wiseman and Ghadially (19), in 8. An exchange of glycine in the cell with that which RD3 carcinoma cells were used, and by of the medium without any net flow of glycine, Birt and Hird (1), in which carrot slices were the exchange reaction occurring, according to utilized, showed that methionine is not well con- Heinz and Mariani (10), at a rate which is 5-6 centrated by these preparations but that it is an times as great as that of the rate of actual trans- effective inhibitor of the concentration of other port. amino acids such as glycine. In the present work, * Fellow of the National Cancer Institute of Canada. therefore, methionine has been used extensively t Research Associate of the National Cancer Institute of in studies of glycine retention by Ehrlich ascites Canada. cells. Further, the effects of the antimetabolites Received for publication April 6, 1959. studied on the incorporation of glycine into the 1140 Downloaded from cancerres.aacrjournals.org on September 30, 2021. © 1959 American Association for Cancer Research. JOHNSTONE AND SCHOLEFIELD--GlycineRetention by Ehrlich Ascites Cells 1141 alcohol-insoluble material (mainly into the pro- not more than 2 per cent of the remaining incuba- tein) has been determined in an attempt to esti- tion mixture. mate the specificity and nature of the effect of the Alcohol-soluble glycine.--The 2-ml. samples were inhibitors. In many cases the influence of added added directly to 3 ml. ice-cold calcium-free glucose was also investigated to assess the relative Krebs-Ringer solution, centrifuged, the super- effects of glycolysis and its consequences, such as natant removed, and the cells resuspended in a glycolytic ATP production, on the processes of further 5 ml. ice-cold calcium-free Krebs-Ring- uptake and incorporation of glycine. er solution. The suspension was again centri- fuged, the supernatant removed, and the interior MATERIALS AND METHODS of the tubes dried with paper tissues. To the Ascites cells.--The Ehrlich aseites cells were washed cells was then added 2 ml. 95 per cent harvested from CF1 mice 6 or 7 days after intra- ethanol, and a minimum period of 30 minutes was peritoneal transplantation. After a twenty-fold allowed for completion of the extraction of the dilution with ice-cold isotonic saline, the suspen- alcohol-soluble materials. After centrifugation, an sion was centrifuged for 20 seconds at maximum aliquot (300 gl.) of the supernatant was plated on speed in the six-place head of the International aluminum discs and the radioactivity assayed. A Clinical Model centrifuge. The supernatant, con- Geiger-Mtiller thin end-window tube and Baird taining most of the blood elements, was decanted Atomic "Abacus" Scaler were employed. No cor- and the procedure repeated twice. The packed-cell rection for self-absorption was necessary. volume was then determined by centrifugation of "Alcohol-insoluble" glycine.--The precipitate the loosely packed cells for 2 minutes, and finally remaining after extraction with 95 per cent ethanol the cells were resuspended in sufficient calcium- was washed twice with 5-ml. aliquots of 95 per free Krebs-Ringer solution to yield a 1 : 12 dilution. cent ethanol and once with 5 ml. acetone. The Ten ml. of such a suspension was used per 30 ml. residue was suspended in approximately 0.2 ml. incubation medium. acetone and quantitatively transferred with wash- The S-37 mouse tumor was obtained originally ings to aluminum discs. The precipitate was caused from the Roscoe B. Jackson Memorial Labora- to adhere to the plates by roughening the surface tories and the Ehrlich ascites carcinoma from Dr. and by addition of 0.2 ml. 50:50 (v/v) acetone : J. S. Colter. Both were maintained in the solid water just before complete evaporation of the ace- form by weekly subcutaneous injections and in the tone. The plates were then dried by means of a liquid form by weekly intraperitoneal injections. heat lamp. The dry weight did not exceed 1.5 rag/ At first there was difficulty in growing the S-37 sq cm and was quite consistent among plates in tumor in an ascitic form in CF1 mice, but it took any given experiment. The radioactivity of the readily in DBA mice, and the ascitie tumor thus plates was therefore measured as such, and no at- obtained took readily in CF1 mice. In the experi- tempt was made to apply any correction for self- ments reported here the S-37 ascites were har- absorption. Control experiments indicated that at vested from DBA mice. least 85 per cent of the radioactivity was present Incubation technic.--The incubation medium in the protein and that the specific activity was a calcium-free Krebs-Ringer phosphate solu- (counts/min/mg protein) was not appreciably tion. The cells were allowed to incubate in the altered on isolation of the protein by standard medium for 7 min. at 37 ~ C., and then sufficient methods. 60 mn glycine-l-C ~4 added to yield a final concen- tration of 2 mM. Approximately 10 gc. was added RESULTS to each 30 ml. of incubation medium. The incuba- The effects of methionine, leucine, and valine.-- tions were performed in Erlenmeyer flasks shaken The results reported by Christensen et al. (3) show aerobically in a Research Specialties Company that glycine entry into Ehrlich ascites carcinoma shaker at 37 ~ C. The rate of shaking varied ac- cells may be decreased by addition to the medium cording to the size of the flasks employed. Thus, a of other amino acids. Further, the results of Riggs shaking rate of 100/rain was needed with 25-ml. et al. (14) concerning the interaction of glycine, capacity flasks, but, to avoid clumping of the cells, tryptophan, and diaminobutyric acid show that this speed was reduced to 60 per minute when previously concentrated amino acids may be dis- 200-ml. capacity flasks were employed. Samples placed by other acids. The present results show (2 ml.) were removed for analysis at intervals as that the addition of many other amino acids leads required. Inhibitors were usually added after 30 to an efitux of glycine from cells which are in min. of incubation in the solid form whenever pos- equilibrium with a glycine-containing medium. sible or as a neutral solution with a total volume of Thus, on addition of sufficient methionine to yield Downloaded from cancerres.aacrjournals.org on September 30, 2021. © 1959 American Association for Cancer Research. 114~ Cancer Research Vol. 19, December, 1959 a final concentration of 5 raM, the glycine content tain a measure of the glycine incorporation.
Load more

Recommended publications
  • Effects of Single Amino Acid Deficiency on Mrna Translation Are Markedly
    www.nature.com/scientificreports OPEN Efects of single amino acid defciency on mRNA translation are markedly diferent for methionine Received: 12 December 2016 Accepted: 4 May 2018 versus leucine Published: xx xx xxxx Kevin M. Mazor, Leiming Dong, Yuanhui Mao, Robert V. Swanda, Shu-Bing Qian & Martha H. Stipanuk Although amino acids are known regulators of translation, the unique contributions of specifc amino acids are not well understood. We compared efects of culturing HEK293T cells in medium lacking either leucine, methionine, histidine, or arginine on eIF2 and 4EBP1 phosphorylation and measures of mRNA translation. Methionine starvation caused the most drastic decrease in translation as assessed by polysome formation, ribosome profling, and a measure of protein synthesis (puromycin-labeled polypeptides) but had no signifcant efect on eIF2 phosphorylation, 4EBP1 hyperphosphorylation or 4EBP1 binding to eIF4E. Leucine starvation suppressed polysome formation and was the only tested condition that caused a signifcant decrease in 4EBP1 phosphorylation or increase in 4EBP1 binding to eIF4E, but efects of leucine starvation were not replicated by overexpressing nonphosphorylatable 4EBP1. This suggests the binding of 4EBP1 to eIF4E may not by itself explain the suppression of mRNA translation under conditions of leucine starvation. Ribosome profling suggested that leucine deprivation may primarily inhibit ribosome loading, whereas methionine deprivation may primarily impair start site recognition. These data underscore our lack of a full
    [Show full text]
  • Relative Reaction Rates of the Amino Acids Cysteine, Methionine, and Histidine with Analogs of the Anti-Cancer Drug Cisplatin Cynthia A
    Western Kentucky University TopSCHOLAR® Honors College Capstone Experience/Thesis Honors College at WKU Projects 5-11-2015 Relative Reaction Rates of the Amino Acids Cysteine, Methionine, and Histidine with Analogs of the Anti-Cancer Drug Cisplatin Cynthia A. Tope Western Kentucky University, [email protected] Follow this and additional works at: http://digitalcommons.wku.edu/stu_hon_theses Part of the Medicinal-Pharmaceutical Chemistry Commons Recommended Citation Tope, Cynthia A., "Relative Reaction Rates of the Amino Acids Cysteine, Methionine, and Histidine with Analogs of the Anti-Cancer Drug Cisplatin" (2015). Honors College Capstone Experience/Thesis Projects. Paper 571. http://digitalcommons.wku.edu/stu_hon_theses/571 This Thesis is brought to you for free and open access by TopSCHOLAR®. It has been accepted for inclusion in Honors College Capstone Experience/ Thesis Projects by an authorized administrator of TopSCHOLAR®. For more information, please contact [email protected]. RELATIVE REACTION RATES OF THE AMINO ACIDS CYSTEINE, METHIONINE, AND HISTIDINE WITH ANALOGS OF THE ANTI-CANCER DRUG CISPLATIN A Capstone Experience/Thesis Project Presented in Partial Fulfillment of the Requirements for the Degree Bachelor of Science with Honors College Graduate Distinction at Western Kentucky University By: Cynthia A. Tope ***** Western Kentucky University 2015 CE/T Committee: Approved by: Professor Kevin Williams, Advisor _________________________ Professor Darwin Dahl Advisor Professor Lee Ann Smith Department of Chemistry Copyright: Cynthia A. Tope 2015 ABSTRACT We are studying the reaction of analogs of the anticancer drug cisplatin with amino acids that differ in size and shape. The reaction of cisplatin with proteins likely precedes reaction with DNA in the body, forming a variety of products that may be toxic to the human body.
    [Show full text]
  • L-Methionine
    October 24, 2011 Lisa Brines, Ph.D. National List Manager USDA/AMS/NOP, Standards Division 1400 Independence Ave. SW Room 2646-So., Ag Stop 0268 Washington, DC 20250-0268 RE: Petition for inclusion of L-Methionine on the National List at §205.605(b) as a synthetic non-agricultural substance allowed in or on processed infant formula products labeled as “organic” or “made with organic (specified ingredients)” with the annotation “for use only in infant formula based on isolated soy protein.” Dear Dr. Brines, The International Formula Council (IFC) is an association of manufacturers and marketers of formulated nutrition products (e.g., infant formulas and adult nutritionals) whose members are based predominantly in North America. IFC members support the American Academy of Pediatrics’ (AAP) position that breastfeeding is the preferred method of feeding infants. We also agree with the AAP that, for infants who do not receive breast milk, iron-fortified infant formula is the only safe and recommended alternative, IFC members are committed to providing infant formulas of the highest quality for those mothers who cannot or choose not to breastfeed, discontinue breastfeeding prior to one year or choose to supplement. This petition seeks to add L-Methionine to the National List to permit its addition as a nonagricultural ingredient in infant formula based on isolated soy protein. L-Methionine is an essential amino acid for humans of all ages. Amino acids are the building blocks of protein. An essential amino acid is one that must be provided in the foods in our diet since our bodies do not have the capability of producing enough of it for normal metabolism and growth.
    [Show full text]
  • Amino Acid Transport Pathways in the Small Intestine of the Neonatal Rat
    Pediat. Res. 6: 713-719 (1972) Amino acid neonate intestine transport, amino acid Amino Acid Transport Pathways in the Small Intestine of the Neonatal Rat J. F. FITZGERALD1431, S. REISER, AND P. A. CHRISTIANSEN Departments of Pediatrics, Medicine, and Biochemistry, and Gastrointestinal Research Laboratory, Indiana University School of Medicine and Veterans Administration Hospital, Indianapolis, Indiana, USA Extract The activity of amino acid transport pathways in the small intestine of the 2-day-old rat was investigated. Transport was determined by measuring the uptake of 1 mM con- centrations of various amino acids by intestinal segments after a 5- or 10-min incuba- tion and it was expressed as intracellular accumulation. The neutral amino acid transport pathway was well developed with intracellular accumulation values for leucine, isoleucine, valine, methionine, tryptophan, phenyl- alanine, tyrosine, and alanine ranging from 3.9-5.6 mM/5 min. The intracellular accumulation of the hydroxy-containing neutral amino acids threonine (essential) and serine (nonessential) were 2.7 mM/5 min, a value significantly lower than those of the other neutral amino acids. The accumulation of histidine was also well below the level for the other neutral amino acids (1.9 mM/5 min). The basic amino acid transport pathway was also operational with accumulation values for lysine, arginine and ornithine ranging from 1.7-2.0 mM/5 min. Accumulation of the essential amino acid lysine was not statistically different from that of nonessential ornithine. Ac- cumulation of aspartic and glutamic acid was only 0.24-0.28 mM/5 min indicating a very low activity of the acidic amino acid transport pathway.
    [Show full text]
  • Amino Acid Degradation
    BI/CH 422/622 OUTLINE: OUTLINE: Protein Degradation (Catabolism) Digestion Amino-Acid Degradation Inside of cells Protein turnover Dealing with the carbon Ubiquitin Fates of the 29 Activation-E1 Seven Families Conjugation-E2 nitrogen atoms in 20 1. ADENQ Ligation-E3 AA: Proteosome 2. RPH 9 ammonia oxidase Amino-Acid Degradation 18 transamination Ammonia 2 urea one-carbon metabolism free transamination-mechanism to know THF Urea Cycle – dealing with the nitrogen SAM 5 Steps Carbamoyl-phosphate synthetase 3. GSC Ornithine transcarbamylase PLP uses Arginino-succinate synthetase Arginino-succinase 4. MT – one carbon metabolism Arginase 5. FY – oxidase vs oxygenase Energetics Urea Bi-cycle 6. KW – Urea Cycle – dealing with the nitrogen 7. BCAA – VIL Feeding the Urea Cycle Glucose-Alanine Cycle Convergence with Fatty acid-odd chain Free Ammonia Overview Glutamine Glutamate dehydrogenase Overall energetics Amino Acid A. Concepts 1. ConvergentDegradation 2. ketogenic/glucogenic 3. Reactions seen before The SEVEN (7) Families B. Transaminase (A,D,E) / Deaminase (Q,N) Family C. Related to biosynthesis (R,P,H; C,G,S; M,T) 1.Glu Family a. Introduce oxidases/oxygenases b. Introduce one-carbon metabolism (1C) 2.Pyruvate Family a. PLP reactions 3. a-Ketobutyric Family (M,T) a. 1-C metabolism D. Dedicated 1. Aromatic Family (F,Y) a. oxidases/oxygenases 2. a-Ketoadipic Family (K,W) 3. Branched-chain Family (V,I,L) E. Convergence with Fatty Acids: propionyl-CoA 29 N 1 Amino Acid Degradation • Intermediates of the central metabolic pathway • Some amino acids result in more than one intermediate. • Ketogenic amino acids can be converted to ketone bodies.
    [Show full text]
  • Where Metal Ions Bind in Proteins (Metafloprotein/Protein Structure/Hydrophobicity Contrast Function) MASON M
    Proc. Nadl. Acad. Sci. USA Vol. 87, pp. 5648-5652, August 1990 Biophysics Where metal ions bind in proteins (metafloprotein/protein structure/hydrophobicity contrast function) MASON M. YAMASHITA*t, LAURA WESSON*, GEORGE EISENMANt, AND DAVID EISENBERG*§ *Molecular Biology Institute and Department of Chemistry and Biochemistry, and *Department of Physiology, University of California, Los Angeles, CA 90024 Contributed by David Eisenberg, May 14, 1990 ABSTRACT The environments of metal ions (Li', Na', K+, Ag+, Cs+, Mg2+, Ca2+, Mn2+9 Cu2+, Zn2+) in proteins and other metal-host molecules have been examined. Regard- .. 0.00- ______ less ofthe metal and its precise pattern ofligation to the protein, there is a common qualitative feature to the bind site: the metal is ligated by a shell of hydrophilic atomic groups (con- E -0.01 Zn2+ taining oxygen, nitrogen, or sulfur atoms) and this hydrophilic shell is embedded within a larger shell of hydrophobic atomic - -0.02 groups (containing carbon atoms). That is, metals bind at centers of high hydrophobicity contrast. This qualitative ob- servation can be described analytically by the hydrophobicity 0 2 4 6 8 10 contrast function, C, evaluated from the structure. This func- tion is large and positive for a sphere of hydrophilic atomic 0.01 groups (characterized by atomic salvation parameters, Aar, having values < 0) at the center of a larger sphere of hydro- phobic atomic groups (characterized by Aor > 0). In the 23 0.00. metal-binding molecules we have examined, the maximum values of the contrast function lie near to observed metal binding sites. This suggests that the hydrophobicity contrast function may be useful for locating, characterizing, and de- - -0.01 signing metal binding sites in proteins.
    [Show full text]
  • Acrylamide Is Formed in the Maillard Reaction
    brief communications *Institute for Zoo and Wildlife Research, Research Unit, 33612 Cestas cedex, France 185 °C, no acrylamide was detected (detec- Department of Evolutionary Genetics, #Hudson River Foundation for Science and tion limit, 0.5 mg mol11). Glutamine and 10252 Berlin, Germany Environmental Research, New York, aspartic acid gave only trace quantities of e-mail: [email protected] New York 10011, USA acrylamide (0.5–1 mg mol11). †Institute of Zoology, University of Rostock, 1. Ludwig, A., May, B., Debus, L. & Jenneckens, I. Genetics 156, When a dry mixture of asparagine and 18051 Rostock, Germany 1933–1947 (2000). glucose was reacted at 185 °C (that is, ‡Department of Environmental Medicine, 2. King, T. L., Lubinski, B. A. & Spidle, A. P. Conserv. Genet. 2, without buffer solution), only 25 mg mol11 103–119 (2001). New York University School of Medicine, Tuxedo, 3. Brown, J. T., Beckenbach, A. T. & Smith, M. J. Mol. Biol. Evol. acrylamide was formed. Although the dry New York 10987, USA 10, 326–341 (1993). reaction is a realistic system with which to §German Archaeological Institute, 4. Magnin, E. Le Naturaliste Canadien 91, 5–20 (1964). 5. Artyukhin, E. & Vecsei, P. J. Appl. Ichthyol. 15, 35–37 (1999). simulate the later stages of baking and toast- Eurasian Division, 14195 Berlin, Germany 6. Borodin, N. Trans. Am. Fish. Soc. 55, 184–190 (1925). ing of food, it is less efficient because the ||Institute for Animal Breeding and Genetics, 7. Quantz, H. Mitt. Dt. Seefischerei-Vereins 19, 176–204 (1903). reactants are incompletely mixed in the Supplementary information accompanies this communication on University of Göttingen, 37075 Göttingen, Germany Nature’s website.
    [Show full text]
  • Dietary Interrelationships Among Arginine, Methionine, and Lysine In
    Downloaded from https://www.cambridge.org/core British Journal of Nutrition (2002), 88, 655–660 DOI: 10.1079/BJN2002732 q The Authors 2002 Dietary interrelationships among arginine, methionine, and lysine in . IP address: young broiler chicks 170.106.202.226 M. Chamruspollert, G. M. Pesti* and R. I. Bakalli Department of Poultry Science, The University of Georgia, Athens, Georgia 30602-2772, USA (Received 5 September 2001 – Revised 30 July 2002 – Accepted 11 August 2002) , on 26 Sep 2021 at 15:14:48 Since excess dietary lysine (Lys) can increase the chick’s arginine (Arg) requirement and excess Arg can increase the chick’s methionine (Met) requirement, experiments were conducted to test the hypothesis that responses to dietary Lys and Met are also interrelated. Day-old Ross £ Ross chicks were fed a maize–soyabean meal-based diet supplemented with four levels of , subject to the Cambridge Core terms of use, available at L-Arg (0, 5, 10 or 20 g/kg), factorially arranged with four levels of supplemental DL-Met (0, 1, 2 or 3 g/kg). Three replicate pens of ten chicks each were randomly assigned to each treatment and fed for 14 d. An increase in Arg in the diet caused growth and feed-intake depression (P¼0·0001), but increasing Met in the diet enhanced growth and feed intake (P¼0·0001). Arg toxicity was dependent on the Met level of the diet (Arg £ Met interaction; P¼0·0153). Experiment 2 was conducted to study interrelationships among Arg, Met, and Lys. Eight treatments were factorially combined: two levels of supplemental L-Arg (0 or 10 g/kg), two levels of supplemental DL-Met (0 or 2 g/kg), and two levels of supplemental L-Lys (0 or 6 g/kg).
    [Show full text]
  • Metabolism of Methionine in the Newborn Infant: Response to the Parenteral and Enteral Administration of Nutrients
    0031-3998/08/6404-0381 Vol. 64, No. 4, 2008 PEDIATRIC RESEARCH Printed in U.S.A. Copyright © 2008 International Pediatric Research Foundation, Inc. Metabolism of Methionine in the Newborn Infant: Response to the Parenteral and Enteral Administration of Nutrients BIJU THOMAS, LOURDES L. GRUCA, CAROLE BENNETT, PRABHU S. PARIMI, RICHARD W. HANSON, AND SATISH C. KALHAN Department of Pediatrics [B.T., P.S.P.], MetroHealth Medical Center, Cleveland, Ohio 44109, Department of Medicine [L.L.G., C.B., R.W.H., S.C.K.], Cleveland Clinic Lerner College of Medicine, Cleveland, Ohio 44195, Department of Biochemistry [R.W.H.], Case Western Reserve University, Cleveland, Ohio 44106 ABSTRACT: The rates of transmethylation and transsulfuration of birth and of nutrient interventions on the transsulfuration of methionine were quantified using [1-13C]methionine and methionine is unknown. 2 [C H3]methionine tracers in newborn infants born at term gestation The synthesis of cysteine from homocysteine and serine is and in prematurely born low birth weight infants. Whole body rate of regulated by an individual’s nutrient state and by the relative 2 protein breakdown was also measured using [ H5]phenylalanine. The concentration of insulin, glucagon and adrenal corticosteroids response to enteral formula feeding and parenteral nutrition was (10–12). Insulin has a repressive effect on hepatic CGL and on examined in full term and prematurely born babies, respectively. The cystathionine ␤ synthase (CBS), whereas glucagon and glu- relative rates of appearance of methionine and phenylalanine were cocorticoids increase the hepatic activity of these enzymes. comparable to the amino acid composition of mixed body proteins.
    [Show full text]
  • Plasma Concentrations and Intakes of Amino Acids in Male Meat-Eaters, fish-Eaters, Vegetarians and Vegans: a Cross-Sectional Analysis in the EPIC-Oxford Cohort
    European Journal of Clinical Nutrition (2016) 70, 306–312 OPEN © 2016 Macmillan Publishers Limited All rights reserved 0954-3007/16 www.nature.com/ejcn ORIGINAL ARTICLE Plasma concentrations and intakes of amino acids in male meat-eaters, fish-eaters, vegetarians and vegans: a cross-sectional analysis in the EPIC-Oxford cohort JA Schmidt1, S Rinaldi2, A Scalbert2, P Ferrari2, D Achaintre2, MJ Gunter3, PN Appleby1, TJ Key1 and RC Travis1 BACKGROUND/OBJECTIVES: We aimed to investigate the differences in plasma concentrations and in intakes of amino acids between male meat-eaters, fish-eaters, vegetarians and vegans in the Oxford arm of the European Prospective Investigation into Cancer and Nutrition. SUBJECTS/METHODS: This cross-sectional analysis included 392 men, aged 30–49 years. Plasma amino acid concentrations were measured with a targeted metabolomic approach using mass spectrometry, and dietary intake was assessed using a food frequency questionnaire. Differences between diet groups in mean plasma concentrations and intakes of amino acids were examined using analysis of variance, controlling for potential confounding factors and multiple testing. RESULTS: In plasma, concentrations of 6 out of 21 amino acids varied significantly by diet group, with differences of − 13% to +16% between meat-eaters and vegans. Concentrations of methionine, tryptophan and tyrosine were highest in fish-eaters and vegetarians, followed by meat-eaters, and lowest in vegans. A broadly similar pattern was seen for lysine, whereas alanine concentration was highest in fish-eaters and lowest in meat-eaters. For glycine, vegans had the highest concentration and meat-eaters the lowest. Intakes of all 18 dietary amino acids differed by diet group; for the majority of these, intake was highest in meat-eaters followed by fish-eaters, then vegetarians and lowest in vegans (up to 47% lower than in meat-eaters).
    [Show full text]
  • 24Amino Acids, Peptides, and Proteins
    WADEMC24_1153-1199hr.qxp 16-12-2008 14:15 Page 1153 CHAPTER COOϪ a -h eli AMINO ACIDS, x ϩ PEPTIDES, AND NH3 PROTEINS Proteins are the most abundant organic molecules 24-1 in animals, playing important roles in all aspects of cell structure and function. Proteins are biopolymers of Introduction 24A-amino acids, so named because the amino group is bonded to the a carbon atom, next to the carbonyl group. The physical and chemical properties of a protein are determined by its constituent amino acids. The individual amino acid subunits are joined by amide linkages called peptide bonds. Figure 24-1 shows the general structure of an a-amino acid and a protein. α carbon atom O H2N CH C OH α-amino group R side chain an α-amino acid O O O O O H2N CH C OH H2N CH C OH H2N CH C OH H2N CH C OH H2N CH C OH CH3 CH2OH H CH2SH CH(CH3)2 alanine serine glycine cysteine valine several individual amino acids peptide bonds O O O O O NH CH C NH CH C NH CH C NH CH C NH CH C CH3 CH2OH H CH2SH CH(CH3)2 a short section of a protein a FIGURE 24-1 Structure of a general protein and its constituent amino acids. The amino acids are joined by amide linkages called peptide bonds. 1153 WADEMC24_1153-1199hr.qxp 16-12-2008 14:15 Page 1154 1154 CHAPTER 24 Amino Acids, Peptides, and Proteins TABLE 24-1 Examples of Protein Functions Class of Protein Example Function of Example structural proteins collagen, keratin strengthen tendons, skin, hair, nails enzymes DNA polymerase replicates and repairs DNA transport proteins hemoglobin transports O2 to the cells contractile proteins actin, myosin cause contraction of muscles protective proteins antibodies complex with foreign proteins hormones insulin regulates glucose metabolism toxins snake venoms incapacitate prey Proteins have an amazing range of structural and catalytic properties as a result of their varying amino acid composition.
    [Show full text]
  • The Effects of Dietary Histidine, Methionine and Homocystine on Vitamin B,, and Folate Levels in Rat Liver
    Downloaded from 299 https://www.cambridge.org/core The effects of dietary histidine, methionine and homocystine on vitamin B,, and folate levels in rat liver BY D. L. WILLIAMS AND G. H. SPRAY Nuftield Department of Clinical Medicine, Rndclaze InJirmary, Oxford OX2 6HE . IP address: (Received 12 May 1975 -Accepted 4 Novembw 1975) 170.106.202.8 I. L-histidine (20 g/kg) added to vitamin Bl,-deficient and cyanocobalamin-supplemented diets based on soya-bean flour reduced the growth of rats given the vitamin B,,-deficient diet but stimulated growth of rats given the cyanocobalamin-supplemented diet. Liver weight (g/kg body-weight) increased, but the protein content of the livers decreased, in rats given , on histidine supplements. The histidine was associated with significantly higher folate con- 28 Sep 2021 at 17:30:18 centrations in the livers of cyanocobalamin-supplemented rats. 2. Vitamin B1,-deficient and cyanocobalamin-supplementedrats were given diets based on a mixture of amino acids that was balanced apart from methionine, which was added in various amounts, and with the addition of homocystine. The only vitamin B,,-deficient rats which had reasonable gains in weight were those receiving a diet containing 8 g L-methionine/kg. The remainder, particularly those given diets containing only homocystine, had little or no increase in weight. All the cyanocobalamin-supplemented rats gained weight; those given diets containing 2 and 8 g L-methionine/kg, or 8 g homocystine/kg, had the highest gains. , subject to the Cambridge Core terms of use, available at 3. There was a tendency for a higher concentration of either methionine or homocystine in the diet to be associated with higher concentrations of both folate and vitamin Biz in the livers.
    [Show full text]