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A Guardian of the Development of Diabetic Retinopathy
Diabetes Volume 67, April 2018 745 Sirt1: A Guardian of the Development of Diabetic Retinopathy Manish Mishra, Arul J. Duraisamy, and Renu A. Kowluru Diabetes 2018;67:745–754 | https://doi.org/10.2337/db17-0996 Diabetic retinopathy is a multifactorial disease, and the molecular mechanism of the development of diabetic reti- exact mechanism of its pathogenesis remains obscure. nopathy remains to be established. Sirtuin 1 (Sirt1), a multifunctional deacetylase, is impli- Sirtuin 1 (Sirt1), a member of the silent information cated in the regulation of many cellular functions and in regulator 2 family, is a class III histone deacetylase that gene transcription, and retinal Sirt1 is inhibited in di- interacts with target proteins and regulates many cellular abetes. Our aim was to determine the role of Sirt1 in the functions including cell proliferation, apoptosis, and inflam- development of diabetic retinopathy and to elucidate the matory responses (6–8). Sirt1 is mainly a nuclear protein, Sirt1 molecular mechanism of its downregulation. Using - and its activity depends on cellular NAD availability (9). It is overexpressing mice that were diabetic for 8 months, Sirt1 expressed throughout the retina, and upregulation of COMPLICATIONS structural, functional, and metabolic abnormalities were protects against various ocular diseases including retinal investigated in vascular and neuronal retina. The role of degeneration, cataract, and optic neuritis (10). Our previous epigenetics in Sirt1 transcriptional suppression was inves- work has shown that Sirt1 expression and activity are de- tigated in retinal microvessels. Compared with diabetic wild-type mice, retinal vasculature from diabetic Sirt1 mice creased in the retina and its capillary cells in diabetes (11). -
Cytosine-Rich
Proc. Natl. Acad. Sci. USA Vol. 93, pp. 12116-12121, October 1996 Chemistry Inter-strand C-H 0 hydrogen bonds stabilizing four-stranded intercalated molecules: Stereoelectronic effects of 04' in cytosine-rich DNA (base-ribose stacking/sugar pucker/x-ray crystallography) IMRE BERGERt, MARTIN EGLIt, AND ALEXANDER RICHt tDepartment of Biology, Massachusetts Institute of Technology, Cambridge, MA 02139; and tDepartment of Molecular Pharmacology and Biological Chemistry, Northwestern University Medical School, 303 East Chicago Avenue, Chicago, IL 60611-3008 Contributed by Alexander Rich, August 19, 1996 ABSTRACT DNA fragments with stretches of cytosine matic cytosine ring systems from intercalated duplexes (Fig. 1A). residues can fold into four-stranded structures in which two Second, unusually close intermolecular contacts between sugar- parallel duplexes, held together by hemiprotonated phosphate backbones in the narrow grooves are observed, with cytosine-cytosine+ (C C+) base pairs, intercalate into each inter-strand phosphorus-phosphorus distances as close as 5.9 A other with opposite polarity. The structural details of this (5), presumably resulting in unfavorable electrostatic repulsion if intercalated DNA quadruplex have been assessed by solution not shielded by cations or bridging water molecules. NMR and single crystal x-ray diffraction studies of cytosine- The close contacts between pairs of antiparallel sugar- rich sequences, including those present in metazoan telo- phosphate backbones from the two interdigitated duplexes are meres. A conserved feature of these structures is the absence a unique characteristic of four-stranded intercalated DNA. of stabilizing stacking interactions between the aromatic ring Indeed, the unusually strong nuclear overhauser effect signals systems of adjacent C-C+ base pairs from intercalated du- between inter-strand sugar Hi' protons and Hi' and H4' plexes. -
REDUCTION of PURINE CONTENT in COMMONLY CONSUMED MEAT PRODUCTS THROUGH RINSING and COOKING by Anna Ellington (Under the Directio
REDUCTION OF PURINE CONTENT IN COMMONLY CONSUMED MEAT PRODUCTS THROUGH RINSING AND COOKING by Anna Ellington (Under the direction of Yen-Con Hung) Abstract The commonly consumed meat products ground beef, ground turkey, and bacon were analyzed for purine content before and after a rinsing treatment. The rinsing treatment involved rinsing the meat samples using a wrist shaker in 5:1 ratio water: sample for 2 or 5 minutes then draining or centrifuging to remove water. The total purine content of 25% fat ground beef significantly decreased (p<0.05) from 8.58 mg/g protein to a range of 5.17-7.26 mg/g protein after rinsing treatments. After rinsing and cooking an even greater decrease was seen ranging from 4.59-6.32 mg/g protein. The total purine content of 7% fat ground beef significantly decreased from 7.80 mg/g protein to a range of 5.07-5.59 mg/g protein after rinsing treatments. A greater reduction was seen after rinsing and cooking in the range of 4.38-5.52 mg/g protein. Ground turkey samples showed no significant changes after rinsing, but significant decreases were seen after rinsing and cooking. Bacon samples showed significant decreases from 6.06 mg/g protein to 4.72 and 4.49 after 2 and 5 minute rinsing and to 4.53 and 4.68 mg/g protein after 2 and 5 minute rinsing and cooking. Overall, this study showed that rinsing foods in water effectively reduces total purine content and subsequent cooking after rinsing results in an even greater reduction of total purine content. -
Chapter 23 Nucleic Acids
7-9/99 Neuman Chapter 23 Chapter 23 Nucleic Acids from Organic Chemistry by Robert C. Neuman, Jr. Professor of Chemistry, emeritus University of California, Riverside [email protected] <http://web.chem.ucsb.edu/~neuman/orgchembyneuman/> Chapter Outline of the Book ************************************************************************************** I. Foundations 1. Organic Molecules and Chemical Bonding 2. Alkanes and Cycloalkanes 3. Haloalkanes, Alcohols, Ethers, and Amines 4. Stereochemistry 5. Organic Spectrometry II. Reactions, Mechanisms, Multiple Bonds 6. Organic Reactions *(Not yet Posted) 7. Reactions of Haloalkanes, Alcohols, and Amines. Nucleophilic Substitution 8. Alkenes and Alkynes 9. Formation of Alkenes and Alkynes. Elimination Reactions 10. Alkenes and Alkynes. Addition Reactions 11. Free Radical Addition and Substitution Reactions III. Conjugation, Electronic Effects, Carbonyl Groups 12. Conjugated and Aromatic Molecules 13. Carbonyl Compounds. Ketones, Aldehydes, and Carboxylic Acids 14. Substituent Effects 15. Carbonyl Compounds. Esters, Amides, and Related Molecules IV. Carbonyl and Pericyclic Reactions and Mechanisms 16. Carbonyl Compounds. Addition and Substitution Reactions 17. Oxidation and Reduction Reactions 18. Reactions of Enolate Ions and Enols 19. Cyclization and Pericyclic Reactions *(Not yet Posted) V. Bioorganic Compounds 20. Carbohydrates 21. Lipids 22. Peptides, Proteins, and α−Amino Acids 23. Nucleic Acids ************************************************************************************** -
Human Hypoxanthine (Guanine) Phosphoribosyltransferase: An
Proc. NatL Acad. Sci. USA Vol. 80, pp. 870-873, Febriary 1983 Medical Sciences Human hypoxanthine (guanine) phosphoribosyltransferase: An amino acid substitution in a mutant form of the enzyme isolated from a patient with gout (reverse-phase HPLC/peptide mapping/mutant enzyme) JAMES M. WILSON*t, GEORGE E. TARRt, AND WILLIAM N. KELLEY*t Departments of *Internal Medicine and tBiological Chemistry, University of Michigan Medical School, Ann Arbor, Michigan 48109 Communicated by James B. Wyngaarden, November 3, 1982 ABSTRACT We have investigated the molecular basis for a tration ofenzyme protein. in both erythrocytes (3) and lympho- deficiency ofthe enzyme hypoxanthine (guanine) phosphoribosyl- blasts (4); (ii) a normal Vm., a normal Km for 5-phosphoribosyl- transferase (HPRT; IMP:pyrophosphate-phosphoribosyltransfer- 1-pyrophosphate, and a 5-fold increased Km for hypoxanthine ase, EC 2.4.2.8) in a patient with a severe form of gout. We re-. (unpublished data); (iii) a normal isoelectric point (3, 4) and ported in previous studies the isolation of a unique structural migration during nondenaturing polyacrylamide gel electro- variant of HPRT from this patient's erythrocytes and cultured phoresis (4); and (iv) -an apparently smaller subunit molecular lymphoblasts. This enzyme variant, which is called HPRTOnd0., weight as evidenced by an increased mobility during Na- is characterized by a decreased concentration of HPRT protein DodSO4/polyacrylamide gel electrophoresis (3, 4). in erythrocytes and lymphoblasts, a normal Vm.., a 5-fold in- Our study ofthe tryptic peptides and amino acid composition creased Km for hypoxanthine, a normal isoelectric point, and an of apparently smaller subunit molecular weight. Comparative pep- HPRTLondon revealed a single amino acid substitution (Ser tide mapping-experiments revealed a single abnormal tryptic pep- Leu) at position 109. -
Gout: a Low-Purine Diet Makes a Difference
Patient HANDOUT Gout: A Low-Purine Diet Makes a Difference Gout occurs when high levels of uric acid in your blood cause crystals to form and build up around a joint. Your body produces uric acid when it breaks down purines. Purines occur naturally in your body, but you also get them from certain foods and drinks. By following a low-purine diet, you can help your body control the production of uric acid and lower your chances of having another gout attack. Purines are found in many healthy foods and drinks. The purpose of a low-purine diet is to lower the amount of purine that you consume each day. Avoid Beer High-Purine Foods Organ meats (e.g., liver, kidneys), bacon, veal, venison Anchovies, sardines, herring, scallops, mackerel Gravy (purines leach out of the meat during cooking so gravy made from drippings has a higher concentration of purines) Limit Moderate- Chicken, beef, pork, duck, crab, lobster, oysters, shrimp : 4-6 oz daily Purine Foods Liquor: Limit alcohol intake. There is evidence that risk of gout attack is directly related to level of alcohol consumption What Other Dietary Changes Can Help? • Choose low-fat or fat-free dairy products. Studies show that low- or non-fat milk and yogurt help reduce the chances of having a gout attack. • Drink plenty of fluids (especially water) which can help remove uric acid from your body. Avoid drinks sweetened with fructose such as soft drinks. • Eat more non-meat proteins such as legumes, nuts, seeds and eggs. • Eat more whole grains and fruits and vegetables and less refined carbohydrates, such as white bread and cakes. -
A Previously Undescribed Pathway for Pyrimidine Catabolism
A previously undescribed pathway for pyrimidine catabolism Kevin D. Loh*†, Prasad Gyaneshwar*‡, Eirene Markenscoff Papadimitriou*§, Rebecca Fong*, Kwang-Seo Kim*, Rebecca Parales¶, Zhongrui Zhouʈ, William Inwood*, and Sydney Kustu*,** *Department of Plant and Microbial Biology, 111 Koshland Hall, University of California, Berkeley, CA 94720-3102; ¶Section of Microbiology, 1 Shields Avenue, University of California, Davis, CA 95616; and ʈCollege of Chemistry, 8 Lewis Hall, University of California, Berkeley, CA 94720-1460 Contributed by Sydney Kustu, January 19, 2006 The b1012 operon of Escherichia coli K-12, which is composed of tive N sources. Here we present evidence that the b1012 operon seven unidentified ORFs, is one of the most highly expressed codes for proteins that constitute a previously undescribed operons under control of nitrogen regulatory protein C. Examina- pathway for pyrimidine degradation and thereby confirm the tion of strains with lesions in this operon on Biolog Phenotype view of Simaga and Kos (8, 9) that E. coli K-12 does not use either MicroArray (PM3) plates and subsequent growth tests indicated of the known pathways. that they failed to use uridine or uracil as the sole nitrogen source and that the parental strain could use them at room temperature Results but not at 37°C. A strain carrying an ntrB(Con) mutation, which Behavior on Biolog Phenotype MicroArray Plates. We tested our elevates transcription of genes under nitrogen regulatory protein parental strain NCM3722 and strains with mini Tn5 insertions in C control, could also grow on thymidine as the sole nitrogen several genes of the b1012 operon on Biolog (Hayward, CA) source, whereas strains with lesions in the b1012 operon could not. -
Pdfs/0551.Pdf
1 Structures of the Molecular Components in DNA and RNA with Bond Lengths Interpreted as Sums of Atomic Covalent Radii Raji Heyrovská* Institute of Biophysics of the Academy of Sciences of the Czech Republic, Královopolská 135, 61265 Brno, Czech Republic. *E-mail: [email protected] Abstract: The author has found recently that the lengths of chemical bonds are sums of the covalent and or ionic radii of the relevant atoms constituting the bonds, whether they are completely or partially covalent or ionic. This finding has been tested here for the skeletal bond lengths in the molecular constituents of nucleic acids, adenine, thymine, guanine, cytosine, uracil, ribose, deoxyribose and phosphoric acid. On collecting the existing data and comparing them graphically with the sums of the appropriate covalent radii of C, N, O, H and P, it is found that there is a linear dependence with unit slope and zero intercept. This shows that the bond lengths in the above molecules can be interpreted as sums of the relevant atomic covalent radii. Based on this, the author has presented here (for the first time) the atomic structures of the above molecules and of DNA and RNA nucleotides with Watson-Crick base pairs, which satisfy the known dimensions. INTRODUCTION Following the exciting discovery [1] of the molecular structure of nucleic acids, the question of the skeletal bond lengths in the molecules constituting DNA and RNA has continued to be of interest. The author was enthused to undertake this work by the recent findings [2a, b] that the length of the chemical bond between any two atoms or ions is, in general, the sum of the radii of 2 the atoms and or ions constituting the bond. -
Effects of Allopurinol and Oxipurinol on Purine Synthesis in Cultured Human Cells
Effects of allopurinol and oxipurinol on purine synthesis in cultured human cells William N. Kelley, James B. Wyngaarden J Clin Invest. 1970;49(3):602-609. https://doi.org/10.1172/JCI106271. Research Article In the present study we have examined the effects of allopurinol and oxipurinol on thed e novo synthesis of purines in cultured human fibroblasts. Allopurinol inhibits de novo purine synthesis in the absence of xanthine oxidase. Inhibition at lower concentrations of the drug requires the presence of hypoxanthine-guanine phosphoribosyltransferase as it does in vivo. Although this suggests that the inhibitory effect of allopurinol at least at the lower concentrations tested is a consequence of its conversion to the ribonucleotide form in human cells, the nucleotide derivative could not be demonstrated. Several possible indirect consequences of such a conversion were also sought. There was no evidence that allopurinol was further utilized in the synthesis of nucleic acids in these cultured human cells and no effect of either allopurinol or oxipurinol on the long-term survival of human cells in vitro could be demonstrated. At higher concentrations, both allopurinol and oxipurinol inhibit the early steps ofd e novo purine synthesis in the absence of either xanthine oxidase or hypoxanthine-guanine phosphoribosyltransferase. This indicates that at higher drug concentrations, inhibition is occurring by some mechanism other than those previously postulated. Find the latest version: https://jci.me/106271/pdf Effects of Allopurinol and Oxipurinol on Purine Synthesis in Cultured Human Cells WILLIAM N. KELLEY and JAMES B. WYNGAARDEN From the Division of Metabolic and Genetic Diseases, Departments of Medicine and Biochemistry, Duke University Medical Center, Durham, North Carolina 27706 A B S TR A C T In the present study we have examined the de novo synthesis of purines in many patients. -
Xanthine/Hypoxanthine Assay Kit
Product Manual Xanthine/Hypoxanthine Assay Kit Catalog Number MET-5150 100 assays FOR RESEARCH USE ONLY Not for use in diagnostic procedures Introduction Xanthine and hypoxanthine are naturally occurring purine derivatives. Xanthine is created from guanine by guanine deaminase, from hypoxanthine by xanthine oxidoreductase, and from xanthosine by purine nucleoside phosphorylase. Xanthine is used as a building block for human and animal drug medications, and is an ingredient in pesticides. In vitro, xanthine and related derivatives act as competitive nonselective phosphodiesterase inhibitors, raising intracellular cAMP, activating Protein Kinase A (PKA), inhibiting tumor necrosis factor alpha (TNF-α) as well as and leukotriene synthesis. Furthermore, xanthines can reduce levels of inflammation and act as nonselective adenosine receptor antagonists. Hypoxanthine is sometimes found in nucleic acids such as in the anticodon of tRNA in the form of its nucleoside inosine. Hypoxanthine is a necessary part of certain cell, bacteria, and parasitic cultures as a substrate and source of nitrogen. For example, hypoxanthine is often a necessary component in malaria parasite cultures, since Plasmodium falciparum needs hypoxanthine to make nucleic acids as well as to support energy metabolism. Recently NASA studies with meteorites found on Earth supported the idea that hypoxanthine and related organic molecules can be formed extraterrestrially. Hypoxanthine can form as a spontaneous deamination product of adenine. Because of its similar structure to guanine, the resulting hypoxanthine base can lead to an error in DNA transcription/replication, as it base pairs with cytosine. Hypoxanthine is typically removed from DNA by base excision repair and is initiated by N- methylpurine glycosylase (MPG). -
Purine Metabolism in the Protozoan Parasite Eimeria Tenella (Hypoxanthine-Xanthine-Guanine Phosphoribosyltransferase/GMP-Agarose Affinity Column/Alopurinol) C
Proc. NatL Acad. Sci. USA Vol. 78, No. 11, pp. 6618-6622, November 1981 Biochemistry Purine metabolism in the protozoan parasite Eimeria tenella (hypoxanthine-xanthine-guanine phosphoribosyltransferase/GMP-agarose affinity column/alopurinol) C. C. WANG AND P. M. SIMASHKEVICH* Merck Institute for Therapeutic Research, Rahway, New Jersey 07065 Communicated by P. Roy Vagelos, June 25, 1981 ABSTRACT Crude extracts of the oocysts ofEimeria tenella, cidia Eimenria tenella, which develops inside the caecal epithe- a protozoan parasite of the coccidium family that develops inside lial cells ofchickens, effectively takes up hypoxanthine and pref- the caecal epithelial cells ofinfected chickens, do not incorporate erentially incorporates label from it into nucleic acids when glycine or formate into purine nucleotides; this suggests lack of grown in cell culture (13, 14). Purine metabolism in this parasite capability for de novo purine synthesis by the parasite. The ex- is particularly interesting in view of the uricotelic metabolism tracts, however, contain high levels of activity of the purine sal- of chickens and the high levels of hypoxanthine known to ac- vage enzymes: hypoxanthine, guanine, xanthine, and adenine cumulate in avian tissues phosphoribosyltransferases and adenosine kinase. The absence of (15). AMP deaminase from the parasite indicates thatE. tenella cannot In this study, we have demonstrated that E. tenella cannot convert AMP to GMP; the latter thus has to be supplied by the perform de novo purine synthesis and examined the detailed hypoxanthine, xanthine, or guanine phosphoribosyltransferase of mechanism of purine salvage. A purine phosphoribosyltrans- the parasite. These three activities are associatedwith one enzyme ferase that uses hypoxanthine and guanine as well as xanthine (HXGPRTase), which has been purified to near homogeneity in as substrates (HXGPRTase) was identified in the parasite. -
Mechanism of Excessive Purine Biosynthesis in Hypoxanthine- Guanine Phosphoribosyltransferase Deficiency
Mechanism of excessive purine biosynthesis in hypoxanthine- guanine phosphoribosyltransferase deficiency Leif B. Sorensen J Clin Invest. 1970;49(5):968-978. https://doi.org/10.1172/JCI106316. Research Article Certain gouty subjects with excessive de novo purine synthesis are deficient in hypoxanthineguanine phosphoribosyltransferase (HG-PRTase [EC 2.4.2.8]). The mechanism of accelerated uric acid formation in these patients was explored by measuring the incorporation of glycine-14C into various urinary purine bases of normal and enzyme-deficient subjects during treatment with the xanthine oxidase inhibitor, allopurinol. In the presence of normal HG-PRTase activity, allopurinol reduced purine biosynthesis as demonstrated by diminished excretion of total urinary purine or by reduction of glycine-14C incorporation into hypoxanthine, xanthine, and uric acid to less than one-half of control values. A boy with the Lesch-Nyhan syndrome was resistant to this effect of allopurinol while a patient with 12.5% of normal enzyme activity had an equivocal response. Three patients with normal HG-PRTase activity had a mean molar ratio of hypoxanthine to xanthine in the urine of 0.28, whereas two subjects who were deficient in HG-PRTase had reversal of this ratio (1.01 and 1.04). The patterns of 14C-labeling observed in HG-PRTase deficiency reflected the role of hypoxanthine as precursor of xanthine. The data indicate that excessive uric acid in HG-PRTase deficiency is derived from hypoxanthine which is insufficiently reutilized and, as a consequence thereof, catabolized inordinately to uric acid. The data provide evidence for cyclic interconversion of adenine and hypoxanthine derivatives. Cleavage of inosinic acid to hypoxanthine via inosine does […] Find the latest version: https://jci.me/106316/pdf Mechanism of Excessive Purine Biosynthesis in Hypoxanthine-Guanine Phosphoribosyltransferase Deficiency LEIF B.