Lawrence Berkeley National Laboratory Recent Work Title CHEMICAL EVOLUTION: CONDENSATION REACTIONS OF NUCLEO-TIDES AND AMENO ACIDS IN AQUEOUS SOLUTION Permalink https://escholarship.org/uc/item/4b27k0kd Author Bjornson, Loring Kent. Publication Date 1970-03-01 eScholarship.org Powered by the California Digital Library University of California UCRL- 197 33 C_ . W%_ CHEMICAL EVOLUTION: CONDENSATION REACTIONS OF NUCLEOTIDES AND AMINO ACIDS IN AQUEOUS SOLUTION RECEIVED LAWRENCE Loring Kent Bjornson RADIATION LABORATORY (Ph.D. Thesis) MAY 211970 March 1970 LIBRARY AND DOCUMENTS SECTLON AEC Contract No. W-.7405-eng-48 TWO-WEEK LOAN COPY This is a Library Circulating Copy which may be borrowed for two weeks. For a personal retention copy, call Tech. Info. DiuIsIon, Ext. 5545 I1 • C) LAWRENCE RADIATION LABORATORY UNIVERSITY of CALIFORNIA BERKELEW DISCLAIMER - This document was prepared as an account of work sponsored by the United States Government. 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The views and opinions of authors expressed herein do not necessarily state or reflect those of the United States Government or any agency thereof or the Regents of the University of California. -111 - TABLE OF CONTENTS Page 4 ABSTRACT -vi- I. HISTORY OF CHEMICAL EVOLUTION STUDIES 1 A. General Considerations 2 B. Abiogenic Synthesis of Biomonomers 7 Amino Acids 8 Heterocyclic Bases of Nucleic Acids 10 Nucleosides and Sugars 11 Nucleotides 12 Fats 12 Porphyrins 13 C. Abiogenetic Synthesis of the Biopolymers 14 Polypeptides 15 Polynucleotides 19 D. Interactions and Organization of l3iopolymers 20 Formation of Membrane Structures 21 Self-replicating Systems and the Genetic Code 24 II. REACTIONS OF NUCLEOTIDES WITH VARIOUS CONDENSING AGENTS 36 Reactions of UMP-2' ,3 39 Reaction of AMP-5' with Ethanol 42 Reactions of AMP-5' with Water-soluble Carbodiimides 48 Reactions of AMP-5' in the Presence of Polypeptides 59 Summary 66a -iv- TABLE OF CONTENTS (continued) Page F. Experimental Section 67 1. Standard Procedures for 14 C-labeled Compounds 67 2. Synthesis of Cyanoacetylene 69 3. Synthesis of A5 ppA 70 4. Synthesis of EPCMeI 71 + 5. Synthesis of Poly-L-lysine-c-N(CH 3 ) 3 72 6. Reactions of 8- 14 C-AMP-5' with Carbodiimides 72 7. Synthesis of 1,3-bis-(2-methoxyethyl) Carbodiimide 73 8. Solvent Systems and Buffers 75 III. REACTIONS OF AMINO ACIDS WITH VARIOUS CONDENSING AGENTS 76 A. Introduction 76 B. Condensation Reactions of Glycine 83 Reaction with Cyanamide Derivatives 83 Reaction with Carbodiimides 88 C. Reactions of Pheny1a1anine with Carbodiimides in the Presence of Polypeptides and Polynucleotides 94 D. Reactions of Lysine with Carbodiimides 98 1. Reactions of Lysine in the Presence of Polynucleotides 105 E. Summary 110 F. Experimental Section 112 Synthesis of 14 C-1,3-bis-(2-methoxyethyl) Carbodiimide 112 Preparation of Lysine: Polyadenylic Acid Complex 113 Reaction of 3H-Lys and 2,4-Dinitrofluorobenzene 114 - v- TABLE OF CONTENTS (continued) Page Liquid Scintillation Counting of Tritium and Carbon-14 Simultaneously 115 Reactions of 14C-Amino Acids 115 ACKNOWLEDGMENTS 117 REFERENCES 118 -vi-- CHEMIAL EVOLUTION: CONDENSATION REACTIONS OF NUCLEOTIDES - AND AMINO ACIES IN AQUEOUS SOLUTIONS Loring Kent Bjornson Laboratory of Chemical Biodynamics Lawrence Radiation Laboratory University of California V Berkeley March 1970 ABSTRACT The condensation reactions in aqueous solution of severl nucleo- V tides and amino acids have been studied since, it is believed that this type of reaction was important in the formation of polypeptides and polynucleotides on the prebiotic Earth. V A number of condensing agents were examined to determine which were the most effective in reactions with nucleotides. The con- densing agents included four water-soluble carbodiimides, cyanamide V and two of its derivatives, and cyanoacetylene. In a model reaction of AMP-5 and ethanol it was found that only the carbodiimides gave satisfactory yields of the ethyl phosphate ester under mild condi- tions. AMP-S , reacts with the carbodiimides to form diadenosine pyrophosphate, A 5 ppA. It was found that l-ethyl-3-(3-dimethylamino- propyl) carbodiimide hydrochloride (EPC) produced A 5 ppA in larger yields than the other carbodiimides and a small amount of pApA was observed. Numerous attempts to demonstrate a catalytic effect for the basic polypeptides on the self-condensation of AMP-5' using the 2 One of the appealing features of the chemical evolu- tion theory is that. it presents a continuity of evolution • starting with very simple molecules and proceeding through • today's living systems. It is also a logica.l backwards extrapolation of Darwinian evolution to the point where the .first living system appeared and further'tb the point where only. the constituent chemicals of living . systems were pres- ent. It has been noted5 that..Charles Darwin had also con- • ceived.of this possibility in 1871. However, only recently • has scientific knowledge and technology.advanced to a stage where this .problem could .be investigated experimentally. A. General Considerations . In discussing chemical evolution a nuiriber of questions arise about the primordial environment, the time span, etc. The, exact answers to many of these questions are not known but a general picture has been drawn based on evidence from a variety of scientific disciplines, such as astronomy, geology, chemistry and physics. The question of the length of time available for chemical evolution has been given an approximate answer of one billion .years. This is an estimate of the time between the formation of the earth and the emergence of living systems. •- After the arrival of life, chemical evolution would rapidly decrease since the chemicals necessary for it would be used by living organisms as in today's environment. It 3 is currently accepted that the earth was formed by condensa- tion of a stellar dust cloud 4.5-4.8 x 10 9 years ago. 6 Evidence, has recently been found for the existence of simple 9 7,8 unicellular organisms at least 3.1 x 10 years ago and multicellular organisms .2-2.5 x 10 9 years ago. 9 The question of the environment of the primitive earth is very important since most experiments considered relevant.to chemical evolution are carried out under condi- tions which are presumed to be like those of the primitive earth. There isa general consensus that theearly atmos- phere contained little orno molecular oxygen. There is some question as to the exact composition of this atmosphere (see Chapter 3 of Ref. 10) with W. Rubey 11 favoring an 12 atmosphere dominated by N 2 and CO 2 and H.Urey favoring CH4 and NH 3 as the dominant species. H. Holland 13 has proposed a model containing elements of both the above theories wherein he has three different stages of development for the atmosphere. The initial stage is highly reduced and contains CH 4 , NH 3 and H2 0, the second stage has N 2 , CO2 and H2 0, and the final stage is oxidized (molecular oxygen is present). The third stage is like our present atmosphere and is thought to take place after living systems are formed, especially photosynthetic systems which evolve oxygen. Probably the most compelling evidence for the early reduced atmosphere is the fact that when energy in the form of ionizing radiation or heat is put into a mixture of the 4 reduced gases (CH 4 , NH 3 and H 2 0) many biologically important compounds are formed, but when the conditions become oxi- dizing the organic synthesis stops. 14 The sources of energy available on the primitive earth have been categorized by Miller and Urey) 5 They conclude that by far the largest source of energy was the sun. This is not surprising since life on our planet today is dependent on the sun for its energy ultimately. Other sources of • energy in their estimated order of abundance are electric discharges, radioactivity, volcanoes and cosmic rays. The CH 4 -NH 3 -H20 mixtures show little UV absorption above 2000 A and since there is considerable technical diff i- cultyin using lower wavelength light most experimental work has simulated the other types of energy sources. Life is generally assumed to have arisen in the sea. Certainly water is necessary for all forms of life both aero- bic and anaerobic, and it constitutes the major part of all organisms. Thus, in chemical evolution studies most experi- mental approaches emphasize the importance of water either directly or indirectly. For example, in the irradiation of the reduced gases water serves as a means for concentrating the products formed and protecting them from degradation. Also, the polymerization of the biomonomers in dilute aqueous solution with simple condensing agents has been studied by several investigators and shows considerable promise as a prominent event in chemical evolution. The pH, temperature and salt concentration of the primitive ocean are not known. 5 It is usually assumed that these variables are not greatly different than in the present oceans except for probably a lower salt concentration in the primitive oceans. It should be emphasized that there probably existed a great variety of microenvironments on the prmordial earth since the earth presently contains locales which differ greatly in the above- mentioned variables.