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ABSTRACT: The finding of the enhanced polymerization of N,N-carbonyldiimidazole (CDI) activated l-α-glutamic acid (Glu) by alkali cations like Na+ and K+ and CDI-activated l-α-arginine (Arg) by halide anions like Cl- and other common ions indicates the importance of the weak electrostatic coordination of these common ions on the polymerization of charged amino acids in H2O. Here the copolymerization of l-arginine-N-carboxyanhydride (l-Arg-NCA) mixed with l-glutamic acid-N-carboxyanhydride (l-Glu-NCA) produced much longer peptides than that of the same concentration of l-Arg-NCA or l-Glu-NCA, and the optimal proportion of l-Glu-NCA over l-Arg-NCA for the longest peptide formation was 1:1. NaCl affected the sequences of the peptides formed in the mixed l-Arg-NCA with l-Glu-NCA, yielding peptides with significantly more Arg residues than Glu residues. Enzymatic hydrolysis of the formed peptides uncovered significantly more two residues of the same charges. These data strengthen the importance of weak electrostatic interactions in the polymerization of charged amino acids in H2O.
02/2008;
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ABSTRACT: Abstract— In the tentative simulation of prebiotic synthesis, it was found that the photolysis yield of nucleic acid bases, nucleosides and nucleotides (NA) undergoing UV irradiation was sharply enhanced by added orthophosphate. Filter experiments demonstrated that the enhancement is due to UV quanta of wavelength less than 215 nm in the emission spectrum of a medium pressure mercury lamp. The phosphate-induced enhancement of the photolysis of NA constitutes an additional channel of nucleic acid monomer degradation through their interaction with photoionized phosphate radicals.
Photochemistry and Photobiology 01/2008; 65(4):656 - 659. · 2.41 Impact Factor
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ABSTRACT: NaCl significantly enhanced the longer oligoarginine formation in the oligomerization of L-arginine activated by N,N'-carbonyldiimidazole (CDI) in homogeneous aqueous solution. The optimal concentration of NaCl for the highest yield of longer oligoarginine formation is around 1M. It is suggested that the weak interactions of Cl(-) with the positive-charged guanidinium group of the oligoarginines formed in the oligomerization of L-arginine are responsible for the enhancement by NaCl.
Biopolymers 02/2006; 81(1):1-7. · 2.87 Impact Factor
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ABSTRACT: The presence of NaCl was found to significantly enhance the formation of longer peptides in N,N'-carbonyldiimidazole induced oligomerization of L-glutamic acid in homogeneous aqueous solution. The enhancement was detected in the presence of as low as 0.01-M NaCl and the highest yield of longer oligomers was achieved in the presence of 1-M NaCl. The possible prebiotic relevance is discussed.
Origins of Life and Evolution of Biospheres 09/2005; 35(4):313-22. · 2.66 Impact Factor
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ABSTRACT: The presence of NaCl was found to significantly enhance the formation of longer peptides in N,N′-carbonyldiimidazole induced oligomerization of l-glutamic acid in homogeneous aqueous solution. The enhancement was detected in the presence of as low as 0.01-M NaCl and
the highest yield of longer oligomers was achieved in the presence of 1-M NaCl. The possible prebiotic relevance is discussed
Origins of Life and Evolution of Biospheres 07/2005; 35(4):313-322. · 2.66 Impact Factor
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ABSTRACT: Adenosine-5'-methylphosphate (MepA) initiates the oligomerization of the 5'-phosphorimidazolide of uridine (ImpU) in the presence of montmorillonite clay. Longer oligomers form because the 5'-phosphate is blocked with a methyl group that prevents the formation of cyclic- and pyrophosphate-containing compounds. The MepA initiates 69-84% of the 5-9 charge oligomers, respectively. The montmorillonite catalyst also provides selectivity in the oligomerization reactions so that the main reaction pathway is MepA --> MepA3'pU --> MepA3'pU2'pU --> MepA3'pU2'pU3'pU. MepA did not enhance the oligomerization of ImpA. The relative rates of the reactions were determined from an investigation of the products in competitive reactions. Selectivity was observed in the reaction of ImpU with equimolar amounts of MepA3'pU and MepA2'pU where the relative reaction rates are 10.3:1, respectively. In the reaction of ImpA with MepA3'pA and MepA2'pA the ImpA reacts 5.2 times faster with MepA3'pA. In the competitive reaction of ImpU and ImpA with MepA3'pA and MepA3'pU the elongation proceeds on MepA3'pA 5.6 times more rapidly than with MepA3'pU. There is no correlation between the extent of binding to the montmorillonite and reaction rates in the formation of longer oligomers. The formation of more than two sequential 2',5'-linkages in the oligomer chain proceeds more slowly than the addition to a single 2',5'-link or a 3',5'-link and either chain termination or elongation by a 3',5'-linage occurs. The central role that catalysis may have had in the prebiotic formation of biopolymers is discussed.
Origins of Life and Evolution of Biospheres 07/2005; 35(3):187-212. · 2.66 Impact Factor
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Analytical Biochemistry 10/2004; 332(1):199-201. · 3.00 Impact Factor
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ABSTRACT: It is proposed that catalysis by minerals and metal ions had a central role in the steps that led to the origins of life. In particular, the formation of biopolymers in the presence of water requires catalysis to compete with hydrolytic reactions. Catalysis is required to limit the no. of isomers generated so that the longer polymers necessary for the origins of life are formed. Montmorillonite clay catalyzes the formation of 6-14 mers from activated monomers of A, G, U and C in aq. soln. Daily addn. of activated A monomers to a 10 mer primer results in the formation of 40-50 mers of adenylic acid and 30 mers of uridylic acid. The sequence selectivity and regioselectivity in phosphodiester bond formation result from the montmorillonite catalysis. Reaction of D, L-activated monomers of A and U lead to the preferential formation of homochiral dimers. [on SciFinder (R)]
