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Biomedical subjects

R Lohrmann

Publications and source records attributed to R Lohrmann.

At least 37 records · Page 2Linked to original sources
PubMed1976

Formation of nucleoside 5'-polyphosphates under potentially prebiological conditions.

Aqueous solutions of linear inorganic polyphosphates incubated in presence of Mg ions depolymerize to give trimetaphosphate. The presence of a nucleoside 5'-phosphate has little influence upon the reaction. Drying the products obtained by incubating a linear polyphosphate with Mg ions in the presence of a nucleoside 5'-phosphate yields nucleoside 5'-polyphosphates. The prebiological relevance of the reactions is discussed.

Chemical Phenomena↗
PubMed1976

Polymerization of nucleotide analogues I: reaction of nucleoside 5'-phosphorimidazolides with 2'-amino-2'-deoxyuridine.

2'-Amino-2'-deoxyuridine reacts efficiently with nucleoside 5'-phosphorimidazolides in aqueous solution. The dinucleoside monophosphate analogues were obtained in yields exceeding 80% under conditions in which little reaction occurs with the natural nucleosides. In a similar way, the 5'-phosphorimidazolide of 2'-amino-2'-deoxyuridine undergoes self-condensation in aqueous solution to give a complex mixture of oligomers. The phosphoramidate bond in the dinucleoside monophosphate analogues is stable for several days at room temperature and pH 7. The mechanisms of their hydrolysis under acidic and alkaline conditions are described.

Deoxyuridine↗
PubMed1975

Formation of nucleoside 5'-polyphosphates from nucleotides and trimetaphosphate.

When solutions of nucleoside 5'-phosphates and trimetaphosphate are dried out at room temperature, nucleoside 5'-polyphosphates are formed. The Mg++ ion shows a superior catalytic function in this reaction when compared with other divalent metal ions. Starting with nucleoside 5'-phosphates, Mg++ and trimetaphosphate, the predominant products in the nucleoside 5'-polyphosphate series pnN are p4N, P7N and p10N. Nucleoside 5'-diphosphates yield p5N and p8N, nucleoside 5'-triphosphates give p6N and p9N. The prebiological relevance of these reactions is discussed.

Adenine Nucleotides↗
PubMed1975

Prebiotic peptide-formation in the solid state. II. Reaction of glycine with adenosine 5'-triphosphate and P1,P2-diadenosine-pyrophosphate.

When a solution containing gly-N-pa and imidazole is evaporated to dryness and then maintained at a temperature between 65 degrees C and 100 degrees C, high yields of AppA and obligoglycines are obtained. We believe that ImpA is formed first, and then activates the carboxyl group of glycine or gly-A-pA. If glycine, ATP or AppA, and imidazole are heated together in the solid state, ImpA is formed and ATP , or indirectly from imidazole and gly-N-pA. Next the carboxyl group or glycine is activated by the ImpA formed in situ. The subsequent reactions of activated glycine leads to the formation of oligoglycines and the 2' (3')-glycylester of pA. Under plausible prebiobic conditions, good yields of oligoglycines up to the octamer can be obtained from glycine, ATP and imidazole.

Adenosine Diphosphate↗
PubMed1975

Triple helices formed by polyuridylic acid with some adenosine derivatives.

We have prepared a variety of derivatives of adenosine which, at neutral pH's, carry protonated amine functions. These derivatives form stable helical structures with polyuridylic acid, but the melting points are not substantially higher than those of helical complexes formed by adenosine derivatives lacking cationic groups.

Adenosine↗
PubMed1975

Prebiotic peptide-formation in the solid state. I. Reactions of benzoate ion and glycine with adenosine 5'-phosphorimidazolide.

The reactions of benzoate ion and of glycine with adenosine 5-phosphorimidazolide have been investigated. Benzoate reacts first to give the anhydride, benzoyl-adenylate, which, in the presence of excess imidazole, reacts further to give the 2'- and 3'-esters of adenosine 5'-phosphate. Glycine also first attacks the imidazolide to give an anhydride, but this compound may react further either to give 2- and 3'-esters or to form peptides, depending on the reaction conditions.

Adenine Nucleotides↗
PubMed1971

Urea-inorganic phosphate mixtures as prebiotic phosphorylating agents.

Previous attempts to phosphorylate nucleosides by heating with inorganic phosphate succeeeded only when acid phosphates such as Ca(HPO(4))(2) were used. The addition of urea and ammonium chloride to the reaction mixture permits phosphorylation in high yield with neutral or basic phosphates at temperatures in the range of 65 degrees to 100 degrees C. Since the abundant mineral, hydroxylapatite, is a satisfactory substrate for this reaction, we believe that this procedure plausible model for prebiotic phosphorylation.

Alkaline Phosphatase↗