Metabolism of Nucleic Acids (Macromolecular DNA and RNA)

Abstract

Since it is manifestly impossible to cover the entire field of nucleic acid metabolism in one article, I have restricted this review to recent work on enzymes which have to do with macromolecular nucleic acids. Sections are included on the synthetic enzymes DNA polymerase and RNA polymerase and on enzymes which alter the nucleic acids in their macromolecular state, namely, the DNA and RNA methylases. The concluding section deals with degradative enzymes, chiefly RNase, DNase, and polynucleotide phosphoryl ase, but in a much more cursory manner. The review is based on an exten sive, but certainly not complete, coverage of the recent literature. References 1 through 10 are reviews, books, special collections of articles, and critical papers which deal with various aspects of the subject matter of this review. ENZYMES WHICH SYNTHESIZE NUCLEIC ACIDSThe DNA polymerases and RNA polymerases catalyze the synthesis of polynucleotides by the complementary copying of pre-existing polynucleo tides. The precursors are the appropriate nucleoside triphosphates, and a bivalent cation is required (11-16). During the period under review, there have appeared no serious reasons to doubt that these are the principal, and quite possibly the only, enzymes which catalyze the synthesis de novo of DNA and RNA in nature. Beyond this, a great deal remains to be eluci dated, and much of the recent work has dealt with such matters as the chem ical and physical nature of the polynucleotide templates or primers and prod ucts, details of the reaction mechanisms, differences between the reactions in vivo and in vitro, the association of the enzymes with other cell components, and so forth.DNA POLYMERASEThe location of DNA polymerase in the cell.-In bacterial extracts DNA polymerase has been observed to sediment together with DNA (e.g., 17, 18) . In higher organisms, however, a number of studies had indicated that the enzyme is actually located outside the cell nucleus. In view of the unexpected nature of these findings, the matter has been pursued in several laboratories; and reports have now appeared which provide evidence that at least some of

Prolonged fasting increases purine recycling in post-weaned northern elephant seals

“…The purines adenine and guanine are essential components of nucleic acids, high-energy phosphates and signaling molecules such as cyclic adenosine monophosphate and cyclic guanosine monophosphate (Elson, 1965;Verma and Eckstein, 1998). Dietary ingestion of purines contributes to the maintenance of the body pool whereas de novo synthesis of purines from non-purine precursors requires energy (Raivio et al, 2001).…”

Template functions in the enzymic formation of polyribonucleotides, I. Integrity of the DNA template.

“…Examples abound in the literature: e.g., the different effects of polyamines on intact and denatured DNA5 6, 26 and, most significantly, the finding that heat-denatured DNA, though usually a poorer template as judged by the rate of polymer formation, binds more An aqueous solution of DNA prep. 3 (1 mg/ml) was divided into three parts. One portion was brought rapidly to pH 2 with N HC1 and immediately returned to pH 7 with N KOH.…”

Synthesis and Characterization of Mixed Ligand Complexes of Copper(II) with Adenine and Dicarboxylic Acids

“…And again, a nucleotide is made up of three components: a nucleobase, a pentose sugar, and a phosphate group. Adenine 2 is a derivative of purine, consisting of a fused pyrimidine-imidazole ring system with conjugated double bonds and is an essential nucleobase [3][4][5] of both DNA and RNA. Since heterocyclic nitrogen of the nucleic acid bases carry lone electron pairs, they are good ligands for alkali/alkaline earth and transition metals cations 6 .…”