Chemical approaches to the study of template biosynthesis: general problems and the study of transcription

Abstract

The light emitted when pion irradiated glucose is dissolved in luminol solution has been found to be proportional to the pion beam depth dose distribution in water as determined by a TE ionisation chamber. The lyoluminescence of glucose overlaps very closely with the response profile of the ionisation chamber to the 170 MeV/c Ir--mesons giving a Bragg peak to plateau ratio of 3 : 1. In comparison, the thermoluminescence response of LiF (TLD-700) to pions has been found to deviate significantly from this ratio. The close tissue equivalence of glucose, non-toxicity and its excellent lyoluminescent retention properties are important advantages over currently used dosemeters in clinical pion therapy, especially when direct in v i m measurements are considered.Pion doses ranging between 0.5 Gy (50 rad) and 30 Gy (3000 rad) were measured with an accuracy *s0/o and reproducibility 3-5%.

Chemical approaches to the elucidation of template biosynthesis: study of replication and reverse transcription

“…These residues are usually referred to as `catalytically competent'. 1,73 For the first time, this principle was applied to DNA polymerase I. 74 Oligothymidylate analogues with an alkylating group linked to the 5 H -terminal phosphate were used as affinity reagents (Fig.…”

“…Some general problems concerning the application of chemical approaches to the study of the mechanism of template biosynthesis of nucleic acids and the main results obtained in the study of enzymes that catalyse RNA biosynthesis (transcription) by chemical methods have been reviewed. 1 The present review is devoted to the application of chemical methods to the study of DNA biosynthesis, namely, its replication and reverse transcription. 2 The main chemical event in this process, viz., the elongation of the polynucleotide chain, in the case of DNA polymerases is fully identical with that for RNA polymerases considered previously.…”

“…2 The main chemical event in this process, viz., the elongation of the polynucleotide chain, in the case of DNA polymerases is fully identical with that for RNA polymerases considered previously. 1 A nucleoside triphosphate (pppN i ) complementary to the translatable element pN i of the template (its role is played by singlestranded DNA) phosphorylates the 3 H -OH group of the 3 H -terminal nucleotide residue of the growing DNA chain. It is in this way that the nucleotide residue is transferred from the triphosphate to the 3 H -OH group of the growing polymeric chain; therefore the enzyme represents a nucleotidyl transferase.…”

“…In this context, the range of problems that can be solved by chemical methods in respect of DNA polymerases differs from that for RNA polymerases described in the review cited. 1 It is also noteworthy that X-ray data about the spatial structure of DNA polymerases and their complexes with templates and substrates are now more abundant. Therefore, it is expedient to consider the large body of experimental results concerning the chemical (including affinity-based) modification of DNA polymerases in relation to the X-ray data available.…”

A Binary System of Photoreagents for High-Efficiency Labeling of DNA Polymerases

“…The method of photoaffinity labeling is widely used to study the structure and function of DNA polymerases (1)(2)(3). Arylazido derivatives of nucleic acids have been used for photoaffinity labeling of DNA polymerases and other proteins operating in the DNA replication (4).…”