Interpretation of Sucrose Gradient Sedimentation Pattern of Deoxyribonucleic Acid Fragments Resulting from Random Breaks

Interpretation of sucrose gradient sedimentation pattern of deoxyribonucleic acid fragments resulting from random breaks.

Mass distribution in a sucrose gradient of deoxyribonucleic acid (DNA) fragments arising as a result of random breaks is predicted by analytical means from which computer evaluations are plotted. The analytical results are compared with the results of verifying experiments: (i) a Monte Carlo computer experiment in which simulated molecules of DNA were individuals of unit length subjected to ran...

Alkaline sucrose gradient sedimentation of chromosomal deoxyribonucleic acid from Escherichia coli PolA + and PolA - strains during thymine starvation.

Single-strand breaks were not detected in the deoxyribonucleic acid of Escherichia coli after thymine starvation for up to 180 min, even in a sensitive PolA(-) strain.

The sedimentation characteristics of deoxyribonucleic acid from human tissues.

1. Evidence is presented for the presence of pyridoxamine phosphate oxidase and a pyridoxal phosphate phosphatase in aqueous extracts of E8cherichia coli. 2. Spectrophotometric methods have been developed for the precise measurement of substrate and product concentrations in both enzyme systems. Specific activities of the order of 10-2 tumole/30 min./mg. ofprotein/ml. ofreaction mixture are rep...

Sucrose gradient centrifugation sedimentation standards: a simplified technique.

Strand displacement during deoxyribonucleic acid synthesis at single strand breaks.

Synthesis of DNA by DNA polymerases has been studied by using circular duplex DNA templates which contain single phosphodiester bond interruptions (nicks). Escherichia coli DNA polymerase can initiate synthesis at nicks by the covalent attachment of nucleotides to the 3’ end of the primer strand. An initial phase of synthesis is accompanied by the removal of nucleotides from the 5’ end of the n...