Replication of polyoma DNA in isolated nuclei. 3. The nucleotide sequence at the RNA-DNA junction of nascent strands.
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Adenosine Triphosphate↗
Biomedical subjects
V Pigiet
Publications and source records attributed to V Pigiet.
Discontinuous elongation of both strands at the replication forks in polyoma DNA replication.
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Adenosine Triphosphate↗
RNA-linked short DNA fragments during polyoma replication.
During in vitro incubation, nuclei from polyoma-infected cells elongate the daughter strands of the replicative intermediate of polyoma DNA. This process is now shown to involve the transient formation of short fragments (4-5 S), a process that is stimulated by the addition of ribonucleoside triphosphates. The presence of stretches of RNA at the 5'-end of short DNA chains was determined from Cs(2)SO(4) equilibrium centrifugation and from the finding that isotope from alpha-(32)P-labeled deoxynucleoside triphosphates was recovered in 2'(3')-ribonucleotides after alkaline hydrolysis. Transfer occurred preferentially with [alpha-(32)P]dCTP as substrate. Starvation for deoxynucleotides by in vivo treatment with hydroxyurea resulted in the accumulation of short fragments that are deficient in RNA. Our results suggest that a late step during the discontinuous synthesis of polyoma DNA is selectively inhibited when deoxynucleotides are in short supply.
Adenosine Triphosphate↗
Hybridization of native and chemically modified enzymes. 3. The catalytic subunits of aspartate transcarbamylase.
Succinylation of the catalytic subunits of ATCase yielded a relatively homogeneous, inactive electrophoretic variant which upon mixing with native regulatory subunits formed a complex the size of the native enzyme. Hybridization experiments with mixtures of this variant and the native catalytic subunits in the presence of excess regulatory subunits yielded three different molecular complexes which were separated and individually characterized. The number and properties of the various components indicated that each ATCase molecule contains two catalytic subunits. Hybridization was also effected at the intrasubunit level by dissociation and reconstitution of mixtures of the native and modified catalytic subunits. These experiments produced four components showing thereby that each catalytic subunit is composed of three polypeptide chains. The potential use of the various hybrids is discussed in relation to the unique properties manifested by regulatory enzymes.
Aspartic Acid↗