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W Firshein

Publications and source records attributed to W Firshein.

49 records · Page 3Linked to original sources
PubMed1970

DNA-membrane complex: macromolecular content and stimulation of enzymatic activity by polyadenylic acid.

A DNA-cell membrane complex has been isolated from cell suspensions of virulent pneumococci by sarcosyl lysis followed by centrifugation on a sucrose gradient. When polyadenylic acid plus the eight naturally occurring deoxyribonucleosides and deoxyribonucleotides are added to cell suspensions, the percentage of total DNA in the complex increases with incubation time. This increase is not observed in unsupplemented cell suspensions. However, the percentages of RNA, protein, and phospholipid do not increase with incubation time in either supplemented or control complexes. A variety of deoxyribonucleotide kinases and the DNA polymerase are also detected in the DNA-membrane complex, and their specific activities are greater in complexes extracted from supplemented cell suspensions than in those extracted from controls.

Adenine Nucleotides↗
PubMed1969

Characterization of excess deoxyribonucleic acid synthesized by pneumococci in the presence of polyadenylic acid and deoxyribonucleic acid precursors.

Excess deoxyribonucleic acid (DNA) synthesized by cell suspensions of encapsulated pneumococci in the presence of polyadenylic acid plus all eight of the naturally occurring deoxyribonucleosides and deoxyribonucleotides has been characterized in several ways. The DNA represents complete molecules, is synthesized by a relatively large population at a steady rate, and is replicated in a semiconservative manner.

Adenine Nucleotides↗
PubMed1966

Differential effects of deoxyribonucleotides on respiration of virulent pneumococci.

Firshein, William (Wesleyan University, Middletown, Conn.), Robert J. Erickson, and Bernadette A. Gargan. Differential effects of deoxyribonucleotides on respiration of virulent pneumococci. J. Bacteriol. 92:1645-1654. 1966.-Four naturally occurring deoxyribonucleotides affect respiration in three virulent pneumococcal types (Diplococcus pneumoniae) differentially. Deoxyadenylic acid (dAMP) stimulates respiration in type I and slightly stimulates respiration in type III, but has no effect in type II. Deoxyguanylic acid (dGMP) stimulates respiration in type I, inhibits respiration in type II, and has no effect in type III. Thymidylic acid (dTMP) inhibits respiration of type I, but is stimulatory in types II and III. Deoxycytidylic acid (dCMP) inhibits respiration of all three pneumococcal types. Of a large number of related compounds, including many of the naturally occurring deoxynucleosides, nucleosides, nucleotides, purines, and pyrimidines, thymidine is slightly effective in types II and III, and deoxycytidine is slightly inhibitory in all three types. None of the remaining compounds affects respiration significantly. With a few exceptions, there is a correlation between the extent of uptake of each deoxynucleotide in the three types and their ability to stimulate (or inhibit) respiration. The greater the uptake, the greater the enhancement of respiration. The less uptake, the greater the inhibition of respiration. In cell-free extracts of type I, dAMP also stimulates the oxidative decarboxylation of pyruvic acid. During this reaction, dAMP is phosphorylated to deoxyadenosine diphosphate (dADP) and to deoxyadenosine triphosphate (dATP).

Carbon Isotopes↗