Cysteine and methionine content of the Escherichia coli ribonucleic acid polymerase subunits.

AUTOR(ES)

Burgess, R R

RESUMO

We describe a procedure that allows cysteine and methionine content to be determined on microgram amounts of partially purified protein. The only requirements are that the protein can be obtained as a pure band after electrophoresis on a polyacrylamide gel and that some data on amino acid content be available. This method involves double labeling by growing bacterial cells with [3H]leucine and [35S]SO4 and determining the ratio of these radioisotopes incorporated into the ribonucleic acid polymerase subunits. The relative specific activities of [3H]leucine and [35S]cysteine and methionine are determined from the ratio of these isotopes incorporated into beta-galactosidase, the leucine, cysteine, and methionine contents of which are known. We have used this procedure to determine the sulfur content of the subunits of Escherichia coli ribonucleic acid polymerase. These new data are necessary to quantitate the rates of synthesis of these subunits by in vivo labeling with [35S]SO4.

Documentos Relacionados

• Wild-type and mutant in vitro products of an operon for ribonucleic acid polymerase subunits.
• Methionine and the Regulation of Ribonucleic Acid Synthesis in Escherichia coli
• β-β′ Subunits of Ribonucleic Acid Polymerase in Episome-Free Minicells of Escherichia coli
• Proofreading by DNA polymerase III of Escherichia coli depends on cooperative interaction of the polymerase and exonuclease subunits.
• Cluster of genes in Escherichia coli for ribosomal proteins, ribosomal RNA, and RNA polymerase subunits.