Purification, subunit structure and partial amino-acid sequence of anthranilate-5-phosphoribosylpyrophosphate phosphoribosyltransferase from the enteric bacterium Serratia marcescens.

Abstract

The enzyme anthranilate-5-phosphoribosylpyrophosphate phosphoribosyltransferase from Serratia marcescens was purified to apparent homogeneity. The purification procedure included ammonium sulfate precipitation, DEAE-cellulose chromatography, Sephadex gel filtration and hydroxyapatite chromatography. The molecular weight of the native protein as determined on a calibrated Sephadex G-200 column was 45000. Dodecylsulfate-polyacrylamide gel electrophoresis in the presence of reducing agent revealed a subunit molecular weight of 43000 +/- 900, suggesting that the enzyme exists as a monomer. The sequence of the amino-terminal 38 residues revealed that three amino amino acids, glutamine (six residues), glutamic acid (five residues) and serine (five residues) comprised 42% of the sequence composition.