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 [EC 2.4.2.18] from S. marcescens was purified to apparent homogeneity. The purification procedure included (NH4)2SO4 precipitation, DEAE-cellulose chromatography, Sephadex gel filtration and hydroxyapatite chromatography. The MW of the native protein as determined on a calibrated Sephadex G-200 column was 45,000. Dodecylsulfate-polyacrylamide gel electrophoresis in the presence of reducing agent revealed a subunit MW of 43,000 .+-. 900, suggesting that the enzyme exists as a monomer. The sequence of the amino-terminal 38 residues revealed that 3 amino acids, glutamine (6 residues), glutamic acid (5 residues) and serine (5 residues) comprised 42% of the sequence composition.