Occurrence and Some Properties of Two Types of δ-Aminolevulinic Acid Synthase in a Facultative Methylotroph, Protaminobacter ruber

Abstract

In addition to the α-ALA synthase already reported (Fraction I: molecular weight, 100, 000; optimal pH, ca. 8.0), an isozyme (Fraction II: molecular weight, 64, 000; optimal pH, ca. 6.4) was found in Protaminobacter ruber grown in the dark after an initial light period (20-30hr). The fraction I- and II-enzymes were separable by gel-filtration through Sepharose 6B. While the former was formed constitutively, the latter was formed inducibly under the conditions for bacteriochlorophyll formation. Therefore, the fraction II-isozyme seems to be responsible for the biosynthesis of bacteriochlorophyll.