Copurification of citrate lyase and citrate lyase ligase from Rhodopseudomonas gelatinosa and subsequent separation of the two enzymes.

A procedure has been worked out which allowed the purification and crystallization of a citrate lyase/citrate lyase ligase complex from Rhodopseudomonas gelatinosa. The complex was subsequently separated to yield two homogeneous enzymes. Citrate lyase ligase was purified 365-fold with a yield of 3.23%. The molecular weight of the enzyme was estimated to be 39500, the enzyme consisted of one polypeptide chain. The reaction rates for ATP, acetate and citrate lyase (sulfhydryl form) followed Michaelis-Menten kinetics (Km values: 0.14 mM, 5 mM and 37 nM respectively). Citrate lyase ligase exhibited a high substrate specificity and could not react with citrate lyases from nonphototrophic microorganisms. In contrast to the ligase from Streptococcus diacetilactis, the enzyme from R. gelatinosa was extremely labile; however, it could be stabilized by nucleotides, the most potent stabilizing one being ADP.