Substrate specificity of citrate lyase deacetylase of Rhodopseudomonas gelatinosa and Rhodopseudomonas palustris.

Citrate lyase (EC 4.1.3.6) isolated from Rhodopseudomonas palustris was investigated with regard to its kinetic properties and its subunit composition. This enzyme was inactivated by citrate lyase deacetylase (EC 3.1.2.-) of Rhodopseudomonas gelatinosa. A corresponding cross-reaction was measured with partially purified deacetylase of R. palustris and citrate lyase of R. gelatinosa. The three different subunit types (alpha, beta, and gamma) of citrate lyase from R. gelatinosa wee purified to homogeneity, and antibodies were prepared against each of the three subunits and against the native enzyme complex. In corresondence with the enzymatic interactions, immunological cross-reactions were found between anti-enzyme and anti-large subunit antibodies and citrate lyase from R. palustris. On the other hand, no immunological cross-reactions were detectable among each of the antibodies and citrate lyases from Enterobacter aerogenes, Streptococcus diacetilactis, and Clostridium sphenoides. Antibodies against the large subunit of citrate lyase inhibited the deacetylase, but antibodies against the middle and small subunits did not, indicating that the large subunits of citrate lyase are involved in binding the deacetylase.