Structural differences in the catalytic subunits of form I and form II ribulose 1,5-bisphosphate carboxylase/oxygenase from Rhodopseudomonas sphaeroides.

There are significant differences in the large subunits of form I and form II ribulose 1,5-bisphosphate carboxylase/oxygenase isolated from Rhodopseudomonas sphaeroides. Two-dimensional peptide mapping of carboxymethylated large subunits clearly indicates that there are differences in the primary structure of the two proteins. These results are supported by limited proteolysis with three different proteases and by subsequent analysis by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. These data, in conjunction with immunological studies and investigations on the regulation of the two enzymes, support the conclusion that the large subunits of form I and form II ribulose 1,5-bisphosphate carboxylase/oxygenase may be different gene products.