PMID:6408075

Citation	Andrews, TJ and Ballment, B (1983) The function of the small subunits of ribulose bisphosphate carboxylase-oxygenase. J. Biol. Chem. 258:7514-8
Abstract	When ribulose bisphosphate carboxylase-oxygenase from Synechococcus (strain RRIMP N1) was precipitated under mildly acidic conditions, most of its small subunits remained in solution. The precipitated enzyme readily redissolved at neutral pH and remained as an octamer of large subunits with some small subunits still attached. Optimum pH for this separation was 5.3 and disulfide-reducing reagents were not necessary. The fraction of small subunits removed by a single precipitation increased with increasing NaCl concentration. Catalytic activity of small subunit-depleted enzyme was linearly proportional to the fraction of small subunits remaining, while the carboxylase:oxygenase activity ratio and the affinity for CO2 remained constant. When isolated small subunits were added back to depleted enzyme preparations at neutral pH, reassociation occurred with return of catalytic activity. Under the usual assay conditions at pH 7.7, the binding constant of the small subunits was estimated to be about 10(-9) M. The small subunits also bound avidly to surfaces. However, loss of small subunits from the enzyme during the course of purification was minimal. The results are consistent with a simple model in which only those large subunits which have a small subunit bound to them are catalytically competent. Thus, an essential, even if indirect, role for the small subunits in catalysis is indicated.
Links	PubMed
Keywords	Carboxy-Lyases/metabolism; Cyanobacteria/enzymology; Hydrogen-Ion Concentration; Kinetics; Macromolecular Substances; Osmolar Concentration; Ribulose-Bisphosphate Carboxylase/isolation & purification; Ribulose-Bisphosphate Carboxylase/metabolism
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Annotations

Gene product	Qualifier	GO Term	Evidence Code	with/from	Aspect	Extension	Notes	Status
SYNP2:RBS	enables	GO:0016984: ribulose-bisphosphate carboxylase activity	ECO:0000314: direct assay evidence used in manual assertion		F		Seeded From UniProt	complete
SYNP2:RBS		GO:0016984: ribulose-bisphosphate carboxylase activity	ECO:0000314:		F		table 2 and figure 1b	complete CACAO 9787

References

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