Activation of ribulose 1,5-bisphosphate carboxylase from Rhodopseudomonas sphaeroides: probable role of the small subunit.
AUTOR(ES)
Gibson, J L
RESUMO
The activation properties of the form I and form II ribulose 1,5-bisphosphate carboxylases from Rhodopseudomonas sphaeroides were examined. Both enzymes have a requirement of Mg2+ for optimal activity. Mn2+, Ni2+, and Co2+ can also support activity of the form I enzyme, whereas only Mn2+ can substitute for Mg2+ with the form II enzyme. The effect of different preincubations on the carboxylase reaction was also examined. Both enzymes exhibited a lag when preincubated with other than Mg2+ and CO2 before assay, but the lag was much more pronounced and the rate of the reaction was slower with the form I enzyme under these conditions. Activation of the form I carboxylase By Mg2+ and CO2 occurred more rapidly than that of the form II enzyme. The results obtained with the two distinct forms of carboxylase from R. sphaeroides, as well as studies with the spinach and Rhodospirillum rubrum enzymes, thus indicate that the presence of the small subunit affects the rate of activation by Mg2+ and CO2 as well as the rate of reactivation of ribulose bisphosphate-inactivated enzyme.
ACESSO AO ARTIGO
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=216748Documentos Relacionados
- Characterization of antiserum directed against form II ribulose 1,5-bisphosphate carboxylase from Rhodopseudomonas sphaeroides.
- Structural differences in the catalytic subunits of form I and form II ribulose 1,5-bisphosphate carboxylase/oxygenase from Rhodopseudomonas sphaeroides.
- Ribulose 1,5-bisphosphate carboxylase/oxygenase from Pseudomonas oxalacticus.
- Ribulose 1,5-Bisphosphate and Activation of the Carboxylase in the Chloroplast 1
- Presence of two subunit types in ribulose 1,5-bisphosphate carboxylase from Thiobacillus intermedius.