Depression of the synthesis of the intermediate and large forms of ribulose-1,5-bisphosphate carboxylase/oxygenase inRhodopseudomonas capsulata

✍ Scribed by Jessup M. Shively; Edgar Davidson; Barry L. Marrs

• Publisher: Springer
• Year: 1984
• Tongue: English
• Weight: 541 KB
• Volume: 138
• Category: Article
• ISSN: 0302-8933
• DOI: 10.1007/bf00402127

✦ Synopsis

Rhodopseudomonas capsulata produces both an intermediate (I) and a large (L) form of ribulose-l,5-bisphosphate carboxylase/oxygenase. Both forms are derepressed under CO2-1imiting conditions. The L-form of the enzyme is completely repressed when the culture is grown either photoautotrophically or photoheterotrophically with malate as the electron donor. The L-form is derepressed in the late logarithmic phase of growth when cells are grown photoheterotrophically with butyrate as the electron donor and the NaHCO3 supplement is 0.01%. The level of the I-form is increased about fivefold under latter growth conditions when compared to malate-grown cells. Analytical ultracentrifugation revealed the molecular masses of the Iand L-forms to be 300,000 and 542,000, respectively. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis showed the I-form to be composed of only one type subunit with a molecular weight of 64,000. The L-form possessed both large and small subunits with molecular weights of 58,000 and I0,000.