Abstract
Phosphoenolpyruvate carboxylase (PEPC; EC 4.1.1.31) was purified to electrophoretic homogeneity from Crassula argentea leaves according to established methods incorporating DEAE, hydroxylapatite, and Mono Q chromatography. The purified enzyme had a specific activity of 20-25 units/ mg of protein. Purified PEPC was further processed by blue agarose affinity chromatography and gel filtration to help ensure the removal of potential contaminating kinases. Autoradiography revealed that phosphorylation of PEPC occurred when the purified enzyme was incubated with [γ- 32 P]ATP-Mg 2+ . Radiolabel was not incorporated when [α- 32 P]ATP-Mg 2+ was utilized as substrate. Phosphorylation of the PEPC culminated in its activation: the K i for L-malate increased 2.5-fold while the maximum inhibition dropped from 73 to 39% and the K m for magnesium phosphoenolpyruvate dropped from 69 to 53 μM. These data are consistent with phosphorylation sensitive PEPC from C. argentea possessing an auto-kinase function or, alternatively, the copurification of a kinase that possesses a high specific activity and tightly associates with PEPC.
Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
