title: Partial purification and characterization of CTP:cholinephosphate cytidylyltransferase from castor bean endosperm.
abstract: CTP: cholinephosphate cytidylyltransferase (EC 2.7.7.15) has been purified approximately 600-fold from postgermination endosperm of castor bean. The enzyme was solubilized with n-octyl beta-D-glucopyranoside and then subjected to ion exchange and gel filtration chromatography. The Km's of the purified enzymatic activity were 0.37 and 1.1 mM for CTP and choline phosphate, respectively. Magnesium was required for activity. The purified cytidylyltransferase activity was inhibited by both phosphate and ATP. The extent of ATP inhibition was dependent on preincubation time, temperature, and Mg2+ and Ca2+ concentrations. The possible regulation of cytidylyltransferase in castor bean endosperm by protein phosphorylation is discussed.
authors.affiliation: Department of Botany, Louisiana State University, Baton Rouge 70803-1705.
authors.forename: X M
authors.initials: XM
authors.lastname: Wang
authors.forename: T S
authors.initials: TS
authors.lastname: Moore
mesh_terms: D000255:Adenosine Triphosphate / Q000494:pharmacology; D002367:Ricinus communis / Q000201:enzymology*; D002474:Cell-Free System; D019916:Choline-Phosphate Cytidylyltransferase; D002852:Chromatography, Ion Exchange; D007700:Kinetics; D009713:Nucleotidyltransferases / Q000037:antagonists & inhibitors / Q000302:isolation & purification* / Q000378:metabolism; D010710:Phosphates / Q000494:pharmacology; D010947:Plants, Toxic; D012278:Ricinus / Q000201:enzymology*; D012639:Seeds / Q000201:enzymology; D012995:Solubility
chemical_list: D010710:Phosphates; D000255:Adenosine Triphosphate; D009713:Nucleotidyltransferases; D019916:Choline-Phosphate Cytidylyltransferase