We found a match
Your institution may have access to this item. Find your institution then sign in to continue.
- Title
Carbamoyl Phosphate Synthetase of the Cyanobacterium Anabaena cylindrica.
- Authors
Kasahara, Masahiro; Obmori, Masayuki
- Abstract
Carbamoyl phosphate synthetase from the cyanobacterium Anabaena cylindrica was purified by the following procedures: ammonium sulfate fractionation, DEAE-Toyo-pearl, Affi-gel Blue, Sephacryl S-300 HR, and Mono Q column chromatography. The molecular weight of the holoenzyme was estimated to be 166,000 by gel permeation chromatography. SDS-PAGE showed that the enzyme consisted of two subunits with molecular weights of 130,000 and 43,000.Optimal pH of this enzyme was 7.8 in HEPES buffer. Its MgATP saturation curve was sigmoidal, yielding a Hill coefficient of 1.9 and an apparent Km of 4.5 mM. The Km values for glutamine, NH4C1 and NaHC03 were 55 μM, 182 mM and 2.5 mM, respectively. A high concentration of K+ (100 mM) was required for maximum activity. The enzyme was activated by ornithine, IMP, GMP, and GDP, and inhibited by UMP and UDP. Ornithine increased the affinity of the enzyme to ATP by acting as a positive allosteric effector, whereas UMP reduced it by acting as a negative allosteric effector.
- Subjects
CARBAMOYL phosphate synthase; CYANOBACTERIA; ANABAENA; PLANT enzymes; AMMONIUM sulfate; GEL permeation chromatography; GLUTAMINE
- Publication
Plant & Cell Physiology, 1997, Vol 38, Issue 6, p734
- ISSN
0032-0781
- Publication type
Article
- DOI
10.1093/oxfordjournals.pcp.a029227