Purification and characterization of acetyl-CoA carboxylase from the Diatom Cyclotella cryptica
- Solar Energy Research Institute, Golden, CO (USA)
Acetyl-CoA carboxylase from the diatom Cyclotella cryptica has been purified to near homogeneity by the use of ammonium sulfate fractionation, gel filtration chromatography, and affinity chromatography with monomeric avidin-agarose. The specific activity of the final preparation was as high as 14.6 micromoles malonyl-CoA formed per milligram protein per minute, indicating a 600-fold purification. Native acetyl-CoA carboxylase has a molecular weight of approximately 740 kilodaltons and appears to be composed of four identical biotin-containing subunits. The enzyme has maximal activity at pH 8.2, but enzyme stability is greater at pH 6.5 K{sub m} values for MgATP, acetyl-CoA, and HCO{sub 3} were determined to be 65, 233, and 750 micromolar, respectively. The purified enzyme is strongly inhibited by palmitoyl-CoA, and is inhibited to a lesser extent by malonyl-CoA, ADP, and phosphate. Pyruvate stimulates enzymatic activity to a slight extent. Acetyl-CoA carboxylase from Cyclotella cryptica is not inhibited by cyclohexanedione or aryloxphenoxypropionic acid herbicides as strongly as monocot acetyl-CoA carboxylases; 50% and 0% inhibition was observed in the presence of 23 micromolar clethodim and 100 micromolar haloxyfop, respectively.
- OSTI ID:
- 7192093
- Journal Information:
- Plant Physiology; (USA), Journal Name: Plant Physiology; (USA) Vol. 92:1; ISSN 0032-0889; ISSN PLPHA
- Country of Publication:
- United States
- Language:
- English
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