PROPERTIES AND MORPHOLOGY OF BARLEY EMBRYO ACETYL COA CARBOXYLASE

Acetyl CoA carboxylase was isolated and purified from barley embryos. The purified enzyme fixed CO2 at the rate of 7-7.4 .mu.mol/min per mg protein. It had a MW of 610,000 daltons and one mol of biotin per mol of enzyme. The purified enzyme aggregates during sepharose 6 B gel filtration. Aggregation of the enzyme can be prevented by using 1% sodium chloride in the elution buffer. The biotin carboxyl carrier protein of the enzyme was identified as a small polypeptide with a MW of 21,000 daltons. The peptide behaves identically to barley chloroplast biotin carboxyl carrier protein during polyacrylamide disc electrophoresis in phenol: acetic acid: urea. The morphology of purified acetyl CoA carboxylase was studied by EM using a negative staining technique. This enzyme is a globular protein with a size of 275 .+-. 8 A .times. 192 .+-. 42 .ANG. and displays characteristic cavities.