Fat Metabolism in Higher Plants: XXXI. PURIFICATION AND PROPERTIES OF PLANT AND BACTERIAL ACYL CARRIER PROTEINS

Abstract

The acyl carrier proteins from Escherichia coli, Arthrobacter viscosus, avocado mesocarp (Persea americana), and spinach (Spinacea oleracea) have been purified to homogeneity and their chemical compositions have been examined. They are heat-stable and contain an abundance of acidic amino acids. Their total amino acid compositions are remarkably similar. The enzymic function of each acyl carrier protein was examined with fatty acid synthetase enzymes from both E. coli and spinach chloroplasts. These experiments showed that bacterial acyl carrier proteins had higher specific activities than the plant acyl carrier proteins in both synthetase systems. It was observed that the bacterial acyl carrier proteins from both E. coli and Arthrobacter were functionally indistinguishable. The spinach and avocado acyl carrier proteins were also similar to each other in their reactions with the synthetases. The fatty acids produced in cross-reactions with the use of plant acyl carrier proteins with the E. coli synthetase differ markedly from the products obtained with the bacterial acyl carrier proteins in the E. coli system. In contrast, the employment of E. coli acyl carrier protein instead of spinach acyl carrier protein in the spinach synthetase system did not alter the products of synthesis.