Studies on cinnamic acid-4-hydroxylase from wounded potato tissue: isolation and characterization of cinnamic...

Cinnamic acid-4-hydroxylase activation factor has been found to be located in the supernatant fraction of wounded potato tissue homogenate in phosphate buffer. The factor has been purified to homogeneity as judged by SDS polyacrylamide gel electrophoresis, by heat treatment on boiling water-bath for 7.5 min followed by dialysis with cut off limit of 8 kDa and final separation by gel filtration on Sephadex G-50 column. Gel filtration resolved this into three active fractions of molecular mass 12500, 10000 and 8500 Da conjugated to a fluorescent compound and subsequently identified as a folate derivative. The amino acid analysis of polypeptide chains of these fractions revealed that the polypeptides were rich in glutamic and aspartic acids. The fluorescent moiety of the complex released from polypeptide chain of molecular weight 10000 by mild acid hydrolysis was able to support the growth of Lactobacillus casei ATCC 7469 which requires folic acid for its growth. On storage, this compound degraded into a number of fluorescent products identified as p-amino benzoic acid, p-amino benzoyl glutamic acid, pteroic acid and 6-methyl pterin indicating that the activation factor is a folic acid derivative conjugated with the polypeptide chain.