Separation of Mg-Protoporphyrin IX and Mg-Protoporphyrin IX Monomethyl Ester Synthesized de novo by Developing Cucumber Etioplasts

Abstract

High pressure liquid chromatography was used to demonstrate that chelation of Mg2+ into protoporphyrin IX precedes methylation in isolated greening etioplasts from cucumber (C. sativus L. cv. Beit Alpha) cotyledons. Mg-protoporphyrin IX synthesized in vitro from protoporphyrin IX, Mg2+ and ATP or exogenous Mg-protoporphyrin IX could serve as substrates for the methylation step. In either case, S-adenosylmethionine was the methyl donor and could not be replaced by ATP plus methionine.