Effect of the embryonic axis and seed coat on protein degradation in Lens culinaris cotyledons

Abstract

Changes in protein content and protease activity (endo and exoprotease activities) in cotyledons of Lens culinaris cv Castellana were followed over eight days of seedling growth. In intact seeds, protein content decreased progressively through the study period but excision of the embryonic axis reduced this decrease. Caseinase, carboxypeptidase against benzoyl- dl-arginine- p-nitroanilide (BAPA) and carbobenzoxy- l-phenylalanyl- l-alanine (NCBZ-phe-ala), and aminopeptidase against l-leucyl- a-napthylamide (LNA) activities were present in ungerminated seeds and increased during germination of intact seeds, except for aminopeptidase activity, which decreased. Excision of the embryonic axis did not affect the development of caseinase assayed by hydrolysis into aminoacids, carboxypeptidase against BAPA and aminopeptidase against LNA, and decreased carboxypeptidase against NCBZ-phe-ala and caseinase measured by hydroylisis into peptides. The role of the seed coat on protein metabolism does not seem to be relevant, since their removal did not affect protein degradation, slightly increased caseinolytic activity assayed by hydrolysis into aminoacids, and decreased caseinase measured by peptide release.