EFFECT OF THE EMBRYONIC AXIS AND SEED COAT ON PROTEIN-DEGRADATION IN LENS-CULINARIS COTYLEDONS

Changes in protein content and protease activity (endo and exoprotease activities) in cotyledons of Lens culinaris cv Castellana were follow ed over eight days of seedling growth. In intact seeds, protein conten t decreased progressively through the study period but excision of the embryonic axis reduced this decrease. Caseinase, carboxypeptidase aga inst benzoyl-DL-arginine-p-nitroanilide (BAPA) and carbobenzoxy-L-phen ylalanyl-L-alanine (NCBZ-phe-ala), and aminopeptidase against L-leucyl -a-napthylamide (LNA) activities were present in ungerminated seeds an d increased during germination of intact seeds, except for aminopeptid ase activity, which decreased. Excision of the embryonic axis did not affect the development of caseinase assayed by hydrolysis into aminoac ids, carboxypeptidase against BAPA and aminopeptidase against LNA, and decreased carboxypeptidase against NCBZ-phe-ala and caseinase measure d by hydroylisis into peptides. The role of the seed coat on protein m etabolism does not seem to be relevant, since their removal did not af fect protein degradation, slightly increased caseinolytic activity ass ayed by hydrolysis into aminoacids, and decreased caseinase measured b y peptide release. (C) 1997 Elsevier Science B.V.