III. Mobilization of stored seed reserves after germination. 25. What happens to seed storage proteins after germination begins? 26. What is a peptidase? 27. What are the four peptidases found in seeds and how do they differ? Solution III. Mobilization of stored seed reserves after germination: When water is taken up by dry seed during germination, various metabolic processes starts leading to emergence of radicle. The major stored food reserve of the seed is mobilised to provide nutrients for growing seedling. Seedling growth is initiated with the support of metabolites formed after hydrolysis of stored reserves like proteins, oils, carbohydrates etc. 25 & 26. What happens to seed storage proteins after germination begins? And what is a peptidase? Peptidases/ proteases are enzymes which causes proteolysis (degradation) of proteins/ peptides. Dry seed contain various stored proteins like globulins, prolamins etc. During seed germination endogenous or exogenous proteases such as cysteine endopeptidases, serine carboxypeptidases and neutral aminopeptidases etc. caused protein proteolysis know as protein mobilization help in seedling growth. 27. What are the four peptidases found in seeds and how do they differ? There are various peptidases found in different seeds and these have fuction of protein degradation but site of action of every enzyme is different. Few of proteases with their active sites are mentioned bellow: 1. Carboxypeptidase (hydrolyzing carbobenzoxy-Phe-Ala at pH 5.9) 2. Amino peptidases (hydrolyzing Leu-Tyr at pH 9.2) 3. Dipeptidase (act at Ala-Gly at pH 8.5) 4. naphthylamidases (hydrolyzing Leu--naphthylamide at pH 6.4) 5. proteinases (acting on haemoglobin at pH 3.7 and on casein at pH 5.4 and 7.0) 6. Cysteine endopeptidases.