Tryptic hydrolysis of paramyosin from invertebrates: Rate and extent of proteolysis

Abstract

The rate extent of the action of trypsin (EC 3.4.4.4) on Pinna nobilis and Pecten maximum paramyosin were followed by different methods, namely total nitrogen, α-amino nitrogen and arginine content in the trichloroacetic acid-soluble fraction, alkali uptake and N-terminal residues in the digest mixture. The results obtained permi one to say that the number of bonds split typrsin in both cases is approximately half of the susceptible bonds present in the whole molecule. About 80% of the total arginine liberated by the enzyme is free or in an N-terminal position. The kinetics of proteolysis were studied by two different methods and they clearly indicate the existence of at least two and possibly three simulataneous reactions proceedings at different rates. The rate contants suggest that one class of peptide bonds is much more susceptible to attack than others. The results are discussed in the light of the proposed secondary and tertiary structure of paramyosin.