THE COMPLETE AMINO-ACID-SEQUENCE OF CHITINASE-A FROM THE SEEDS OF RYE(SECALE CEREAL)

The complete amino acid sequence of rye seed chitinase-a (RSC-a) has b een analyzed. RSC-a was cleaved with cyanogen bromide and the resultin g three fragments, CB1, CB2, and CB3, were separated by gel filtration . The amino acids of the IV-terminal fragment CB1 were sequenced by an alyzing the peptides produced by digestion with trypsin, lysylendopept idase, or pepsin of reduced S-carboxymethylated or S-aminoethylated CB 1. The sequences of fragments CB2 and CB3 were established by sequenci ng the tryptic peptides from reduced S-carboxymethylated CB2 and CB3, and by aligning them with the sequence of rye seed chitinase-c (RSC-c) to maximize sequence homology. The complete amino acid sequence of RS C-a was established by connecting these three fragments. RSC-a consist s of 302 amino acid residues including hydroxyproline residues, and ha s a molecular mass of 31,722 Da. RSC-a is basic protein with a cystein e-rich amino terminal domain, indicating that this enzyme belongs to c lass I chitinases. The amino acid sequence of RSC-a showed that the se quence from Gly60 to C-terminal Ala302 in this enzyme corresponds to t hat of RSC-c belonging to class II chitinases with 92% identity, and t hat RSC-a has high similarity to other plant class I chitinases but a longer hinge region and an extra disulfide bond.