SEQUENCE-ANALYSIS OF CONCANAVALIN-B FROM CANAVALIA-ENSIFORMIS REVEALSHOMOLOGY TO CHITINASES

The concanavalin B of Canavalia ensiformis (L.) DC., which constitutes 0.9% of the total seed protein, was isolated and purified by crystall isation. The primary structure was derived from a full-length cDNA clo ne and confirmed by amino acid sequence analysis of the N-terminus and 7 internal peptides. The mature protein comprises 299 amino acids and has a molecular weight of 33,828. The protein sequence exhibits up to 45% sequence identity to several members of family 18 glycosylhydrola ses. However, we could not detect any chitinase activity in our concan avalin B preparations. The lack of activity is most likely due to the replacement of a glutamate residue, present in the putative active sit e of chitinases, by a glutamine residue in concanavalin B. Crystals th at could be used for high resolution X-ray analysis were grown by a pH shift. A complete data set to 0.165 nm was collected.