Yj. Kim et Bk. Hwang, PURIFICATION, N-TERMINAL AMINO-ACID SEQUENCING AND ANTIFUNGAL ACTIVITY OF CHITINASES FROM PEPPER STEMS TREATED WITH MERCURIC-CHLORIDE, Physiological and molecular plant pathology, 48(6), 1996, pp. 417-432
Different isoforms of chitinases were purified from pepper (Capsicum a
nnuum L. cv. Hanbyul) stems treated with mercuric chloride. The acidic
isoform a1 (69 kDa, pI 5.0), basic isoforms b1 (32 kDa, pI 9.0) and b
2 (22 kDa, pI 9.1) were purified by chitin-affinity chromatography, wi
th subsequent electroelution from nondenaturing polyacrylamide gel ele
ctrophoresis (PAGE) gels. The acidic isoform al has chitin-binding pro
perties, but no antifungal activity. The basic isoforms b1 and b2 cont
ain high ratios of cysteine and glycine at the N-terminal chitin-bindi
ng domain, exhibit chitinase activity, and show antifungal activities
against Colletotrichum gloeosporioides, Fusarium oxysporum f. sp. cucu
merinum, Magnaporthe grisea, and Trichoderma viride in vitro. Moreover
, their antifungal activity shows a high degree of specificity to fila
mentous fungi. The chitinases b1 and b2 show a high sequence identity
in their N-terminal residues with those from wheat, tobacco, potato, r
ice and Arabidopsis thaliana. None of the purified isoforms of chitina
ses inhibited hyphal growth of the Oomycete fungus which lacks chitin
Phytophthora capsici. In contrast, zoospore germination and germ tube
elongation of P. capsici were effectively inhibited by treatment with
b1 and b2. (C) 1996 Academic Press Limited