Purification of two basic 1,3-beta-glucanase isoforms from Cyamopsis tetragonoloba (L.) Taub. induced to resist virus infections

1,3-beta -glucanases (EC 3.2.1.39) are enzymes that degrade polysaccharidic substrates and have antimicrobial activity against fungi and bacteria. The y have also been implicated in systemic acquired resistance (SAR) indirectl y through release of endogenous elicitor molecules. SAR against viruses can be induced in plants by a few substances, including proteins isolated from some non-host plants. In the present study, CAP-34, a 34 kDa basic protein isolated from Clerodendrum aculeatum L., was used to induce systemic resis tance against sunnhemp rosette virus in Cyamopsis tetragonoloba (L.) Taub. 1.3-beta -glucanase activity increased rapidly following treatment with CAP -34. The glucanase induction started within 3 h of treatment, and maintaine d a peak value between 6 and 24 h before declining between 48 and 72 h. Two isoforms were purified from resistant C. tetragonoloba. Both were basic ac id possessed an M-r of 34 and 36 kDa Their pI was greater than pH 9.3. pH o ptima were 5.5 and 5.6 fdr the 34 and 36 kDa isoforms, respectively, while their K-m was 400 and 656.6 mug ml(-1). While the total yield of the 35 kDa glucanase was considerably higher than the 34 kDa isoform, its specific ac tivity was less.