Indole-3-acetic acid at 10μM caused a 30%decrease in the weight-average molecular mass of xyloglucans extracted with 24%KOH from the cell walls of epicotyl segments of azuki bean (Vigna angularisOhwi et Ohashi cv. Takara). Concanavalin A (Con A) at 2 g liter−1completely inhibited the IAA-induced change in the molecular mass of the xyloglucans. Con A also suppressed the autolysis of pectin-depleted cell walls, as well as the breakdown of xyloglucans by a protein fraction that had been extracted with 1 M NaCl from the cell walls of azuki bean epicotyls. These results indicate that Con A is a potent inhibitor of the breakdown of xyloglucans both in vivo and in vitro. Most of the activity responsible for the decrease in staining by iodine and the increase in reducing power of solution of xyloglucans in the protein fraction from cell walls bound to a column of Con A-Sepharose and was eluted by the specific hapten, methylα-D-mannopyranoside. It seems, therefore, that glycoprotein enzymes may be involved in the breakdown of xyloglucans in the cell walls of azuki bean epicot
展开▼
