Indirect colorimetric analyses of released reducing groups, as an indicator
of induced beta-1,3-glucanase activities, tend to be the assay methods of
choice for the characterization of plant endo- and exo-beta-1,3-glucanase,
However, interfering low molecular weight reducing sugars found in unproces
sed plant extracts often mask in vitro estimations of P-ld-glucanase activi
ty. The enzyme-catalysed hydrolysis of an optically active beta-1,3-glucan
polymer was monitored polarimetrically by measuring changes in the rotation
of plane-polarized light of the reaction assay medium. A direct, non-radio
chemical assay that detects changes in the optical rotation of released (1-
>3) beta-D-oligoglucosides with low degrees of polymerisation (<<25) has be
en found to be highly reproducible, rapid (total analysis time 15 min), sen
sitive (detection limit 0.007 unit/mL glucanase), selective and non-destruc
tive. This assay has been used to detect a salicylate-induced cell wall-bou
nd tomato beta-1,3-glucanase, which is a component of a pathogenesis-relate
d response in plants. Copyright (C) 2000 John Wiley & Sons, Ltd.