ISOFORMS OF LINAMARASE IN CASSAVA (MANIHOT-ESCULENTA)

Linamarase (EC. 3.2.1.21) was purified from different tissues of cassa va (leaf, rind and tuber) to compare the kinetic properties and charac teristics of the enzyme in these tissues. Purified enzyme preparation appeared as single band of average molecular size 70 kD in SDS-PAGE ge ls. The kinetic properties of linamarase with respect to pH and temper ature indicated that tuber linamarase possessed a broader pH optimum a nd higher temperature stability as compared to leaf and rind enzymes. Differences in Km values for linamarin were observed with leaf linamar ase having the highest Km value (500 mu M) followed by rind (400 mu M) and then tuber (250 mu M) linamarases. Rind enzyme appeared to be les s susceptible to urea denaturation than the leaf enzyme. Comparison of elution profiles from DEAE-Cellulose indicated that the relative amou nts of the various ionic forms of the enzyme differed in the case of e ach tissue. Elution patterns of the enzyme from Con A-Sepharose also d iffered, suggesting difference in glycosylation among leaf, rind and t uber enzymes. This was confirmed by carbohydrate analysis which showed that the tuber linamarase contained significantly higher amount of pr otein bound carbohydrate. These results suggest the possible occurrenc e of different forms of linamarase in cassava.