Plant beta galactosidases

¿-galactosidases belong to glycosyl hydrolase family of enzymes.These enzymes are widely distributed in nature.¿-galactosidases have been implicated in many biological functions like hydrolysis of dietary lactose,degradation of glycolipids and proteoglycans,fruit ripening, cell elongation, storage mobilisation and petal senescence. ¿ - galactosidase has proven as a best alternative for elimination of lactose intolerance.The present study was aimed at investigating the biochemical properties of ¿-galactosidases from apricots.Three isoenzymes(¿¿gal I,¿¿gal II and ¿¿gal III) were obtained by salt fractionation and ion-exchange and Sephadex G-100 column chromatography. ¿-gal I,II and III showed 0.39, 0.52 and 0.30 units of activity respectively. The molecular weight of ¿¿gal I,II an III as determined by gel filtration was found to be 44.15,34.70 and 23.71 KDa respectively. The optimum pH for the activity of different isozymes was between 4 and 6. The isoenzymes were determined to be thermally stable upto 40oC. The Km for ¿¿gal I was 1.85mM,1.7mM for ¿¿gal II and 1.19 for ¿¿gal III.The Vmax for ¿¿gal I,¿¿gal II aand ¿¿gal III was found to be 0.52,0.70 and 0.38µmole/min respectively.