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 0.38mole/min respectively.