ABSTRACT
Buffalo milk galactosyltransferase is a single poly-peptide of molecular weight 55,000 to 56,000. The enzyme is specific for glucose as an acceptor substrate in the presence of ∝-lactalbumin, L-Arabinose. L-xylose, D-ribose and D-fructose did not serve as acceptor substrates even at concentration as high as 0.13 Μ, while N-acetylglucosamine and ovalbumin served as good acceptors of galactosyl moiety in the absence of ∝ -lactalbumin. UDP-galacturonic acid did not serve as a donor substrate; on the contrary, it inhibited the reaction. Lactose synthetase reaction was inhibited by D-ribose, L-arabinose and L-xylose, whereas D-fructose did not show any inhibition. Buffalo milk ∝ -lactalbumin enhanced the synthesis of lactose but inhibited the synthesis of N-acetyllactosamine. Cations like Ca2+ , Mg2+ , Cu2+ , Ba2+ and Co2+ could not replace Mn2+ in the N-acetyllactosamine synthetase reaction. Except Co2+ , these cations had no effect on this reaction. Co2+ was found to be a competitive inhibitor of Mn2+ . The observed inhibition of the reaction by·EDTA also confirmed the absolute requirement of Mn2+ for the reaction. Lactose synthetase reaction had an optimum pH of 8.5, whereas N-acetyllactosamine synthetase reaction was maximal at pH 8.0.