Some properties of a beta-galactosidase from an extremely thermophilic bacterium.

An inducible beta-galactosidase from an extremely thermophilic organism, Thermus strain 4-1A, has been isolated and partially purified. There were significant dissimilarities to T. aquaticus beta-galactosidase. It had a pl of 4.5, was inhibited by sulphydryl inhibitors and a number of transition metals, and was activated by EDTA and SH-containing reagents. The beta-galactosidase showed strong product inhibition, and weaker inhibition by some other mono- and disaccharides. It was very stable up to 90 degrees C at pH 8. On immobilization by diazonium linkage to porous glass, the pH optimum (6.0), the K(M) with ONPG (5mM) and the product inhibition were not altered.