コイ血液からの二種の酸性β-Ｎ-acetylhexosaminidase isoenzymesの精製およびそれらの性質

Two acidic β-N-acetylhexosaminidase isoenzymes, form-1 and form-2, were purified to an electrophoretically homogeneous from carp white blood cells, and the enzymatic properties of the two purified enzymes were studied. The two forms, form-1 and form-2, had common pH optimum of 5.0, similar Km values of 0.2mM, and the same molecular weights of 116, 000. They were inhibited to a similar extent by N-acetylgalactosamine and N-acetylglucosamine. They showed both β-N-acetylglucosaminidase and β-N-acetylgalactosaminidase activities. The form-1 and form-2 differed in thermostability and electrophoretic mobility. The form-2 was more heat-liable and had more anodic mobility than the form-1. The isoelectric points of the form-1 and form-2 were 6.2 and 4.8, respectively. The form-2 could be converted to a form that resembles the form-1 by neuraminidase treatment. The properties of the two forms in carp blood were similar with those of hexosaminidases A and B in human tissues.