Melibiase

Solanum indicum L. Niu Zi Qie (Indian nightshade) (root, leaf, fruit) Diosgenin, solanidine, solanine, solasodine, alkaloids, carbohydrases, maltase, saccharase, melibiase.50 Antidote for poison, for urinary disease. 

Of the glycosidases that are important for hydrolyzing exogenously supplied glycosides, /3-D-fructofuranosidase (invertase) and a-D-galac-tosidase (melibiase) activities are well known to occur outside the... 

The a-D-galactopyranosidases are usually known as melibiases, in that melibiose is the most available substrate hydrolyzed specifically by a-D-galactopyranosidase. Melibiases have been encountered (see Table IV) in yeast,10 bacteria, molds, higher plants,36 and a few lower animals,37... 

The classical source for melibiase is almond emulsin. The melibiase activity in almond emulsin is low, and it is easily and preferentially destroyed by alcohol precipitation and by other common preparative steps. Almond melibiase preparations are quite free from invertase,16 and hence they are of special value in those situations where an invertase-free... 

A relatively more active source of melibiase is crude invertase from brewers yeast. Yeast melibiase is nearly free from /J-D-galactosidase, but it contains /3-D-mannosidase as well as /3-D-fructofuranosidase.23... 

Other sources of melibiase are the seeds of alfalfa,39 guar,40 coffee (unroasted),41 and pine42 barley malt36 cultures of Aspergillus oryzae36 and the intestinal juice of snails.37... 

When acted upon by invertase preparations containing melibiase (from brewers yeast), all the raffinose oligosaccharides, including planteose, are hydrolyzed to monosaccharides.23,42... 

Conditions necessary for the reversal of hydrolytic action have been applied by French to the synthesis of small amounts of galactobiose and galactotriose (isolated in crystalline form).33 The reactions catalyzed by yeast melibiase are as follows. 

Synthesis of manninotriose and a higher oligosaccharide,33 by trans-galactosylase action of yeast melibiase on melibiose, has already been noted in a preceding paragraph. 

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