[医] 乳糖

Lactin \Lac"tin\, n. [L. lac, lactis, milk: cf. F. lactine. Cf.
{Galactin}.] (Physiol. Chem.)
See {Lactose}.

lactose \lac"tose`\ (l[a^]k"t[=o]s`), n.
1. (Physiol. Chem.) The main sugar present in milk, called
also {sugar of milk} or {milk sugar}. When isolated pure
it is obtained crystalline; it is separable from the whey
by evaporation and crystallization. It is a disaccharide
with the formula {C12H22O11}, being chemically
4-([beta]-D-galactosido)-D-glucose. It has a slightly
sweet taste, is dextrorotary, and is much less soluble in
water than either cane sugar or glucose. Formerly called
{lactin}. When hydrolyzed it yields glucose and galactose.
In cells it may be hydrolyzed by the enzyme
[beta]-galactosidase.
[1913 Webster +PJC]

2. (Chem.) See {Galactose}.