Lactose Hydrolysis
Lactose hydrolysis

An important application of immobilized enzymes

The main purpose of using immobilized enzymes here is to convert the disaccharide lactose via hydrolysis into its monosaccharide components, glucose and galactose. Lactose is a disaccharide that occurs naturally in both human and cow's milk. It is widely used in baking and in commercial infant-milk formulas.

One large problem with lactose is that many people are lactose intolerant - meaning that their body is incapable of digesting lactose. So it must be hydrolyzed into its monosaccharide components, allowing digestion which is the purpose of products today such as LACTAID.

Like cellobiose and maltose, lactose is a reducing sugar. It exhibits muta - rotation and is a 1,4'-beta-linked glycoside. Unlike cellobiose and maltose, however, lactose contains two dif~erent monosaccharide units. Acidic hydrolysis of lactose yields 1 equiv of D-glucose and 1 equiv of D-galactose; the two are joined by a beta-glycoside bond between C1 of galactose and C4 of glucose. In other words, 100 g of lactose will produce 50g each of galactose and glucose.

Lactose, a 1,4'-beta-glycoside
[4-0 -(beta-D-Galactopyranosyl)-beta-D-glucopyranose]

You may prefer the Haworth formula:

Throughout the processing of milk, the disaccharide lactose accumulates in estimated 1.2 million tons annually from the dairy by-product, cheese whey. The hydrolytic conversion of lactose to glucose and galactose represents one way ofadding value to whey and whey-derived products. For the enzymatic lactose hydrolysis various mesophilic -glycosidases have been described, some of which have already made it to the market. The application of known glycosidases is however partly hampered because of the moderate thermal stability and narrow pH profile of enzyme activity as well as due to the significant inhibition by galactose. The use of hydrolases from thermophilic microorganisms could help to overcome at least some of these problems.

This page done by Scott Poplawski for Biochem Eng. semester project fall '97