Galactokinase

Although no drug discovery efforts have been reported to date, Wierenga et al. proposed inhibition of galactokinase for treatment of classic galactosemia and described an assay to screen potential inhibitors.19,20 

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A somewhat more complicated route into glycolysis is followed by galactose, another simple hexose sugar. The process, called the Leloir pathway after Luis Leloir, its discoverer, begins with phosphorylation from ATP at the C-1 position by galactokinase ... 

Reaction (1) is irreversible the enzyme galactokinase has been found in mammalian liver, brain, and erythrocytes, as well as in certain yeasts and other microorganisms. UDPGal, the main product of reaction (2), is the intermediate by means of which the body incorporates galactose into cerebrosides and, probably, other galactolipids, mucopolysaccharides, and lactose galactose-l-phosphate uridyl transferase occurs in the liver, to a lesser extent in red cells, and probably in other tissues. 

It would appear that the specific action of an enzyme upon its substrate is conditioned by a definite chemical structure and spatial arrangement of the constituent polar and non-polar groups of the enzyme protein as well as by the constitution and configuration of the substrate. In some cases an enzyme interacts with one chemical compound only. For example, galactokinase extracted from Saccharomyces fragilis (grown on whey) catalyzes the transphosphorylation between adenosine triphos-... 

Once transported into tissues, galactose is phosphorylated (galactokinase), trapping it in the cell. Galactose 1-phosphate is converted to glucose 1-phosphate by galactose 1-P uridyltrans-ferase and an epimerase. The pathway is shown in Figure 1-12-5 important enzymes to remember are ... 

Galactokinase Deficiency Galactose 1-Phosphate Uridyltransferase Deflcieucy... 

GALACTOSYLCERAMINIDASE GALACTOKINASE GALACTONATE DEHYDRATASE GALACTOSE 1-DEHYDROGENASE GALACTOSE OXIDASE... 

In the cell, galactose is converted to galactose 1-phosphate by galactokinase with ATP as the phosphate donor. 

Elevated in deficiencies of galactokinase, galactose-1-phosphate uridyltransferase (classical galactosemia), UDP galactose-4-epimerase, and Fanconi-Bickel-syn drome, portocaval shunt, and cirrhosis, depending on time after lactose consumption. 

Galactokinase is the enzyme deficient in galactokinase deficiency (MIM 230 200). This disorder is caused by impairment of the pathway step from galactose to galactose-1 -phosphate. 

Table 4.6.1 Reagent mix for detection of galactokinase deficiency. BME (2-Mercaptoethanol)...

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