Metabolism galactose

Galactose is isomerized to glucose by UDP-galactose-4-epimerase in what may be the rate-limiting step in galactose metabolism. The reaction, which is freely 

CHAPTER 15 Carbohydrate Metabolism II Gluconeogenesis, Glycogen Synthesis and Breakdown, and Alternative Pathways 

Glucose -phosphate Phospho-gluco-mutase Glucose 6-phosphate 

Metabolic pathway of galactose. Inherited defects that lead to galactosemia. 

Deficiency of the transferase causes a more severe form of galactosemia. Symptoms include cataracts, vomiting. 

This extremely rare disorder exhibits clinical findings similar to transferase deficiency. 

This is a milder condition manifested predominantly by cataracts caused by galactitol deposits in the lens. The diagnosis is confirmed by demonstrating normal transferase activity and no galactokinase in red blood cells. 

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Segal and Blair (S13) have shown that aldehydes reduce NAD to NADH2 in the presence of aldehyde dehydrogenase progesterone, menthol, and menthone inhibit this enzyme and this may account for the stimulatory action shown by these substances on galactose metabolism in vitro. 

The galactose-l-phosphate uridyl transferase pathway is by far the most important in galactose metabolism it accounts for about 5/6 of the total galactose metabolized in mammals. It is less active in the newborn than in the adult, e.g., the liver of newborn rats has only 1/5 the adult amount of galactose-l-phosphate uridyl transferase per milligram of protein (13). 

Subject Liver homogenate ((imoles 1-C14-Gal-1-P incorporated into nu-eleotides/g liver/hour) Erythrocyte hemolyzate (nmoles UDPG utilized/ml red blood cells/hour) In vivo galactose metabolism (g/hour)... 

The effect of some steroid hormones on galactose metabolism in galactosemics did, at one time, raise the hope that some alternative to a low-galactose diet might be effective (E3). Menthol and menthone have a similar effect (see above, Section 3.2). 

Isselbacher, K. J., Evidence for an accessory pathway of galactose metabolism in mammalian liver. Science 126, 652-654 (1957). 

P8. Fesch, L. A., Segal, S., and Topper, Y. J., Progesterone effects on galactose metabolism in prepubertal patients with congenital galactosemia and in rats main-tamed on high galactose diets. J. Clin. Invest. 39, 178-184 (1960). 

Fructose and mannose metabolism Galactose metabolism Ascorbate and aldarate metabolism Pyruvate metabolism Glyoxylate and dicarboxylate metabolism... 

Bissett, D.L. Anderson, R.L. Lactose and D-galactose metabolism in Staphylococcus aureus. Ill Purification and properties of D-tagatose-6-phosphate kinase. J. Biol. Chem., 255, 8745-8749 (1980)... 

Schleifer, K.H. Hartinger, A. Gotz, F. Occurence of D-tagatose-6-phosphate pathway of D-galactose metabolism among Staphylococci. FEMS Microbiol. Lett., 3, 9-11 (1978)... 

Novelll, G. Reichardt, J.K. (2000) Molecular basis of disorders of human galactose metabolism past, present, and future. 

The Genes of Galactose Metabolism in Yeast Are Subject to Both Positive and Negative Regulation... 

TABLE 28-3 Genes of Galactose Metabolism in Yeast nhmmnsnmal Protein size (number of residues) Relative protein expression in different carbon sources ... 

I It is physiologically unimportant 1 in galactose metabolism unless j galactose levels are high (as in galactosemia). 

Bissett, D. L. and Anderson, R. L. 1973. Lactose and D-galactose metabolism in Staphylococcus aureus Pathway of D-galactose 6-phosphate degradation. Biochem. Bio-phys. Res. Commun. 52, 641-645. 

In the induction of enzymes of galactose metabolism in E. coli, three enzymes are involved -galactosidase (which catalyses the hydrolysis of the y -glycosidic bonds of lactose), galactose permease (which is responsible for transport of lactose across the cell membrane) and a third enzyme, A-protein, apparently not directly involved in galactose metabolism. The system has an environmental inducer, galactose, and in its presence the number of /)-galactosidase molecules rises from 5-10 to 10,000 within the cell. The addition of the inducer can increase the protein production in less than five minutes after its addition. Protein synthesis of these enzymes stops almost immediately in the absence of lactose. 

Gene Regulation in Yeast A Unicellular Eukaryote Galactose Metabolism Is Regulated by Specific Positive and Negative Control Factors in Yeast The GAL4 Protein Is Separated into Domains with Different Functions... 

Galactose Metabolism Is Regulated by Specific Positive and Negative Control Factors in Yeast... 

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