Galactosemia is a rare autosomal recessive disorder due to a deficiency of galactose-1-P:uridyl transferase (GALT) (classical galactosemia), galactokinase (GALK), or UDP-galactose-4 epimerase (GALE). Of the three, GALT deficiency is the most severe and results in the accumulation of galactose-1-P in tissues, which damages the liver, eye, brain, ovary, and kidney. In GALK deficiency, ingested ga...

A preadaptive purely aerobic utilization of galactose by yeast cells has been demonstrated. Hence, the adaptation by yeast to galactose is not to its utilization per se, but specifically to its metabolism by a glycolytic mechanism. An examination of this preadaptive oxidation of galactose reveals that it has many characteristics in common with the endogenous metabolism of yeast. Included among ...

The effect of increased glycogenolysis, simulated by galactose's conversion to glucose, on the contribution of gluconeogenesis (GNG) to hepatic glucose production (GP) was determined. The conversion of galactose to glucose is by the same pathway as glycogen's conversion to glucose, i.e., glucose 1-phosphate --> glucose 6-phosphate --> glucose. Healthy men (n = 7) were fasted for 44 h. At 40 h, ...

Galactokinase (GalK) catalyses the first step of the Leloir pathway of galactose metabolism, the ATP-dependent phosphorylation of galactose to galactose-1-phosphate. In man, defects in galactose metabolism can result in disorders with severe clinical consequences, and deficiencies in galactokinase have been linked with the development of cataracts within the first few months of life. The crysta...

BACKGROUND/AIMS Previous studies from our laboratory have revealed impaired intestinal absorption of D-galactose in lipopolysaccharide-treated rabbits. The aim of the present work was to examine the effect of LPS on D-galactose intestinal absorption in vitro. METHODS D-galactose intestinal transport was assessed employing three techniques: sugar uptake in rings of everted jejunum, transepithe...

BACKGROUND In Saccharomyces cerevisiae galactose is initially metabolized through the Leloir pathway after which glucose 6-phosphate enters glycolysis. Galactose is controlled both by glucose repression and by galactose induction. The gene PGM2 encodes the last enzyme of the Leloir pathway, phosphoglucomutase 2 (Pgm2p), which catalyses the reversible conversion of glucose 1-phosphate to glucose...

A novel, systematic approach was used to identify amino acid residues responsible for substrate recognition in the transmembrane 10 region of the Gal2 galactose transporter of Saccharomyces cerevisiae. A mixture of approximately 25,000 distinct plasmids that encode all the combinations of 12 amino acids in transmembrane 10 that are different in Gal2 and the homologous glucose transporter Hxt2 w...

Phosphorylation of free galactose by lactic streptococci was mediated by an adenosine triphosphate (ATP)-dependent kinase. The phosphoenolpyruvate (PEP) phosphotransferase system (PTS) was involved to a limited extent in transport of the sugar. The conversion of free galactose to glucose also was demonstrated, and uridine diphosphogalactose-4-epimerase was demonstrated to account for this chang...

In a previous study, system level analysis of adaptively evolved yeast mutants showing improved galactose utilization revealed relevant mutations. The governing mutations were suggested to be in the Ras/PKA signaling pathway and ergosterol metabolism. Here, site-directed mutants having one of the mutations RAS2(Lys77), RAS2(Tyr112), and ERG5(Pro370) were constructed and evaluated. The mutants w...

BACKGROUND The pathophysiological mechanisms underlying premature ovarian failure (POF) are largely unknown. Our objective was to develop a working animal model to explore the pathogenesis of POF. Since galactosaemic women eventually develop POF, we evaluated the potential of experimental galactose toxicity as the proposed model. METHODS Pregnant rats were fed pellets supplemented with or wit...