Uridine diphosphate glucose dehydrogenase from cornea and epiphysial-plate cartilage.
1. UDP-glucose dehydrogenase (EC 1.1.1.22) was extracted from epiphysial-plate cartilage of newborn pigs and from whole bovine corneas. 2. Formation of UDP-glucuronic acid was demonstrated by radioautography after separation of the sugar nucleotides by paper chromatography or t.l.c.: in these conditions a radioactive glucuronic acid spot also appears. 3. UDP-xylose prevented the formation in the incubation mixture of both UDP-glucuronic acid and free glucuronic acid. 4. In both tissues the dependence of the enzyme activity on pH and the K(m) values for UDP-glucose and NAD(+) were determined. 5. Inhibition by UDP-xylose with respect to UDP-glucose was investigated. The plots of 1/v versus 1/[UDP-glucose], and of percentage inhibition versus UDP-xylose concentration and the Hill coefficient showed that a co-operative effect existed between UDP-xylose-binding sites. 6. The physiological meaning of the different affinities of cartilage and cornea enzymes for UDP-xylose is discussed and related to the different glycosaminoglycan contents of the two connective tissues studied.
D000429:Alcohol Oxidoreductases / Q000037:antagonists & inhibitors / Q000302:isolation & purification / Q000378:metabolism*; D000818:Animals; D000831:Animals, Newborn; D001665:Binding Sites; D002247:Carbon Isotopes; D002356:Cartilage / Q000187:drug effects / Q000201:enzymology*; D002417:Cattle; D002854:Chromatography, Paper; D002855:Chromatography, Thin Layer; D003315:Cornea / Q000187:drug effects / Q000201:enzymology*; D004838:Epiphyses; D005947:Glucose; D005965:Glucuronates; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D013056:Spectrophotometry, Ultraviolet; D013552:Swine; D014539:Uridine Diphosphate Sugars / Q000494:pharmacology; D014994:Xylose / Q000494:pharmacology
D002247:Carbon Isotopes; D005965:Glucuronates; D014539:Uridine Diphosphate Sugars; D014994:Xylose; D000429:Alcohol Oxidoreductases; D005947:Glucose