LACTOSE SYNTHESIS I. THE DISTRIBUTION OF Cl4 IN LACTOSE OF MILK AFTER INTRAVENOUS INJECTION OF Cl4 COMPOUNDS* BY PER SCHAMBYE,t
نویسنده
چکیده
Glucose of the blood has been considered to be the major source of the carbon of lactose in milk, and recent studies with labeled glucose have substantiated this conclusion. Kleiber et al. (1) injected’ glucose-U-C4 intravenously into a lactating cow and found approximately 50 per cent of the Cl4 converted to milk lactose. They calculated that about four-fifths of the lactose carbon originated from plasma glucose or a pool of metabolites which were rapidly interconverted with plasma glucose. Similar conclusions were reached by Reiss and Barry (2) from studies with a goat given glucose-C14. According to previous evidence, the transformation of glucose to lactose may be considered to occur as follows:
منابع مشابه
Lactose synthesis. II. The distribution of C14 in lactose of milk from the perfused isolated cow udder.
The distribution of Cl4 in milk lactose after intravenous injection of various labeled compounds has been determined by Schambye, Wood, and Kleiber (l), who found that the Cl4 pattern of the glucose differed from that of the galactose particularly when acetate-l-Cl4 or NaHC403 was administered. They proposed that free glucose (in equilibrium with blood glucose) was the precursor of the glucose ...
متن کاملLactose synthesis. V. C14 in lactose, glycerol, and serine as indicators of the triose phosphate isomerase reaction and pentose cycle.
Previous studies have indicated that blood glucose is the major precursor of both the glucose and galactose moieties of milk lactose. The Cl4 distribution patterns of the two moieties differ, however, and it appears that the glucose and the galactose moieties arise from the different precursors (l-4). It also has been suggested that the unsymmetrical distribution of Cl4 found in the galactose m...
متن کاملButyrate Metabolism in the Lactating Cow S-
The possibility that butyrate may be glucogenic in ruminants has been suggested by several experimental studies. Intravenous injection of butyrate in sheep was followed by increased concentrations of blood sugar (1) and, in lambs, it was found that butyrate was more effective than propionate for alleviating insulin-induced hypoglycemia (2) ; acetate injection did not have a similar effect in ei...
متن کاملComparison of the metabolism of C14-labeled lactose, glucose, and galactose in rats.
The importance of milk in human nutrition makes it desirable to understand better the metabolism of lactose. Much of the experimental work on the utilization of lactose has been conducted with rats (8, 16). Other investigators have employed pigs, chickens, dogs, and calves (10-12, 19), while infants, children, and adults were used under suitable conditions (2, 14, 21, 23). We wish to report her...
متن کاملBiosynthesis of Fucosyllactose and Other Oligosaccharides Found in Milk.
The carbohydrate fraction of human milk includes a number of chemically defined oligosaccharides which contain the 6-deoxyhexose, L-fucose (2, 3). The present report describes a particulate enzyme from lactating canine mammary tissue’ which catalyzes the synthesis of fucosyllactose,2 the simplest member of this group, by transfer of L-fucose from guanosine diphosphate L-fucose to lactose. If fu...
متن کامل