Skip to main content
Biochemical Journal logoLink to Biochemical Journal
. 1965 Sep;96(3):607–615. doi: 10.1042/bj0960607

Estimation of the pentose cycle in the perfused cow's udder

Harland G Wood 1, Georges J Peeters 1, Roger Verbeke 1, Monique Lauryssens 1, Birgit Jacobson 1
PMCID: PMC1207194  PMID: 5862402

Abstract

1. The distributions of 14C have been compared in the glucose and galactose moieties of lactose obtained from cows' udders perfused with blood containing [1-14C]-, [2-14C]- and [6-14C]-glucose. The 14C of the glucose moiety was found in the same position as that of the administered glucose, but in the galactose moiety the 14C from [2-14C]glucose was extensively randomized into positions 1 and 3. It is concluded that the glucose moiety arose from free glucose and the galactose moiety from hexose phosphate intermediates and that the latter reflected the randomization occurring through reactions of the pentose cycle. 2. The proportion of the glucose metabolized via the pentose cycle for those cells making lactose was estimated from the distribution of 14C in the galactose moiety and found to be about 23% in one experiment and 30% in another experiment. 3. The yield and distribution of 14C were determined in the glycerol of fat from the tissue in experiments with [2-14C]- and [6-14C]-glucose. There was a greater randomization of 14C in the glycerol than in C-1, C-2 and C-3 of the galactose moiety of lactose. The ratio of the yield of 14C in the glycerol from [2-14C]glucose to that of [6-14C]glucose was very low and from this ratio it was calculated that less than 10% of the glucose was metabolized by the Embden–Meyerhof pathway and approx. 60–70% was converted into lactose. 4. [6-14C]Glucose and [6-3H]glucose were used to determine whether the 3H at the C-6 position remained stable during its conversion into glyceride of fat from the tissue. Twenty-seven per cent of the 3H was labilized during this conversion. Therefore it was not possible to use [2-14C]glucose and [6-3H]glucose in a single experiment to measure the relative conversion of the C-2 and C-6 positions of glucose to glycerol.

Full text

PDF
609

Selected References

These references are in PubMed. This may not be the complete list of references from this article.

  1. ABRAHAM S., CADY P., CHAIKOFF I. L. Effect of insulin in vitro in pathways of glucose utilization, other than Embden-Meyerhof, in rat mammary gland. J Biol Chem. 1957 Feb;224(2):955–962. [PubMed] [Google Scholar]
  2. BLACK A. L., KLEIBER M., BUTTERWORTH E. M., BRUBACHER G. B., KANEKO J. J. The pentose cycle as a pathway for glucose metabolism in intact lactating dairy cows. J Biol Chem. 1957 Jul;227(1):537–550. [PubMed] [Google Scholar]
  3. GLOCK G. E., McLEAN P. Levels of enzymes of the direct oxidative pathway of carbohydrate metabolism in mammalian tissues and tumours. Biochem J. 1954 Jan;56(1):171–175. doi: 10.1042/bj0560171. [DOI] [PMC free article] [PubMed] [Google Scholar]
  4. GLOCK G. E., McLEAN P. Levels of enzymes of the direct oxidative pathway of carbohydrate metabolism in the mammary gland of the rat. Biochim Biophys Acta. 1953 Dec;12(4):590–590. doi: 10.1016/0006-3002(53)90195-4. [DOI] [PubMed] [Google Scholar]
  5. GLOCK G. E., McLEAN P. Pathways of glucose utilization in mammary tissue. Proc R Soc Lond B Biol Sci. 1958 Dec 17;149(936):354–362. doi: 10.1098/rspb.1958.0075. [DOI] [PubMed] [Google Scholar]
  6. HANSEN R. G., WOOD H. G., PEETERS G. J., JACOBSON B., WILKEN J. Lactose synthesis. VI. Labeling of lactose precursors by glycerol-1,3-C-14 and glucose-2-C-14. J Biol Chem. 1962 Apr;237:1034–1039. [PubMed] [Google Scholar]
  7. KATZ J., WOOD H. G. The use of glucose-C14 for the evaluation of the pathways of glucose metabolism. J Biol Chem. 1960 Aug;235:2165–2177. [PubMed] [Google Scholar]
  8. KLEIBER M., BLACK A. L., BROWN M. A., BAXTER C. F., LUICK J. R., STADTMAN F. H. Glucose as a precursor of milk constituents in the intact dairy cow. Biochim Biophys Acta. 1955 Jun;17(2):252–260. doi: 10.1016/0006-3002(55)90357-7. [DOI] [PubMed] [Google Scholar]
  9. LANDAU B. R., BARTSCH G. E., KATZ J., WOOD H. G. ESTIMATION OF PATHWAY CONTRIBUTIONS TO GLUCOSE METABOLISM AND OF THE RATE OF ISOMERIZATION OF HEXOSE 6-PHOSPHATE. J Biol Chem. 1964 Mar;239:686–696. [PubMed] [Google Scholar]
  10. LANDAU B. R., KATZ J. A QUANTITATIVE ESTIMATION OF THE PATHWAYS OF GLUCOSE METABOLISM IN RAT ADIPOSE TISSUE IN VITRO. J Biol Chem. 1964 Mar;239:697–704. [PubMed] [Google Scholar]
  11. POPJAK G., GLASCOCK R. F., FOLLEY S. J. Incorporation of [carboxy-14C] acetate into lactose and glycerol by the lactating goat udder. Biochem J. 1952 Nov;52(3):472–475. doi: 10.1042/bj0520472. [DOI] [PMC free article] [PubMed] [Google Scholar]
  12. REISS O. K., BARRY J. M. The synthesis of lactose from glucose in the mammary gland. Biochem J. 1953 Dec;55(5):783–785. doi: 10.1042/bj0550783. [DOI] [PMC free article] [PubMed] [Google Scholar]
  13. SCHAMBYE P., WOOD H. G., KLEIBER M. Lactose synthesis. I. The distribution of C14 in lactose of milk after intravenous injection of C14 compounds. J Biol Chem. 1957 Jun;226(2):1011–1021. [PubMed] [Google Scholar]
  14. VERBEKE R., LAURYSSENS M., PEETERS G., JAMES A. T. Incorporation of DL-[1-14C]leucine and [1-14C]liso valeric acid into milk constituents by the perfused cow's udder. Biochem J. 1959 Sep;73:24–29. doi: 10.1042/bj0730024. [DOI] [PMC free article] [PubMed] [Google Scholar]
  15. WATKINS W. M., HASSID W. Z. The synthesis of lactose by particulate enzyme preparations from guinea pig and bovine mammary glands. J Biol Chem. 1962 May;237:1432–1440. [PubMed] [Google Scholar]
  16. WOOD H. G., GILLESPIE R., JOFFE S., HANSEN R. G., HARDENBROOK H. Lactose synthesis. V. C14 in lactose, glycerol, and serine as indicators of the triose phosphate isomerase reaction and pentose cycle. J Biol Chem. 1958 Dec;233(6):1271–1278. [PubMed] [Google Scholar]
  17. WOOD H. G., JOFFE S., GILLESPIE R., HANSEN R. G., HARDENBROOK H. Lactose synthesis. IV. The synthesis of milk constituents after unilateral injection of glycerol-1,3-C14 into the pudic artery. J Biol Chem. 1958 Dec;233(6):1264–1270. [PubMed] [Google Scholar]
  18. WOOD H. G., KATZ J., LANDAU B. R. ESTIMATION OF PATHWAYS OF CARBOHYDRATE METABOLISM. Biochem Z. 1963;338:809–847. [PubMed] [Google Scholar]
  19. WOOD H. G., KATZ J. The distribution of C14 in the hexose phosphates and the effect of recycling in the pentose cycle. J Biol Chem. 1958 Dec;233(6):1279–1282. [PubMed] [Google Scholar]
  20. WOOD H. G., SCHAMBYE P., PEETERS G. J. Lactose synthesis. II. The distribution of C14 in lactose of milk from the perfused isolated cow udder. J Biol Chem. 1957 Jun;226(2):1023–1034. [PubMed] [Google Scholar]
  21. WOOD H. G., SIU P., SCHAMBYE P. Lactose synthesis. III. The distribution of C14 in lactose of milk after intra-arterial injection of acetate-1-C14. Arch Biochem Biophys. 1957 Jul;69:390–404. doi: 10.1016/0003-9861(57)90505-2. [DOI] [PubMed] [Google Scholar]

Articles from Biochemical Journal are provided here courtesy of The Biochemical Society

RESOURCES