Evidence for orientation-conserved transfer in the TCA cycle in Saccharomyces cerevisiae: 13C NMR studies

Biochemistry. 1993 Nov 30;32(47):12725-9. doi: 10.1021/bi00210a022.


When [4-13C]glutamate is incubated with yeast cells, the [13C]aspartate formed shows a [2-13C]/[3-13C] ratio that is greater than 1. If the conversion occurs through the Krebs TCA cycle with the symmetrical intermediates succinate and fumarate, the ratio is expected to be 1. The addition of fluoroacetate to the incubation increases the ratio further. When the mutants Aco1- or CS1- are used, little or no aspartate is formed. When [2-13C]acetate is incubated with yeast, the C2-/C3-aspartate ratio is 1.5 at 2 min and decrease to 1.0 after 10 min of incubation. These results indicate that orientation-conserved transfer occurs at the succinate thiokinase and succinate dehydrogenase steps of the Krebs TCA cycle.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, Non-P.H.S.
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Acetates / metabolism
  • Acyl Coenzyme A / metabolism
  • Aspartic Acid / metabolism
  • Carbon Isotopes
  • Citric Acid Cycle / genetics
  • Citric Acid Cycle / physiology*
  • Glutamates / metabolism
  • Magnetic Resonance Spectroscopy
  • Models, Biological
  • Mutation
  • Saccharomyces cerevisiae / genetics
  • Saccharomyces cerevisiae / metabolism*


  • Acetates
  • Acyl Coenzyme A
  • Carbon Isotopes
  • Glutamates
  • Aspartic Acid
  • succinyl-coenzyme A