Properties of two high-molecular-mass forms of glyceraldehyde-3-phosphate dehydrogenase from spinach leaf, one of which also possesses latent phosphoribulokinase activity

Eur J Biochem. 1991 Dec 18;202(3):1239-46. doi: 10.1111/j.1432-1033.1991.tb16496.x.

Abstract

Two high-Mr forms of chloroplast glyceraldehyde-3-phosphate dehydrogenase from spinach leaf can be separated by DEAE-cellulose chromatography. One form, the high-Mr glyceraldehyde-3-phosphate dehydrogenase, resembles an enzyme previously described [Yonuschot, G.R., Ortwerth, B.J. & Koeppe, O.J. (1970) J. Biol. Chem. 245, 4193-4198]. The other, a glyceraldehyde-3-phosphate dehydrogenase/phosphoribulokinase complex, is characterised by possession of latent phosphoribulokinase activity, only expressed following incubation with dithiothreitol. This complex is composed not only of subunits A (39.5 kDa) and B (41.5 kDa) characteristic of the high-Mr glyceraldehyde-3-phosphate dehydrogenase, but also of a third subunit, R (40.5 kDa) comigrating with that from the active phosphoribulokinase of spinach. Incubation of the complex with dithiothreitol markedly stimulated both its phosphoribulokinase and NADPH-dependent dehydrogenase activities. This dithiothreitol-induced activation was accompanied by depolymerisation to give two predominantly NADPH-linked tetrameric glyceraldehyde-3-phosphate dehydrogenases (the homotetramer, A4, and the heterotetramer, A2B2) as well as the active dimeric phosphoribulokinase. Incubation of the high-Mr glyceraldehyde-3-phosphate dehydrogenase with dithiothreitol promoted complete depolymerisation yielding only the heterotetramer (A2B2). Possible structures suggested for the glyceraldehyde-3-phosphate dehydrogenase/phosphoribulokinase complex are (A2B2)2A4R2 or (A2B2)(A4)2R2.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Blotting, Western
  • Chromatography, DEAE-Cellulose / methods
  • Chromatography, Liquid / methods
  • Electrophoresis, Polyacrylamide Gel
  • Glyceraldehyde-3-Phosphate Dehydrogenases / isolation & purification*
  • Glyceraldehyde-3-Phosphate Dehydrogenases / metabolism*
  • Isoenzymes / isolation & purification*
  • Isoenzymes / metabolism*
  • Kinetics
  • Macromolecular Substances
  • Molecular Weight
  • Phosphotransferases (Alcohol Group Acceptor)*
  • Phosphotransferases / isolation & purification*
  • Phosphotransferases / metabolism*
  • Plants / enzymology*

Substances

  • Isoenzymes
  • Macromolecular Substances
  • Glyceraldehyde-3-Phosphate Dehydrogenases
  • Phosphotransferases
  • Phosphotransferases (Alcohol Group Acceptor)
  • phosphoribulokinase