Pyruvate is a by-product of Rubisco catalysis

Conference · Tue May 01 04:00:00 EDT 1990 · Plant Physiology, Supplement; (USA)

OSTI ID:5724846

Andrews, T J; Kane, H J ^[1]

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1. Australian National Univ., Canberra (Australia)

The catalytic mechanism of D-ribulose-1,5-bisphosphate (RuBP) carboxylase (Rubisco) involves several enzyme-bound intermediates. The 2,3-enediol resulting from abstraction of the C-3 proton from RuBP, and the 6-carbon intermediate resulting from its carboxylation, are well established. However, the C-2 carbanion form of 3-phosphoglycerate, thought to be produced by scission of the bond between C-2 and C-3 of the gem-diol form of the 6-carbon intermediate, is less well documented. We have observed the formation of ({sup 14}C)pyruvate during catalysis by purified spinach Rubisco in the presence of {sup 14}CO{sub 2} to an extent of approximately 1% of the total {sup 14}C fixed at substrate saturation and pH 8. Pyruvate formation was also continuously measured spectrophotometrically in the presence of lactate dehydrogenase and NADH. No pyruvate was formed when 3-phosphoglycerate was substituted for RuBP or when Rubisco was inhibited by a reaction-intermediate analog. Pyruvate is the expected product of {beta}-elimination of the phosphoryl moiety of the acid carbanion, either at the active site or in solution after release from the enzyme. These observations establish the intermediacy of the carbanion species and provide yet another example of Rubisco's catalytic inefficiency.

• OSTI ID: 5724846
• Report Number(s): CONF-9007196--
• Conference Information: Journal Name: Plant Physiology, Supplement; (USA) Journal Volume: 93:1
• Country of Publication: United States
• Language: English

Related Subjects

550501* -- Metabolism-- Tracer Techniques
59 BASIC BIOLOGICAL SCIENCES
BIOSYNTHESIS
CARBON 14 COMPOUNDS
CARBON-CARBON LYASES
CARBOXY-LYASES
CARBOXYLIC ACIDS
CATALYSIS
ENZYMES
FOOD
ISOTOPE APPLICATIONS
KETO ACIDS
LABELLED COMPOUNDS
LYASES
MAGNOLIOPHYTA
MAGNOLIOPSIDA
ORGANIC ACIDS
ORGANIC COMPOUNDS
PLANTS
PYRUVIC ACID
RIBULOSE DIPHOSPHATE CARBOXYLASE
SPINACH
SYNTHESIS
TRACER TECHNIQUES
VEGETABLES