Phosphoglycolate phosphatase of spinach acts as a phosphoenzyme
When /sup 32/P-glycolate and phosphoglycolate phosphatase from spinach are mixed, /sup 32/P is incorporated into acid precipitated protein. Properties that relate this phosphorylation to the enzyme are: The K/sub m/ value for P-glycolate is similar for protein phosphorylation and substrate hydrolysis; the /sup 32/P appearing in the phosphoenzyme is diluted by unlabeled P-glycolate or the alternative substrate, ethyl-P; the activator Cl/sup -/ enhances the effectiveness of ethyl-P as a substrate and as an inhibitor of the formation of /sup 32/P-enzyme; and /sup 32/P is lost from the enzyme when /sup 32/P-glycolate is consumed. The acid denatured phosphorylated protein is a molecule of 34,000 Da, which is half of the molecular weight of the native protein and is similar in size to the labeled band that is seen on SDS-polyacrylamide gels. The enzyme-bound phosphoryl group appears to be an acyl-phosphate from its pH stability, being quite stable at pH 1, less stable at pH 5, and very unstable above pH 5. The bond is readily hydrolyzed in acid molybdate and it is sensitive to cleavage by hydroxylamine at pH 6.8. The demonstration of enzyme phosphorylation by /sup 32/P-glycolate resolves the dilemma presented by initial rate studies in which alternative substrates appeared to have different mechanisms.
- Research Organization:
- Institute for Cancer Research, Philadelphia, PA
- OSTI ID:
- 6173334
- Report Number(s):
- CONF-870644-
- Journal Information:
- Fed. Proc., Fed. Am. Soc. Exp. Biol.; (United States), Vol. 46:6; Conference: 78. annual meeting of the American Society of Biological Chemists conference, Philadelphia, PA, USA, 7 Jun 1987
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
PHOSPHATASES
BIOCHEMICAL REACTION KINETICS
PROTEINS
PHOSPHORYLATION
ELECTROPHORESIS
GLYCOLIC ACID
MOLECULAR WEIGHT
PHOSPHORUS 32
SPINACH
TRACER TECHNIQUES
BETA DECAY RADIOISOTOPES
BETA-MINUS DECAY RADIOISOTOPES
CARBOXYLIC ACIDS
CHEMICAL REACTIONS
DAYS LIVING RADIOISOTOPES
ENZYMES
ESTERASES
FOOD
HYDROLASES
HYDROXY ACIDS
ISOTOPE APPLICATIONS
ISOTOPES
KINETICS
LIGHT NUCLEI
MONOCARBOXYLIC ACIDS
NUCLEI
ODD-ODD NUCLEI
ORGANIC ACIDS
ORGANIC COMPOUNDS
PHOSPHORUS ISOTOPES
PLANTS
RADIOISOTOPES
REACTION KINETICS
VEGETABLES
550201* - Biochemistry- Tracer Techniques