Spinach pyruvate kinase isoforms: partial purification and regulatory properties

Journal Article · Wed Feb 01 04:00:00 EST 1984 · Plant Physiol.; (United States)

DOI:https://doi.org/10.1104/pp.74.2.374· OSTI ID:6584210

Baysdorfer, C; Bassham, J A

Pyruvate kinase from spinach (Spinacea oleracea L.) leaves consists of two isoforms, separable by blue agarose chromatography. Both isoforms share similar pH profiles and substrate and alternate nucleotide K/sub m/ values. In addition, both isoforms are inhibited by oxalate and ATP and activated by AMP. The isoforms differ in their response to three key metabolites; citrate, aspartate, and glutamate. The first isoform is similar to previously reported plant pyruvate kinases in its sensitivity to citrate inhibition. The K/sub i/ for this inhibition is 1.2 millimolar citrate. The second isoform is not affected by citrate but is regulated by aspartate and glutamate. Aspartate is an activator with a K/sub a/ of 0.05 millimolar, and glutamate is an inhibitor with a K/sub i/ of 0.68 millimolar. A pyruvate kinase with these properties has not been previously reported. Based on these considerations, the authors suggest that the activity of the first isoform is regulated by respiratory metabolism. The second isoform, in contrast, may be regulated by the demand for carbon skeletons for use in ammonia assimilation.

• Research Organization: Lawrence Berkeley Lab., CA
• DOE Contract Number: AC03-76SF00098
• OSTI ID: 6584210
• Journal Information: Plant Physiol.; (United States), Journal Name: Plant Physiol.; (United States) Vol. 74:2; ISSN PLPHA
• Country of Publication: United States
• Language: English

Related Subjects

550200* -- Biochemistry
59 BASIC BIOLOGICAL SCIENCES
AMIDES
AMINO ACIDS
AMP
ATP
CARBOXYLIC ACID SALTS
CARBOXYLIC ACIDS
CHEMICAL ACTIVATION
CHEMICAL PROPERTIES
CITRATES
ENZYME ACTIVITY
ENZYMES
FOOD
GLUTAMINE
INHIBITION
LEAVES
NUCLEOTIDES
ORGANIC ACIDS
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
OXALATES
PHOSPHORUS-GROUP TRANSFERASES
PHOSPHOTRANSFERASES
PLANTS
SPINACH
TRANSFERASES
VEGETABLES