Stimulation of bovine heart pyruvate dehydrogenase kinase by. cap alpha. -ketoisovalerate in the presence of thiamin pyrophosphate

Conference · Fri May 01 04:00:00 EDT 1987 · Fed. Proc., Fed. Am. Soc. Exp. Biol.; (United States)

OSTI ID:6179651

Robertson, J G; Barron, L L; Olson, M S

Purified bovine heart pyruvate dehydrogenase complex was used to study pyruvate dehydrogenase kinase (PDH kinase) regulation. Previously, they showed that KCl and NH4Cl stimulate PDH kinase, and that thiamin pyrophosphate over the range of 1-80 ..mu..M completely blocks PDH kinase stimulation by 20 mM KCl, whereas thiamin pyrophosphate has very little inhibitory effect in the absence of KCl. Under inhibitory conditions, 100 ..mu..M thiamin pyrophosphate and 20 mM KCl, addition of 1 mM ..cap alpha..-ketoisovalerate stimulated PDH kinase activity 1.5-fold. Addition of 1 mM ..cap alpha..-ketoisovalerate had a similar stimulatory effect in the presence of 1 mM NH4Cl and 100 ..mu..M thiamin pyrophosphate. Half-maximal stimulation occurred at about 200 ..mu..M ..cap alpha..-ketoisovalerate in both cases. Inhibition by thiamin pyrophosphate was uncompetitive, and the effect of ..cap alpha..-ketoisovalerate on thiamin pyrophosphate inhibition was to shift both Vm and Km toward control values without changing the slope of the reciprocal plot. After incubation of pyruvate dehydrogenase complex with ..cap alpha..-ketoisovalerate and gel filtration on Sephadex G-25 to remove ..cap alpha..-ketoisovalerate, PDH kinase activity remained stimulated relative to controls incubated with only buffer. In bovine heart mitochondria solubilized in 0.2% Triton X-100 and incubated with (..gamma..-/sup 32/P)ATP, ..cap alpha..-ketoisovalerate stimulated PDH phosphorylation in the presence of thiamin pyrophosphate, as detected by SDS-PAGE and autoradiography. The results indicate that acylation of pyruvate dehydrogenase complex results in PDH kinase stimulation, but only in the presence of monovalent cation and thiamin pyrophosphate. Furthermore, the results also suggest that this effect may be relevant under more in vivo conditions.

• Research Organization: Univ. of Texas Health Science Center, San Antonio
• OSTI ID: 6179651
• Report Number(s): CONF-870644-
• Conference Information: Journal Name: Fed. Proc., Fed. Am. Soc. Exp. Biol.; (United States) Journal Volume: 46:6
• Country of Publication: United States
• Language: English

Related Subjects

550201* -- Biochemistry-- Tracer Techniques
59 BASIC BIOLOGICAL SCIENCES
ANIMALS
ATP
BETA DECAY RADIOISOTOPES
BETA-MINUS DECAY RADIOISOTOPES
BIOCHEMICAL REACTION KINETICS
BODY
CARBOXYLIC ACIDS
CARDIOVASCULAR SYSTEM
CATTLE
DAYS LIVING RADIOISOTOPES
DOMESTIC ANIMALS
ENZYME ACTIVITY
ENZYMES
HEART
ISOTOPE APPLICATIONS
ISOTOPES
ISOVALERIC ACID
KINETICS
LIGHT NUCLEI
MAMMALS
MONOCARBOXYLIC ACIDS
NUCLEI
NUCLEOTIDES
ODD-ODD NUCLEI
ORGANIC ACIDS
ORGANIC COMPOUNDS
ORGANS
OXIDOREDUCTASES
OXYGEN COMPOUNDS
PHOSPHORUS 32
PHOSPHORUS COMPOUNDS
PHOSPHORUS ISOTOPES
PHOSPHORUS-GROUP TRANSFERASES
PHOSPHOTRANSFERASES
PYROPHOSPHATES
RADIOISOTOPES
REACTION KINETICS
RUMINANTS
TRACER TECHNIQUES
TRANSFERASES
VERTEBRATES