Tissue specific alterations in the El. cap alpha. subunit of branched-chain ketoacid dehydrogenase (BCKD) in rats
Polyclonal antibodies (anti-E1E2 IgG) directed against bovine kidney BCKD have been used to examine the metabolic role of this enzyme in the rat. BCKD activity was assayed in detergent-disrupted kidney mitochondria using (1-/sup 14/C)..cap alpha..-ketoacids. Rates of oxidation of the keto analogs of leucine, valine and isoleucine were 21.6 +/- 1.5, 20.6 +/- 1.3 and 10.2 +/- 0.6 nmol/min/mg protein, respectively. Addition of anti-E1E2 IgG completely inhibited oxidation of all 3 ketoacids. Anti-E1E2 IgG inhibited oxidation of the keto analogs derived from methionine and threonine by 75% and 30%, respectively. It did not inhibit mitochondrial dehydrogenases other than BCKD. Thus, BCKD appears to be important in oxidative metabolism of 5 of the 9 indispensable amino acids. Immunoblots of rat kidneys, liver, muscle and heart mitochondria revealed a tissue specific alteration in the E1..cap alpha.. subunit of BCKD. Kidneys and heart each appeared to contain two E1..cap alpha.. polypeptides differing by an apparent molecular weight of 900 daltons; the predominant E1..cap alpha.. polypeptide in heart was the heavier E1..cap alpha.. band whereas in kidney it was the lighter band. Liver and muscle, however, each exhibited a single but different E1..cap alpha.. polypeptide. E1..cap alpha.. in liver corresponded to the lighter E1..cap alpha.. polypeptide of kidney and heart whereas in muscle E1..cap alpha.. corresponded to the heavier polypeptide. The E1..cap alpha.. subunit differences are associated with differences in basal BCKD activity of these tissues.
- Research Organization:
- Univ. of Wisconsin, Madison
- OSTI ID:
- 5435936
- Report Number(s):
- CONF-8604222-; TRN: 86-026634
- Journal Information:
- Fed. Proc., Fed. Am. Soc. Exp. Biol.; (United States), Vol. 45:3; Conference: 70. annual meeting of the Federation of American Society for Experimental Biology, St. Louis, MO, USA, 13 Apr 1986
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
LEUCINE
METABOLISM
OXIDOREDUCTASES
ENZYME ACTIVITY
VALINE
ANTIBODIES
CARBON 14 COMPOUNDS
CATTLE
HEART
KIDNEYS
LIVER
MITOCHONDRIA
MOLECULAR WEIGHT
MUSCLES
POLYPEPTIDES
TRACER TECHNIQUES
AMINO ACIDS
ANIMALS
BODY
CARBOXYLIC ACIDS
CARDIOVASCULAR SYSTEM
CELL CONSTITUENTS
DIGESTIVE SYSTEM
DOMESTIC ANIMALS
ENZYMES
GLANDS
ISOTOPE APPLICATIONS
LABELLED COMPOUNDS
MAMMALS
ORGANIC ACIDS
ORGANIC COMPOUNDS
ORGANOIDS
ORGANS
PEPTIDES
PROTEINS
RUMINANTS
VERTEBRATES
550201* - Biochemistry- Tracer Techniques