Regulation of the glycine cleavage system in rat liver

Thesis/Dissertation · Sun Jan 01 04:00:00 EST 1984

OSTI ID:6108188

Hampson, R K

Catabolism of glycine, via the glycine cleavage system was investigated in isolated, fully functional, rat liver mitochondria, and the isolated perfused rat liver. Metabolic flux through the glycine cleavage system, which catalyzes the tetrahydrofolate-dependent cleavage of glycine yielding carbon dioxide, ammonia, N/sup 5/,N/sup 10/-methylenetetrahydrofolate, and NADH + H/sup +/, was monitored by measuring the production of /sup 14/CO/sub 2/ from (1-/sup 14/C)glycine. The glycine cleavage system was demonstrated to be responsible for nearly all /sup 14/CO/sub 2/ production from (1-/sup 14/C)glycine in both isolated mitochondria and the perfused rat liver. Glycine decarboxylation by rat liver mitochondria was highly sensitive to the metabolic state in which the mitochondria were maintained. Production of /sup 14/CO/sub 2/ from (1-/sup 14/C)glycine was stimulated in State 3 over State 4 and was maximal in the uncoupled state. Alternatively, respiratory inhibitors, such as rotenone, and reducing substrates, inhibited mitochondrial glycine decarboxylation strongly. Propionate stimulated glycine decarboxylation by rat liver mitochondria with a concomitant decrease in the measured intramitochondrial NADPH content. Incubation of mitochondria with propionate evoked a large decrease in the measured intramitochondrial ATP content and a large increase in AMP content. Manipulation of the intramitochondrial adenine nucleotide profile demonstrated that no direct correlation existed between rates of mitochondrial glycine decarboxylation and the intramitochondrial content of either ATP, ADP, or AMP.

• Research Organization: Texas Univ., San Antonio (USA). Health Science Center
• OSTI ID: 6108188
• Country of Publication: United States
• Language: English

Related Subjects

550501* -- Metabolism-- Tracer Techniques
59 BASIC BIOLOGICAL SCIENCES
ADP
AMINO ACIDS
AMP
ANIMALS
ATP
BODY
CARBON 14 COMPOUNDS
CARBON COMPOUNDS
CARBON DIOXIDE
CARBON OXIDES
CARBOXYLIC ACIDS
CELL CONSTITUENTS
CHALCOGENIDES
CHEMICAL REACTIONS
CLEAVAGE
COENZYMES
CRYSTAL STRUCTURE
DECARBOXYLATION
DIGESTIVE SYSTEM
GLANDS
GLYCINE
ISOTOPE APPLICATIONS
LABELLED COMPOUNDS
LIVER
MAMMALS
METABOLISM
MICROSTRUCTURE
MITOCHONDRIA
NADP
NUCLEOTIDES
ORGANIC ACIDS
ORGANIC COMPOUNDS
ORGANOIDS
ORGANS
OXIDES
OXYGEN COMPOUNDS
PERFUSED ORGANS
RATS
RODENTS
TRACER TECHNIQUES
VERTEBRATES