Dual role of free fatty acids in regulation of mitochondrial L-glycerol-3-phosphate dehydrogenase.

In brown adipose tissue mitochondria, the influence of free fatty acids on FAD-linked L-glycerol-3-phosphate dehydrogenase was investigated using either hydrophilic or hydrophobic electron acceptors. The apparent kinetic parameters were determined for substrate and electron acceptors in the presence of different concentrations of oleic acid. In contrast to the L-glycerol-3-phosphate dehydrogenase enzyme from mitochondrial hyperthyroid rat liver, the brown adipose tissue enzyme shows only a single detectable L-glycerol-3-phosphate binding site.

Substrate binding properties of L-glycerol-3-phosphate dehydrogenase in isolated liver mitochondria of hyperthyroid rats.

In isolated, intact liver mitochondria from hyperthyroid rats, the L-glycerol-3-phosphate binding site(s) of the L-glycerol-3-phosphate dehydrogenase was (were) found to be influenced by the nature of the electron acceptor, as well as by the pH and the presence of calcium ions. With the hydrophobic electron acceptor menadione a single L-glycerol-3-phosphate binding site was detected kinetically at bulk pH values between 6.5 and 9.

Incorporation of mitochondrial L-glycerol-3-phosphate dehydrogenase into liposomes; effect of sodium oleate and calcium ions.

FAD-linked L-glycerol-3-phosphate dehydrogenase purified from liver mitochondria of hyperthyroid rats was incorporated into unilamellar phospholipid liposomes. The incorporation influenced both Vmax,app and Km,app values of the enzyme for its substrate, L-glycerol 3-phosphate. The Km,app for the electron acceptor remained unchanged with a simultaneous slight enhancement of the corresponding Vmax,app value.

Role of cardiolipin in the functioning of mitochondrial L-glycerol-3-phosphate dehydrogenase.

Adriamycin was used in situ, in isolated liver mitochondria of hyperthyroid rats to study the role of cardiolipin in the functioning of FAD-linked L-glycerol-3-phosphate dehydrogenase. The apparent kinetic parameters of the reaction catalyzed by the enzyme were affected by adriamycin. The effect of adriamycin was dependent on the electron acceptor, suggesting the existence of distinct binding sites for hydrophobic and hydrophilic acceptors.

Influence of thyroid status on the membranes of rat liver mitochondria. Unique localization of L-glycerol-3-phosphate dehydrogenase.

The effect of thyroid status on the physical properties of rat liver mitochondrial membranes and on the lipid microenvironment of proteins was investigated. The steady-state fluorescence anisotropy of diphenyl-1,3,5-triene and 1-[4-(trimethylaminophenyl)phenyl]-6-phenylhexa-1,3,5-triene revealed an increase of the order of the membranes with the increase of hormone level. Protein arrangement in the inner mitochondrial membrane altered with the thyroid status, which was reflected by digitonin subfractionation of mitochondria.

Effect of chemical modification in situ on L-glycerol-3-phosphate dehydrogenase in brown adipose tissue mitochondria.

Mitochondrial L-glycerol-3-phosphate dehydrogenase (E.C. 1.

Ca2+ and Mg2+ as modulators of mitochondrial L-glycerol-3-phosphate dehydrogenase.

1. Physiological concentrations of either Ca2+ or Mg2+ stimulated L-glycerol 3-phosphate oxidation by intact mitochondria isolated from various mammalian tissues (hamster brown adipose tissue, rat brain, liver of normal and hyperthyroid rats). A higher cation concentration was required for stimulation by Mg2+ than by Ca2+.

Purification of L-3-glycerophosphate dehydrogenase from rat liver mitochondria.

A rapid three-step procedure is presented for the purification of flavin-linked L-3-glycerophosphate dehydrogenase (E.C. 1.