Oxidation of Long Chain Fatty Acids by Rat Liver Mitochondria

Abstract Long chain fatty acids are oxidized by rat liver mitochondria provided that endogenous adenosine triphosphate is not depleted. If endogenous ATP is depleted, e.g. by 2,4-dinitrophenol, external ATP as well as carnitine is required for fatty acid oxidation. Atractyloside does not block this reaction in media containing orthophosphate buffer. Oligomycin can substitute for carnitine, but the oligomycin-dependent route is inhibited by atractyloside. These experimental situations localize two ATP-dependent fatty acid-activating systems, one of which is linked to carnitine. The dinitrophenol-insensitive, GTP-specific fatty acyl coenzyme A synthetase is active only in the absence of orthophosphate. Inhibition of oxidation of fatty acids by atractylate in phosphate-free media is not relieved with oligomycin or carnitine

A Guanosine Triphosphate-dependent Acyl Coenzyme A Synthetase from Rat Liver Mitochondria

A guanosine triphosphate-specific acyl coenzyme A synthetase has been purified from extracts of sonically disrupted rat liver mitochondria. This enzyme, which is free of adenosine triphosphate-dependent activating systems and from succinyl-CoA synthetase activity, catalyzes the formation of CoA esters of both long and short chain fatty acids. GTP-specific fatty acid activation is inhibited by orthophosphate and fluoride

Dipole Moment of Acetylcholine and Its Relevance to the Chemical Synaptic Transmission

The dipole moment of acetylcholine (AcCh) has been measured in chloroform and a value of 8.49 D was obtained. Such a value actually represents the total dipole moment of the ion pair (AcCh)(+)(Cl)(-). The dipole moment of the (AcCh)(+) cation alone turned out to be 2.65 D whereas its theoretical value obtained after a vectorial calculation was 1.65 D. The discrepancy was related to an interaction between AcCh and the solvent. The meaning of the measured value is discussed on the basis of a recent theory of chemical synaptic transmission based on the assumption of a much higher dipole moment value for the AcCh molecule

Pharmacokinetics of fructose-1, 6-diphosphate in the rat.

The pharmacokinetics of fructose-1, 6-diphosphate administered to the rat by intravenous injection was studied. Labelled fructose-1, 6-diphosphate was measured in blood, where it reaches the highest amount 10 min after administration, and in different organs. Residual radioactivity was measured in organs 20 min after administration, the highest values being found in the kidney and the lowest in the brain. The hydrolytic activity of the various organs toward fructose-1, 6-diphosphate was measured in organ extracts and was found to be maximal in the kidney and minimal in the brain

CHIMICA con cenni di mineralogia e di chimica biologica

Manuale di CHIMICA per Licei ed Istituti Magistral

CORSO DI CHIMICA, con cenni di chimica biologica

MANUALE DI CHIMICA, con cenni di chimica biologica, per Istituti Tecnici Commercial

Production of reduced forms of oxygen by adrenochrome in the presence of ascorbate, microsomes and submitochondrial particles.

Adrenochrome, an oxidation product of adrenaline with psychotomimetic properties, can be reduced by ascorbate in a reaction that shows a rapid oxygen consumption. Superoxide dismutase and catalase strongly inhibit this oxygen uptake. Similarly the addition of adrenochrome to rat liver microsomes or beef heart submitochondrial particles supplemented with reduced substrates determine a large consumption of oxygen. The reported results are compatible with a redox cycle where reducing equivalents supplied by ascorbate or the electron transport chains of microsomes or mitochondria are able to reduce adrenochromewhich subsequently reoxidized by oxygen with the reproduction of superoxide anion and hydrogen peroxide

TOXICITY OF AMINOCHROMES

The first part of the present review deals with the chemical and enzymatic synthesis of adrenochrome and other aminochromes from the corresponding catecholamines. A description of the most significant pathways of formation and the reactivity of the aminochromes is presented. In the second part of the toxicity of aminochromes, mainly at the cardiac and CNS level, is described and some of the molecular mechanisms of the toxic action are outlined. The toxicity of the aminochromes appears to depend mainly on the production of reduced oxygen species through redox cycling. The interaction of aminochromes with sulfhydryl groups and the induced depletion of oxygen, ascorbate and glutathione are additional mechanisms resulting in noxious effects at a cellular level