The objective of the proposed studies is to characterize the function, regulation and consequences of the inhibition of key mitochondrial enzymes in order to understand the effect of these enzymes and their inhibition on the metabolism of the cell and their involvement in the toxicology of environmental chemicals. As well as providing basic information on the nature and properties of the enzymes to be studied, the health-related aims of the proposed experiments are: (1) to elucidate factors affecting the transfer of fatty acids which are an important fuel source, especially in liver and heart. A new view of the role of peroxisomal carnitine palmitoyltransferase in fatty acid metabolism will also be investigated; (2) to investigate the intracellular biochemical events which lead to the onset of Parkinson's disease, a sequence which involves monamine oxidase, an energy-dependent mitochondrial uptake process, and inhibition of the respiratory enzyme, NADH-Q oxidoreductase; (3) to identify potential environmental toxins which may be responsible for the onset of Parkinson's disease using the relatively simple in vitro systems listed above; (4) to survey these same toxins as substrates and inhibitors of monoamine oxidase, because inhibition of either the A or B forms (which have different specificities) can seriously disturb amine metabolism both in the brain and in peripheral tissues. Biochemically, the mechanisms, function and structure of the enzyme systems involved will be studied in intact mitochondria from normal and diseased tissues, in membrane fragments and isolated enzymes, using inhibitors and alternate substrates to examine regulation and malfunction. Studies on monoamine oxidase will continue using steady-state and pre-steady state kinetics to study the mechanism(s) of the two forms of the enzyme and their specificities with pyridine derivatives to correlate with or predict in vivo toxicity of such compounds. The toxicity of pyridinium compounds to mitochondrial respiration, which leads to cell death, will be explored. Their chemical versatility presents a unique opportunity to study the Q-binding site of NADH-Q oxidoreductase and to characterize the mitochondrial cation accumulation system, both of which are implicated in the onset of acute Parkinsonism.

Agency
National Institute of Health (NIH)
Institute
National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK)
Type
Research Project (R01)
Project #
5R01DK041572-03
Application #
3242386
Study Section
Neurological Sciences Subcommittee 1 (NLS)
Project Start
1989-05-20
Project End
1992-04-30
Budget Start
1991-09-25
Budget End
1992-04-30
Support Year
3
Fiscal Year
1991
Total Cost
Indirect Cost
Name
University of California San Francisco
Department
Type
Schools of Medicine
DUNS #
073133571
City
San Francisco
State
CA
Country
United States
Zip Code
94143
Ramsay, R R; Gandour, R D (1999) Selective modulation of carnitine long-chain acyltransferase activities. Kinetics, inhibitors, and active sites of COT and CPT-II. Adv Exp Med Biol 466:103-9
Nic a'Bhaird, N; Yankovskaya, V; Ramsay, R R (1998) Active sites residues of beef liver carnitine octanoyltransferase (COT) and carnitine palmitoyltransferase (CPT-II). Biochem J 330 ( Pt 2):1029-36
Cronin, C N (1997) cDNA cloning, recombinant expression, and site-directed mutagenesis of bovine liver carnitine octanoyltransferase--Arg505 binds the carboxylate group of carnitine. Eur J Biochem 247:1029-37
Nic a'Bhaird, N; Ramsay, R R (1995) The active site histidine of carnitine acyltransferases. Biochem Soc Trans 23:490S
Ramsay, R R (1994) Carnitine and its role in acyl group metabolism. Essays Biochem 28:47-61
Ramsay, R R; Arduini, A (1993) The carnitine acyltransferases and their role in modulating acyl-CoA pools. Arch Biochem Biophys 302:307-14
Gandour, R D; Leung, O T; Greway, A T et al. (1993) (+)-Hemipalmitoylcarnitinium strongly inhibits carnitine palmitoyltransferase-I in intact mitochondria. J Med Chem 36:237-42
Brady, P S; Ramsay, R R; Brady, L J (1993) Regulation of the long-chain carnitine acyltransferases. FASEB J 7:1039-44
Nic a' Bhaird, N; Kumaravel, G; Gandour, R D et al. (1993) Comparison of the active sites of the purified carnitine acyltransferases from peroxisomes and mitochondria by using a reaction-intermediate analogue. Biochem J 294 ( Pt 3):645-51
Reznick, A Z; Kagan, V E; Ramsey, R et al. (1992) Antiradical effects in L-propionyl carnitine protection of the heart against ischemia-reperfusion injury: the possible role of iron chelation. Arch Biochem Biophys 296:394-401

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