scholarly journals The mechanism of the inhibition of the mitochondrial pyruvate transportater by α-cyanocinnamate derivatives

1976 ◽  
Vol 156 (1) ◽  
pp. 181-183 ◽  
Author(s):  
A P Halestrap

Pyruvate transport into rat liver mitochondria is inhibited by a variety of thiol reagents. alpha-Cyanocinnamate and its derivates, potent and reversible inhibitors of pyruvate transport, react reversibly with mercaptoethanol and cysteine to form addition products. It is concluded that these inhibitors react with an essential thiol group on the pyruvate carrier.

1983 ◽  
Vol 214 (3) ◽  
pp. 1027-1030 ◽  
Author(s):  
V A Zammit

Preincubation of rat liver mitochondria with 5,5′-dithiobis-(2-nitrobenzoic acid) (Nbs2) followed by removal of excess reagent by washing the mitochondria with 0.5 mM-reduced glutathione resulted in a desensitization of carnitine palmitoyltransferase (CPT) I activity to malonyl-CoA inhibition. The effect was not observed if mitochondria were washed with 0.5 mM-dithiothreitol. The desensitization effect of Nbs2 could be reversed by a second incubation in the presence of 8 microM-malonyl-CoA. In addition, malonyl-CoA, when present simultaneously with Nbs2, protected CPT I activity against the desensitization effect of the thiol-group reagent. These results suggest that malonyl-CoA exerts an effect on one or more thiol groups of the enzyme, and that this effect is related to the ability of the metabolite to sensitize CPT I to malonyl-CoA inhibition.


Author(s):  
E. A. Elfont ◽  
R. B. Tobin ◽  
D. G. Colton ◽  
M. A. Mehlman

Summary5,-5'-diphenyl-2-thiohydantoin (DPTH) is an effective inhibitor of thyroxine (T4) stimulation of α-glycerophosphate dehydrogenase in rat liver mitochondria. Because this finding indicated a possible tool for future study of the mode of action of thyroxine, the ultrastructural and biochemical effects of DPTH and/or thyroxine on rat liver mere investigated.Rats were fed either standard or DPTH (0.06%) diet for 30 days before T4 (250 ug/kg/day) was injected. Injection of T4 occurred daily for 10 days prior to sacrifice. After removal of the liver and kidneys, part of the tissue was frozen at -50°C for later biocheailcal analyses, while the rest was prefixed in buffered 3.5X glutaraldehyde (390 mOs) and post-fixed in buffered 1Z OsO4 (376 mOs). Tissues were embedded in Araldlte 502 and the sections examined in a Zeiss EM 9S.Hepatocytes from hyperthyroid rats (Fig. 2) demonstrated enlarged and more numerous mitochondria than those of controls (Fig. 1). Glycogen was almost totally absent from the cytoplasm of the T4-treated rats.


Author(s):  
Olga A. Gonchar ◽  
Valentina I. Nosar ◽  
Larisa. V. Bratus ◽  
I. N. Tymchenko ◽  
N. N. Steshenko ◽  
...  

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