Inhibitive effect of zinc ion on fatty acid synthase from chicken liver.
Fatty acid synthase (FAS; acyl-CoA:malonyl-CoA C-acyltransferase [decarboxylating, oxoacyl- and enoyl-reducing and thioester-hydrolyzing], EC 2.3.1.85) is an important enzyme participating in energy metabolism in vivo which is related to adiposis and cancer [Cancer Lett. 167 (1) (2001) 99; Nat. Med. 8 (4) (2002) 335]. Tests of fast- and slow-binding inhibitions showed that fatty acid synthase of chicken liver is rapidly and irreversibly inactivated by low Zn(2+) concentrations. Electrophoresis and FPLC results showed that FAS cross-links occurred in the presence of high Zn(2+) concentrations (>4 microM) which may be another reason that FAS lost its activity. The modification velocity of FAS by DTNB decreased with increasing Zn(2+) concentration, which confirmed that Zn(2+) interacted with SH groups. Substrate protective experiments and sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) showed that all three substrates tested had some protective effects on FAS in the presence of Zn(2+), and malonyl-CoA was the most effective of the three substrates. In the presence of malonyl-CoA, the activity loss of FAS decreased sharply and almost no cross-link was observed in SDS-PAGE. This suggests that the phosphopantetheine SH group is the critical group in the cross-link and inhibition of FAS in the presence of Zn(2+).
Wang
Fan
F
Department of Biological Sciences and Biotechnology, University of Tsinghua, Beijing 100084, PR China.
Wang
Xuan
X
Liu
Yu
Y
Tian
Wei-Xi
WX
Zhou
Hai-Meng
HM
D000818:Animals; D001667:Binding, Competitive; D002645:Chickens; D002845:Chromatography; D002853:Chromatography, Liquid; D003432:Cross-Linking Reagents / Q000494:pharmacology; D004591:Electrophoresis, Polyacrylamide Gel; D064429:Fatty Acid Synthases / Q000737:chemistry / Q000494:pharmacology*; D007477:Ions; D008099:Liver / Q000187:drug effects / Q000378:metabolism*; D008316:Malonyl Coenzyme A / Q000378:metabolism; D013997:Time Factors; D015032:Zinc / Q000378:metabolism / Q000494:pharmacology*
D003432:Cross-Linking Reagents; D007477:Ions; D008316:Malonyl Coenzyme A; D064429:Fatty Acid Synthases; D015032:Zinc