关键词: 脂肪酸合酶, 酮酰还原酶, 红茶, 茶黄素, 抑制剂

Abstract:

Inhibitory activity and character of black tea extract and theaflavins are measured through inhibition kinetics.Based on the kinetics data,both of them are proved to be effective inhibitors of β-ketoacyl reductase of type I fatty acid synthase (KR),which exists in animals and β-ketoacyl reductase of type II fatty acid synthase (FabG),which exists in bacteria.The two inhibitors exhibit potent reversible and irreversible inhibitory activity on KR and FabG and are competitive inhibitors against NADPH,which is one of substrates of KR and FabG.The presence of NADPH clearly prevents the inactivation of KR and FabG by those two inhibitors.This shows that the inhibitors might act on NADPH binding site of KR and FabG.The consistent inhibitory character of two inhibitors suggests that these two β-ketoacyl reductases with different evaluation degrees possess similar active sites.The homology analysis of amino acid sequence shows that there exists one highly homologous region which may be responsible for the formation of active site located in KR and FabG.Therefore,the conformation of the active site in KR can be understood through the study of FabG.These two inhibitors are promising for practical application because of their potent inhibitory activity and rich sources.

Key words: fatty acid synthase, β, -ketoacyl reductase, black tea, theaflavins, inhibitor