第3次脱氢
称谓
琥珀酸脱氢酶 复合体II 琥珀酸-Q还原酶 琥珀酸-Q氧化还原酶 Butane diacid succinate dehydrogenase SDH
特点
是含铁-硫中心的黄素蛋白 只脱氢，不脱羧
生理作用
• FAD接受氢，进入FAD呼吸链。
催化反应
[[C4：琥珀酸（succinic）]]+[[FAD]]<-->[[C4：延胡索酸（富马酸，fumaric）]]+[[FADH2]]
$化学方程式：$
-
\usepackage{chemfig}
\begin{document}
\chemfig{
CH_2
(-[2,0.5]CH_2-[,0.5]COO^{-})
(-[,0.5]COO^{-})
}
+$
\begin{tikzpicture}
\draw [<->] (0,0) to node[above] {SDH} (1,0); % 水平箭头
\end{tikzpicture}
\chemfig{
CH
(=[2,0.5]CH-[,0.5]COO^{-})
(-[,0.5]COO^{-})
}
+$
+1.5ATP
\end{document}-
\usepackage{chemfig}
\begin{document}
\chemfig{
CH_2
(-[2,0.5]CH_2-[,0.5]COOH)
(-[,0.5]COOH)
}
+$
\begin{tikzpicture}
\draw [<->] (0,0) to node[above] {SDH} (1,0); % 水平箭头
\end{tikzpicture}
\chemfig{
CH
(=[2,0.5]CH-[,0.5]COOH)
(-[,0.5]COOH)
}
+$
+1.5ATP
\end{document}-
\usepackage{chemfig}
\begin{document}
\chemfig{
(-[3.5,0.5]HO)
(=[6,0.5]O)
(-[0.5,0.5]
(-[7.5,0.5]
(-[0.5,0.5]
(=[2,0.5]O)
(-[7.5,0.5]OH)
)
)
)
}
+$
\begin{tikzpicture}
\draw [<->] (0,0) to node[above] {SDH} (1,0); % 水平箭头
\end{tikzpicture}
\chemfig{
(-[3.5,0.5]HO)
(=[6,0.5]O)
(-[0.5,0.5]
(=[7.5,0.5]
(-[0.5,0.5]
(=[2,0.5]O)
(-[7.5,0.5]OH)
)
)
)
}
+$
+1.5ATP
\end{document}-
OC(CCC(O)=O)=O>>
OC(=O)C=CC(=O)O后续反应
$被释放到[[线粒体基质（mitochondrial matrix）]]中：
\usepackage{chemfig}
\begin{document}
\chemfig{
FADH_2
}
+Q
\begin{tikzpicture}
\draw [->] (0,0) to node[above] {} (1,0); % 水平箭头
\end{tikzpicture}
\chemfig{
FAD
}
+\chemfig{
QH_2
}
\end{document}FAD自动又回来了。
总反应
[[C4：琥珀酸（succinic）]]+[[0. 维生素Q：辅酶Q（泛醌，ubiquinone）]]<-->[[C4：延胡索酸（富马酸，fumaric）]]+[[还原型辅酶Q（UQH2）]]
$化学方程式：$
-
\usepackage{chemfig}
\begin{document}
\chemfig{
CH_2
(-[2,0.5]CH_2-[,0.5]COOH)
(-[,0.5]COOH)
}
+$
+$
\begin{tikzpicture}
\draw [<->] (0,0) to node[above] {SDH} (1,0); % 水平箭头
\end{tikzpicture}
\chemfig{
CH
(=[2,0.5]CH-[,0.5]COOH)
(-[,0.5]COOH)
}
+\chemfig{
FADH_2
}
+$
\end{document}-
\usepackage{chemfig}
\begin{document}
\chemfig{
(-[3.5,0.5]HO)
(=[6,0.5]O)
(-[0.5,0.5]
(-[7.5,0.5]
(-[0.5,0.5]
(=[2,0.5]O)
(-[7.5,0.5]OH)
)
)
)
}
+FAD
+$
\begin{tikzpicture}
\draw [<->] (0,0) to node[above] {SDH} (1,0); % 水平箭头
\end{tikzpicture}
\chemfig{
(-[3.5,0.5]HO)
(=[6,0.5]O)
(-[0.5,0.5]
(=[7.5,0.5]
(-[0.5,0.5]
(=[2,0.5]O)
(-[7.5,0.5]OH)
)
)
)
}
+\chemfig{
FADH_2
}
+$
\end{document}机理
![[Complex_II.png]]
下一步
[[7. TAC：延胡索酸水合为苹果酸：延胡索酸酶（fumarase）]]