二氢叶酸还原酶（dihydrofolate reductase，DHFR）
催化反应1
[[0. 维生素B9：叶酸（FA，folate）]]+NADPH+^+$->[[二氢叶酸（DHF）]]+^+$
\usepackage{chemfig}
\begin{document}
\chemfig{
N=[7,0.8](-[6,0.6]NH_2)-[,0.8]N(-[0,0.3]H)-[1,0.8](=[,0.6]O)-[3,0.8]
(-[1,0.8]N=[3,0.8]
(-[2,0.6]CH_2-[2,0.6]
NH-[2,0.6]**6(
-
-
-(-[,0.6]C
(=[4,0.7]O)
(-[2,0.7]
NH-[2,0.6]CH
(-[4,0.6]HOOC)
(-[2,0.6]CH_2
(-[2,0.6]CH_2
(-[2,0.6]COOH)
)
)
)
)
-
-
-
)
)
-[4,0.8]=[5,0.8]N-[7,0.8])
=[4,0.8]-[5,0.6]
}
+NADPH+^+$
\begin{tikzpicture}
\draw [->] (0,0) to node[above] {DHFR} (1,0);
\end{tikzpicture}
\chemfig{
N(-[4,0.3]H)-[7,0.8](-[6,0.6]NH_2)=[,0.8]N-[1,0.8](=[,0.6]O)-[3,0.8]
(-[1,0.8]N=[3,0.8]
(-[2,0.6]CH_2-[2,0.6]
NH-[2,0.6]**6(
-
-
-(-[,0.6]C
(=[4,0.7]O)
(-[2,0.7]
NH-[2,0.6]CH
(-[4,0.6]HOOC)
(-[2,0.6]CH_2
(-[2,0.6]CH_2
(-[2,0.6]COOH)
)
)
)
)
-
-
-
)
)
-[4,0.8]-[5,0.8]N(-[4,0.3]H)-[7,0.8])
=[4,0.8]-[5,0.6]
}
+^+$
\end{document}催化反应2 [[二氢叶酸（DHF）]]+NADPH+^+$->[[四氢叶酸（THF）]]+^+$
\usepackage{chemfig}
\begin{document}
\chemfig{
N(-[4,0.3]H)-[7,0.8](-[6,0.6]NH_2)=[,0.8]N-[1,0.8](=[,0.6]O)-[3,0.8]
(-[1,0.8]N=[3,0.8]
(-[2,0.6]CH_2-[2,0.6]
NH-[2,0.6]**6(
-
-
-(-[,0.6]C
(=[4,0.7]O)
(-[2,0.7]
NH-[2,0.6]CH
(-[4,0.6]HOOC)
(-[2,0.6]CH_2
(-[2,0.6]CH_2
(-[2,0.6]COOH)
)
)
)
)
-
-
-
)
)
-[4,0.8]-[5,0.8]N(-[4,0.3]H)-[7,0.8])
=[4,0.8]-[5,0.6]
}
+NADPH+^+$
\begin{tikzpicture}
\draw [->] (0,0) to node[above] {DHFR} (1,0);
\end{tikzpicture}
\chemfig{
N(-[4,0.3]H)-[7,0.8](-[6,0.6]NH_2)=[,0.8]N-[1,0.8](=[,0.6]O)-[3,0.8]
(-[1,0.8]N(-[,0.3]H)(-[4,0.3]5)-[3,0.8]
(-[2,0.6]CH_2-[2,0.6]
NH(-[4,0.3]10)-[2,0.6]**6(
-
-
-(-[,0.6]C
(=[4,0.7]O)
(-[2,0.7]
NH-[2,0.6]CH
(-[4,0.6]HOOC)
(-[2,0.6]CH_2
(-[2,0.6]CH_2
(-[2,0.6]COOH)
)
)
)
)
-
-
-
)
)
-[4,0.8]-[5,0.8]N(-[4,0.3]H)-[7,0.8])
=[4,0.8]-[5,0.6]
}
+^+$
\end{document}[[甲氧苄啶（trimethoprim）]]为抑制剂