N1的形成：合成酶（PAICS(E2)）

[[5-氨基-4-羧基咪唑核苷酸（CAIR）]]+[[C4：天冬氨酸（Asp，aspartate）]]+ATP<->[[N-琥珀酰-5-氨基-4-羧基咪唑核苷酸（SACAIR）]]+ADP+$

\usepackage{chemfig}
\begin{document}

\chemfig{
	\fbox{R}-[2,0.8]N(-[2,0.25]9)
	-[3.5,0.6](-[3.3,0.25]4)(-[4.5,0.7]N(-[2,0.25]3)(-[4,0.3]H_2))
	=[2,0.8](-[4.8,0.25]5)(-[3,0.7](=[2,0.7]O)(-[4.7,0.7]HO)(-[6,0.25]6))
	-[0.5,0.8]N(-[5.5,0.25]7)(-[,0.3]H)
	=[6.55,0.8]
		(-[4,0.2]8)
		-[5.25,0.6]
}
+
\chemfig{
C
	(-[4,0.25]H)
	(-[,0.5]NH_2)
	(-[6,0.5]COOH)
	(-[2,0.5]C
		(-[,0.3]H_2)
		(-[2,0.5]COOH)
	)
}
+ATP

\begin{tikzpicture} 
\draw [<->] (0,0) to node[above] {PAICS(E2);^{2+}$} (1,0); 
\end{tikzpicture}

\chemfig{
	\fbox{R}-[2,0.8]N(-[2,0.25]9)
	-[3.5,0.6](-[3.3,0.25]4)(-[4.5,0.7]N(-[2,0.25]3)(-[4,0.3]H_2))
	=[2,0.8](-[4.8,0.25]5)(-[3,0.7](=[2,0.7]O)
	(
		-[4,0.8]NH_2
			-[4,0.5]C
				(-[4,0.25]H)
				(-[6,0.5]COOH)
				(-[2,0.5]C
					(-[,0.3]H_2)
					(-[2,0.5]COOH)
				)
	)
	(-[6,0.25]6))
	-[0.5,0.8]N(-[5.5,0.25]7)(-[,0.3]H)
	=[6.55,0.8]
		(-[4,0.2]8)
		-[5.25,0.6]
}
+ADP+$

\end{document}