百科词条

C6：半乳糖（galactose）

smiles C C@@H 1 C@@H C@@H C@H C O1 O O O O O 半乳糖是 C6：葡萄糖（glucose）的C-4差向异构体，分子式为C₆H₁₂O₆。两者仅在C-4位羟基的空间构型上存在差异：葡萄糖为equatorial构型，半乳糖为axial构型。半乳糖同样可形成吡喃型六元环结构，存在α与β两种异头物。 $结构式：$ - 费

作者：admin

2026-08-16

3D结构

C([C@@H]1[C@@H]([C@@H]([C@H](C(O1)O)O)O)O)O

结构

半乳糖是[[C6：葡萄糖（glucose）]]的C-4差向异构体，分子式为C₆H₁₂O₆。两者仅在C-4位羟基的空间构型上存在差异：葡萄糖为equatorial构型，半乳糖为axial构型。

半乳糖同样可形成吡喃型六元环结构，存在α与β两种异头物。

$结构式：$

• 费歇尔投影式2

\usepackage{chemfig}
\begin{document}
\chemfig[atom sep=2em,cram width=2pt]{
(-[2,1.2,,,transparent])
	(-[0,]{\color{blue}OH})(-[4,]H)(-[2,,,]CH{\color{red}O})
	-[6,](-[4]{\color{green}HO})(-[0,]H)
	-[6,](-[4]{\color{pink}HO})(-[0,]H)
	-[6,](-{\color{Cyan}OH})(-[4,]H)(-[6]CH_2{\color{orange}OH})
}
\end{document}

• 键线式2

\usepackage{chemfig}
\begin{document}

\chemfig{
(-[2,1.5,,,transparent]) %上支撑
	(-[3.5,0.8]{\color{orange}HO}
		% P
		( % 上边界支撑
			-[2,0.5,,,,transparent]
		)
	)
	(-[0.5,0.8]
		(<[2,0.8]-[2,0.2,,,transparent]-[0,0.13,,,transparent]{\color{Cyan}OH})
		(-[7.5,0.8]
			(<[6,0.8]-[6,0.2,,,transparent]-[0,0.13,,,transparent]{\color{pink}OH})
			(-[.5,0.8]
				(<:[2,0.8]-[2,0.2,,,transparent]-[0,0.13,,,transparent]{\color{green}OH})
				(-[7.5,0.8]
					(<:[6,0.8]-[6,0.2,,,transparent]-[0,0.13,,,transparent]{\color{blue}OH})
					(-[.5,0.8]
						=[7.5,0.8]{\color{red}O}
						% P
						(
							% 上边界支撑
							-[2,0.5,,,,transparent]
						)
					)
				)
			)
		)
	)
}

\end{document}

• 哈沃斯投影式2 ：$\beta{}-d-呋喃半乳糖$（$\beta{}$-D-Galactofuranose）

\usepackage{chemfig}
\begin{document}

\chemname{
\chemfig[cram width=2pt]{
	%5-6
		(-[0.7,1.25]{\color{pink}O}
			(-[2,0.5,,,transparent]) %上支撑
		)
			%6
			(-[2,0.5]H)(-[6,1.8]C(-[,0.25,,,transparent]H)(-[4,0.35,,,transparent]{\color{Cyan}HO})(-[6,0.5]CH_2-[4,0.35,,,transparent]{\color{orange}HO})
				% 上边界支撑
				-[2,1.1,,,,transparent]
			)
	%4
	<[6.75,](-[2,0.35]-[2,0.15,,,transparent]-[0,0.13,,,transparent]{\color{green}OH})(-[6,0.5]H)
	%3
	-[,,,, line width=2pt](-[6,0.35,,]-[6,0.15,,,transparent]-[,0.13,,,transparent]{\color{blue}OH})(-[2,0.5]H)
	%2
    >[1.25,](-[2,0.35]-[2,0.15,,,transparent]-[0,0.13,,,transparent]{\color{red}OH})(-[3.3,1.05])
	%1
	-[6,0.5]H
}
}{}
\end{document}

• $\beta{}$-D-Galactopyranose

\usepackage{chemfig}
\definecolor{cpk_P}{rgb}{1.00, 0.50, 0.00}     % P
\begin{document}

\chemname{
\chemfig[cram width=2pt]{
	%[:-30]
	%C4
	(-[6,0.5]H)(-[2,0.35,,]-[2,0.15,,,transparent]-[4,0.13,,,transparent]{\color{pink}HO})
	*6(
	%C3
	<(-[6,0.5]H)(-[2,0.35]-[2,0.15,,,transparent]-[0,0.13,,,transparent]{\color{green}OH})
	%C2
	-[,1,,, line width=2pt](-[2,0.5]H)(-[6,0.35]-[6,0.15,,,transparent]-[0,0.13,,,transparent]{\color{blue}OH})
	%C1
	>(-[6,0.5]H)(-[2,0.35]-[2,0.15,,,transparent]-[0,0.15,,,transparent]{\color{red}OH})
	-{\color{Cyan}O}-
	    %C6
		(-[2.7,1]
			(-[1.3,1]{\color{orange}OH}
				% 上边界支撑
				-[2,0.5,,,,transparent]
			)
		)
	%C5
    -		
	)
}
}{}

\end{document}

功能

半乳糖是乳糖（lactose）的组成成分之一。乳糖由一分子半乳糖与一分子[[C6：葡萄糖（glucose）]]以β-1,4-糖苷键连接。半乳糖还参与甘油磷脂和糖蛋白的合成，是[[0. 细胞膜]]糖脂组分的重要前体。

代谢

半乳糖经Leloir途径进入代谢。首先由半乳糖激酶磷酸化为半乳糖-1-磷酸，再经半乳糖-1-磷酸尿苷酰转移酶转化为UDP-葡萄糖，最终进入[[0. 糖酵解（glycolysis）]]途径。

先天性半乳糖血症即因该途径酶缺陷所致，患者无法正常代谢半乳糖。UDP-半乳糖也可异构化为UDP-葡萄糖，后者参与[[糖原（glycogen）]]合成或经[[0. 糖酵解（glycolysis）]]生成[[C3：丙酮酸（pyruvate）]]供能。

参考资料

• Lehninger, A.L. *Principles of Biochemistry*

• Nelson, D.L. & Cox, M.M. *Lehninger Principles of Biochemistry*