结构
2-磷酸-4-(胞苷5'-二磷酸)-2-C-甲基-D-赤藓醇(CDP-ME2P)是甲基赤藓醇4-磷酸(MEP)途径中的磷酸化中间产物。分子中含有胞苷二磷酸基团与赤藓醇骨架,2位碳上额外携带一个磷酸基团,区别于前体4-(胞苷5'-二磷酸)-2-C-甲基-D-赤藓醇(CDP-ME)。
$结构式:$
-
\usepackage{chemfig}
\usetikzlibrary{decorations.pathmorphing}
\definecolor{cpk_P}{rgb}{1.00, 0.50, 0.00} % P
\begin{document}
\chemfig[atom sep=2em,cram width=3pt]{
(-[3.3,]
(<:[1.3,]O-[,0.54,,,transparent]
{\chemmove{\draw[ultra thick,green,fill=cpk_P,line width=2pt] (0.1,0.12)circle(6pt);}P}
)
(<[2.7,])
(-[4.7]
(-[6]OH)
)
)
(<[6,]OH)
% P
-[0.7,]-[7.3,]O(-[0,0.54,,,,transparent]{\chemmove{\draw[ultra thick,green,fill=cpk_P,line width=2pt] (0.1,0.12)circle(6pt);}P}
-[0,1,,,decorate,decoration=snake]{\chemmove{\draw[ultra thick,green,fill=cpk_P,line width=2pt] (0.1,0.12)circle(6pt);}P}
-[,1]O-CH_2-[6,]
% 腺苷
(-[6,]H)
(-[0.75,1.2]O)
<[6.75,]
(-[6,1,,2]HO)
(-[2,0.8]H)
-[,,,, line width=2pt]
(-[6,]OH)(-[2,0.8]H)>[1.25,](-[3.25,])
(-[6,]H)
(-[2,]N
*6(-(=O)-[,,,1]N=(-NH_2)-=-)
)
% 下边界支撑
-[6,0.5,,,,transparent])
}
\end{document}^1
功能
CDP-ME2P由CDP-ME激酶催化4-(胞苷5'-二磷酸)-2-C-甲基-D-赤藓醇(CDP-ME)磷酸化生成,消耗一分子[[ATP:三磷酸腺苷]]。该产物随后被MEP-CPP合酶环化,释放CMP生成甲基赤藓糖醇环二磷酸(MECDP)。此步骤是MEP途径由线性中间体向环状结构转变的关键过渡。
调控
CDP-ME2P的积累水平受上游[[1-脱氧-D-木酮糖-5-磷酸(DXP)]]供给和下游环化反应速率的双重影响。在质体中,光照条件促进整个MEP途径的通量,间接调控CDP-ME2P的稳态浓度。其代谢水平可作为MEP途径活性的指示标志物。