McGarry A, Gahan P B
Histochemistry. 1985;83(6):551-4. doi: 10.1007/BF00492459.
A quantitative cytochemical assay for UDP-D-glucose dehydrogenase (UDPGD) activity employing scanning and integrating microdensitometry has been revised and applied to a study of this enzyme during the initiation of secondary cell wall biosynthesis during the formation of primary vascular tissues in roots of Pisum sativum L. cv Meteor. The reaction involves the use of NBT as final electron acceptor and is inhibited 10-fold by either 10 mM UDP-D-xylose or 25 mM UDP-D-glucuronic acid, two molecules involved in feed-back inhibition of UDPGD activity in vivo. UDPGD is a far-from equilibrium enzyme representing a flux-generating step in the biosynthesis of precursors for hemicelluloses involved in secondary cell wall construction, and can be demonstrated to increase sharply in activity in cells of the developing primary vascular elements. This changed activity occurs 18-20 cells back from the root cap junction and coincides with the first cells containing the activated programme for secondary cell wall synthesis.
一种利用扫描和积分显微密度测定法对UDP-D-葡萄糖脱氢酶（UDPGD）活性进行的定量细胞化学分析方法已得到改进，并应用于研究豌豆（Pisum sativum L. cv Meteor）根中初生维管组织形成过程中次生细胞壁生物合成起始阶段的这种酶。该反应使用NBT作为最终电子受体，并且受到10 mM UDP-D-木糖或25 mM UDP-D-葡萄糖醛酸的10倍抑制，这两种分子在体内参与UDPGD活性的反馈抑制。UDPGD是一种远离平衡的酶，代表参与次生细胞壁构建的半纤维素生物合成前体的通量生成步骤，并且可以证明在发育中的初生维管元件细胞中其活性急剧增加。这种活性变化发生在距根冠连接处向后18 - 20个细胞处，并且与第一个含有激活的次生细胞壁合成程序的细胞相吻合。
