Molybdenum cofactor of higher plants: biosynthesis and molecular biology
Molybdenum cofactor of higher plants: biosynthesis and molecular biology
复制标题
高等植物的钼辅因子：生物合成和分子生物学
作者：
R. Mendel
钼(Mo)对植物、动物和微生物的重要性早已为人所知(Coughlan 1980年回顾)。事实上，过渡元素钼对(几乎)所有生物体都是必不可少的，并且已经在20多种不同的、主要是细菌的酶中发现了催化各种氧化还原反应的酶(Hille 1996；Stiefel 1996)。50多年前首次记录了大田植物的钼缺乏(Gupta 1997年回顾)，并可追溯到硝酸还原酶(NR)活性的缺乏(Hewitt 1983)，而NR活性催化了无机氮同化的关键步骤。真核生物和原核生物的核受体在活性中心都含有作为催化金属的钼(Hille 1996)。在高等植物中，已描述了更多的钼酶：(I)黄嘌呤脱氢酶参与嘌呤的分解代谢，并对某些豆科植物具有重要意义，在某些豆科植物中，黄嘌呤脱氢酶是合成尿囊酸的关键(Nguyen 1986)，以及(Ii)醛氧化酶(S)最近被证明催化植物激素吲哚乙酸生物合成的最后一步(Koshiba等人)。和脱落酸(Walker-Simmons等人)。1989年；泰勒1991年)。因此，土壤中钼的缺乏或细胞利用钼能力的突变障碍会导致基本代谢功能的丧失
The importance of molybdenum (Mo) for plants, animals and microorganisms has been known for a long time (reviewed by Coughlan 1980). In fact, the transition element Mo is essential for (nearly) all organisms and has been found in more than 20 distinct mostly bacterial enzymes catalyzing diverse redox reactions (reviewed by Hille 1996; Stiefel 1996). Molybdenum deficiencies in field-grown plants were first recorded more than 50 years ago (reviewed by Gupta 1997) and could be traced back to a lack of nitrate reductase (NR) activity (Hewitt 1983) which catalyzes the key step in inorganic nitrogen assimilation. Eukaryotic and also prokaryotic NRs contain Mo as catalytic metal in the active center (Hille 1996). In higher plants, further Mo-enzymes have been described: (i) xanthine dehydrogenase is involved in purine catabolism and has importance for certain legumes in which it is crucial for synthesizing allantoic acid as the transport form of nitrogen (reviewed by Nguyen 1986), and (ii) aldehyde oxidase(s) has recently been shown to catalyze the last step in the biosynthesis of the phytohormones indolyl acetic acid (Koshiba et al. 1996) and abscisic acid (Walker-Simmons et al. 1989; Taylor 1991), respectively. Hence a shortage of Mo in the soil or a mutational block of the cellular ability to use Mo leads to the loss of essential metabolic functions