植物维生素B_6从头合成与代谢转换研究进展

Review on the denovoSynthesis and Metabolic Conversions of Vitamin B_6 in Plants

维生素B6是一组可相互转换的吡啶衍生物的总称,包括吡哆醇、吡哆胺、吡哆醛、磷酸吡哆醇、磷酸吡哆胺和磷酸吡哆醛。其中,磷酸吡哆醛是140多种细胞酶的辅酶。至今发现两种VB6从头合成途径,DXP(1-脱氧-D-木酮糖-5-磷酸)依赖途径和DXP非依赖途径,前者仅存在于大肠杆菌和少量其他细菌,后者存在于其他所有VB6自养生物。除了VB6的从头合成,所有细胞生物体内还存在一条相似的补救途径,补救途径实现VB6各型的代谢转换。该文对近年来国内外有关植物VB6从头合成和代谢转换研究进展进行综述。

Vitamin B6（VB6）is a generic term referring to six interconvertiblecompounds,pyridoxine,pyridoxal,pyridoxamine and their phosphorylated derivatives,pyridoxine 5′-phosphate,pyridoxal 5′-phosphate and pyridoxamine 5′-phosphate.Pyridoxal 5′-phosphate is the catalytically active form of VB6,andacts as cofactor in more than 140 different enzyme reactions.VB6 is synthesized de novo by two different enzymatic pathways,the DXP（1′-deoxy-D-xylulose-5′-phosphate）-dependent pathway of E.coli and a few other bacteria,and the DXP-independent pathway found in almost all other organisms,except for animals.In addition to the de novo pathways,another pathway is found in all organisms,and functions to convert the six different VB6 forms between each other.This pathway is called the＂salvage pathway＂.This article summarizes the current knowledge on the de novo synthetic pathway and the salvage pathway of VB6 in plants.