کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
---|---|---|---|---|
2015238 | 1067538 | 2011 | 7 صفحه PDF | دانلود رایگان |
![عکس صفحه اول مقاله: Characterization of enzymes involved in the interconversions of different forms of vitamin B6 in tobacco leaves Characterization of enzymes involved in the interconversions of different forms of vitamin B6 in tobacco leaves](/preview/png/2015238.png)
There are six different vitamin B6 (VB6) forms, pyridoxal (PL), pyridoxamine (PM), pyridoxine (PN), pyridoxal 5′-phosphate (PLP), pyridoxamine 5′-phosphate (PMP) and pyridoxine 5′-phosphate (PNP). PLP is a coenzyme required by more than 100 cellular enzymes. In spite of the importance of this vitamin, the understanding of VB6 metabolic conversion in plants is limited. In this study, we developed a sensitive and reliable method to assay VB6-metabolizing enzyme activities by monitoring their products visually using high-performance liquid chromatography. With this method, the reactions catalyzed by PL/PM/PN kinase, PMP/PNP oxidase, PM-pyruvate aminotransferase, PL reductase and PLP phosphatase were all nicely detected using crude protein extracts of tobacco leaves. Under optimal in vitro conditions, specific activities of those enzymes were 0.15 ± 0.03, 0.10 ± 0.03, 0.08 ± 0.02, 0.64 ± 0.13 and 23.08 ± 1.98 nmol product/min/mg protein, respectively. This is the first report on the conversion between PM and PL catalyzed by PM-pyruvate aminotransferase in plants. Furthermore, the PL reductase activity was found to be heat inducible. Our study sheds light on the VB6 metabolism taking place in plants.
► A sensitive and reliable method for assays of VB6-metabolizing enzyme activities.
► The reaction catalyzed by PM-pyruvate aminotransferase was first detected in plants.
► The PL reductase activity was found to be heat inducible.
Journal: Plant Physiology and Biochemistry - Volume 49, Issue 11, November 2011, Pages 1299–1305