Cloning and Characterization of Pyridoxal Kinase from Geobacillus sp. H6a

Pyridoxal kinase encoded by pdxK gene, is the important key enzyme in salvage pathway of vitamin B6 biosynthesis. The catalyzes phosphorylation 5′ alcohol groups free form into their 5′-phosphate forms that requires metal ion and ATP. have been reported many organisms except thermophilic bacterium. Therefore, this study aimed to clone, express characterize pyridoxal Geobacillus sp. H6a isolated from hot spring North Thailand. GhpdxK gene (810 base pairs) was inserted pET28a(+) plasmids at restriction site NdeI BamHI transformed E.coli BL21(DE3). expressed bacterium exhibits a homodimer, which each subunit had molecular mass about 32 kDa when examined SDS-PAGE gel filtration. showed maximal activity 70°C pH 8.0. obtained found be more active (>50%) broad range (6.0 – 9.0) than those previously reported. This prefers Mg2+ also accepts other cations less extent. Under optimal conditions, has higher affinity toward PN (20 ± 1.35 µM), while it same (100 0.76 µM) pyridoxamine 1.21 µM). Km value for ATP 4-amino-5-hydroxymethyl-2-methylpyridine were 8.99 1.76 µM 19 0.85 µM, respectively. With high temperature range, could considered as potential candidate future application particularly bioconversion B6.