Identification and characterization of a pyridoxal 5'-phosphate phosphatase in tobacco plants.

Pyridoxal 5'-phosphate (PLP), the catalytically active form of vitamin B, is an important cofactor for many biochemical transformations. PLP is also a very reactive molecule, and the most well-established mechanism for maintaining low levels of free PLP is its dephosphorylation by phosphatases. In our previous study, the crude enzyme extract from tobacco leaves rapidly hydrolyzed PLP at a pH optimum of 5.

Isolation and characterization of the 5'-flanking region of the human PDXK gene.

Pyridoxal kinase is a key enzyme for the biosynthesis of pyridoxal 5'-phosphate. Pyridoxal 5'-phosphate is the catalytically active form of vitamin B, and acts as a cofactor in >140 different enzyme reactions. It is still unknown how the kinase synthesis is regulated in the cells, and nothing has been reported about the gene promoter.

Identification and characterization of a pyridoxal 5'-phosphate phosphatase in the silkworm (Bombyx mori).

Vitamin B comprises six interconvertible pyridine compounds, among which pyridoxal 5'-phosphate (PLP) is a coenzyme for over 140 enzymes. PLP is also a very reactive aldehyde. The most well established mechanism for maintaining low levels of free PLP is its dephosphorylation by phosphatases.

Direct and indirect effects of RNA interference against pyridoxal kinase and pyridoxine 5'-phosphate oxidase genes in Bombyx mori.

Vitamin B6 comprises six interconvertible pyridine compounds (vitamers), among which pyridoxal 5'-phosphate is a coenzyme involved in a high diversity of biochemical reactions. Humans and animals obtain B6 vitamers from diet, and synthesize pyridoxal 5'-phosphate by pyridoxal kinase and pyridoxine 5'-phosphate oxidase. Currently, little is known on how pyridoxal 5'-phosphate biosynthesis is regulated, and pyridoxal 5'-phosphate is supplied to meet their requirement in terms of cofactor.

Effect of exogenous hormones on transcription levels of pyridoxal 5'-phosphate biosynthetic enzymes in the silkworm (Bombyx mori).

Vitamin B6 includes 6 pyridine derivatives, among which pyridoxal 5'-phosphate is a coenzyme for over 140 enzymes. Animals acquire their vitamin B6 from food. Through a salvage pathway, pyridoxal 5'-phosphate is synthesized from pyridoxal, pyridoxine or pyridoxamine, in a series of reactions catalyzed by pyridoxal kinase and pyridoxine 5'-phosphate oxidase.

Enzymatic conversion from pyridoxal to pyridoxine caused by microorganisms within tobacco phyllosphere.

Vitamin B6 (VB6) comprises six interconvertible pyridine compounds (vitamers), among which pyridoxal 5'-phosphate (PLP) is a coenzyme involved in a high diversity of biochemical reactions. In plants, PLP is de novo synthesized, and pyridoxine (PN) is usually maintained as the predominant B6 vitamer. Although the conversion from pyridoxal (PL) to PN catalyzed by PL reductase in plants has been confirmed, the enzyme itself remains largely unknown.

Enzymatic transamination of pyridoxamine in tobacco plants.

Vitamin B6 (VB6) comprises a group of pyridine compounds that are involved in a surprisingly high diversity of biochemical reactions. Humans and animals depend largely on plants for their VB6 nutrition. Many studies have focused on biosynthesis of VB6 and comparatively little is known about VB6 metabolic conversion in plants.

Effect of abiotic stress on the abundance of different vitamin B6 vitamers in tobacco plants.

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), of which PLP is the active form. Although transcriptional regulation of the genes involved in the de novo and salvage pathways of PLP syntheses after stress treatments has been described for Arabidopsis thaliana and tobacco plants, it remains open as to whether this in turn affects VB6 levels. In this study, the effects of chilling, UV radiation, intensity of illumination, osmotic pressure, oxidative and drought stresses on the abundance of different B6 vitamers in tobacco plants were examined by using high performance liquid chromatography (HPLC).

Characterization of an acid phosphatase responsible for hydrolysis of pyridoxal 5'-phosphate in tobacco plants.

Pyridoxal 5'-phosphate (PLP), the active form of vitamin B(6), is an important cofactor for many enzymatic reactions. PLP is also a very reactive molecule, and the hydrolysis of PLP is crucial for controlling intracellular PLP concentrations. However, little is known about the enzymatic hydrolysis of PLP in plants.

Functional significance of some particular amino acid residues in Bombyx mori pyridoxal kinase.

Pyridoxal kinase (PLK; EC 2.7.1.

Interconversions of different forms of vitamin B6 in tobacco plants.

There are six different vitamin B(6) (VB(6)) forms, pyridoxal (PL), pyridoxamine (PM), pyridoxine (PN), pyridoxal 5'-phosphate (PLP), pyridoxamine 5'-phosphate (PMP), and pyridoxine 5'-phosphate (PNP), of which PLP is the active form. Although plants are a major source of VB(6) in the human diet, and VB(6) plays an important role in plants, the mechanisms underlying the interconversions of different VB(6) forms are not well understood. In this study, in vitro tobacco plants were grown on Murashige and Skoog (MS) basal media supplemented with 100mg/L of PM, PL or PN and the abundance of the different B(6) vitamers in leaf tissue was quantified by high performance liquid chromatography (HPLC).

Bombyx mori pyridoxal kinase cDNA cloning and enzymatic characterization.

Pyridoxal kinase (PLK) (EC 2.7.1.