Please use this identifier to cite or link to this item: http://hdl.handle.net/10397/28480
Title: Cloning and characterization of Arabidopsis thaliana pyridoxal kinase
Authors: Lum, HK
Kwok, F
Lo, SCL 
Keywords: Arabidopsis (pyridoxal kinase)
Gene expression (pyridoxal kinase)
Pyridoxal 5′-phosphate
Pyridoxal kinase
Vitamin B6 metabolism
Issue Date: 2002
Publisher: Springer-Verlag
Source: Planta, 2002, v. 215, no. 5, p. 870-879 How to cite?
Journal: Planta 
Abstract: Pyridoxal kinase (PK; EC 2.7.1.35), a key enzyme in vitamin B6 metabolism, was cloned from Arabidopsis thaliana (L.) Heynh. and characterized. The amino acid sequence of the A. thaliana PK was found to be similar to the mammalian enzyme, with a homology of more than 40%. Characterization studies showed that the kinase is a dimeric molecule consisting of two identical subunits, each subunit having a molecular mass of approximately 35 kDa. The enzyme exhibited maximal activity at pH 6.0. Similar to the mammalian enzyme, the enzyme from A. thaliana preferred Zn2+ instead of the commonly used Mg2+ as the divalent cation for catalysis. Under optimal conditions, the Vmax of the enzyme was 604 nmol pyridoxal 5′-phosphate (PLP) mg-1 min-1, and the Km values for pyridoxal and ATP were 688 μM and 98 μM, respectively. Examination of levels of enzyme expression showed that leaves, stems, roots and flowers can generate PLP independently at similar levels. Furthermore, expression of the PK gene in A. thaliana seeds was found to start 60 h after imbibition. Results from the present study suggest that plant tissues depend on PK for the production of PLP.
URI: http://hdl.handle.net/10397/28480
ISSN: 0032-0935
DOI: 10.1007/s00425-002-0799-0
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