title: Interaction between pyridoxal kinase and pyridoxal-5-phosphate-dependent enzymes.
abstract: The interactions of two pyridoxal-5-phosphate (PLP)-dependent enzymes, alanine aminotransferase (ALT) and glutamate decarboxylase (GAD), with pyridoxal kinase (PK) were studied by fluorescence polarization as well as surface plasmon resonance techniques. The results demonstrated that PK can specifically bind to ALT and GAD. Moreover, binding profiles of both enzymes to immobilized PK were altered by excess amount of PLP. The equilibrium affinity constants for ALT in the absence and presence of PLP are 20.4 x 10(4) M(-1)and 6.7 x 10(4) M(-1), and for GAD are 37 x 10(4) M(-1)and 20.8 x 10(4) M(-1), respectively. It appears that specific interactions occur between PK and PLP-dependent enzymes, and the binding affinities of PK for PLP-dependent enzymes decrease in the presence of PLP. The results support our hypothesis that PLP transfer from PK to PLP-dependent enzymes requires a specific interaction between PK and the enzyme.
authors.affiliation: The Central Laboratory of the Institute of Molecular Technology for Drug Discovery and Synthesis, Department of Applied Biology and Chemical Technology, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong SAR, P.R.C.
authors.forename: Pik-Yuen
authors.initials: PY
authors.lastname: Cheung
authors.forename: Chi-Chun
authors.initials: CC
authors.lastname: Fong
authors.forename: Kang-To
authors.initials: KT
authors.lastname: Ng
authors.forename: Wan-Chuen
authors.initials: WC
authors.lastname: Lam
authors.forename: Yun-Chung
authors.initials: YC
authors.lastname: Leung
authors.forename: Chun-Wai
authors.initials: CW
authors.lastname: Tsang
authors.forename: Mengsu
authors.initials: M
authors.lastname: Yang
authors.forename: Man-Sau
authors.initials: MS
authors.lastname: Wong
mesh_terms: D000410:Alanine Transaminase / Q000378:metabolism*; D000818:Animals; D004800:Enzymes, Immobilized / Q000378:metabolism; D005454:Fluorescence Polarization; D005968:Glutamate Decarboxylase / Q000302:isolation & purification / Q000378:metabolism*; D007700:Kinetics; D011485:Protein Binding; D011731:Pyridoxal Kinase / Q000302:isolation & purification / Q000378:metabolism*; D011732:Pyridoxal Phosphate / Q000378:metabolism*; D011994:Recombinant Proteins / Q000378:metabolism; D013552:Swine; D013997:Time Factors
chemical_list: D004800:Enzymes, Immobilized; D011994:Recombinant Proteins; D011732:Pyridoxal Phosphate; D000410:Alanine Transaminase; D011731:Pyridoxal Kinase; D005968:Glutamate Decarboxylase