Rat osseous plate alkaline phosphatase: mechanism of action of manganese ions

✍ Scribed by F. A. Leone; P. Ciancaglini; J. M. Pizauro; A. A. Rezende

• Publisher: Springer Netherlands
• Year: 1995
• Tongue: English
• Weight: 385 KB
• Volume: 8
• Category: Article
• ISSN: 1572-8773
• DOI: 10.1007/bf00156163

✦ Synopsis

Polidocanol-solubilized osseous plate alkaline phosphatase was modulated by manganese ions in a similar way as by zinc ions. For concentrations up to 1.0 nM, the enzyme was stimulated by manganese ions, showing site-site interactions (n = 2.2). However, larger concentrations (> 0.1/w) were inhibitory. Manganese ions could play the role of zinc ions stimulating the enzyme synergistically in the presence of magnesium ions (Kd = 7.2/IM; V = 1005.5 U mg-1). Manganese ions could also play the role of magnesium ions, stimulating the enzyme synergistically in the presence of zinc ions (K d = 2.2/z~a; V = 1036.7 U mg-1). However, manganese ions could not substitute for zinc and magnesium at the same time since ion assymetry is necessary for full activity of the enzyme. A steady-state kinetic model for the modulation of enzyme activity by manganese ions is proposed.