The Catalytic Properties of Alkaline Phosphatases
under Various Conditions

L. F. Atyaksheva, E. S. Chukhrai, and O. M. Poltorak^†

Faculty of Chemistry, Moscow State University, Moscow, 119899 Russia

e-mail: poltorak@phys.chem.msu.ru

Received June 26, 2007

Abstract—A comparative study was performed to examine the catalytic properties of alkaline phosphatases
from bacteria Escherichia coli and bovine and chicken intestines. The activity of enzyme dimers and tetramers
was determined. The activity of the dimer was three or four times higher than that of the tetramer. The maximum
activity and affinity for 4-nitrophenylphosphate was observed for the bacterial alkaline phosphatase (K_M =
1.7 10⁵ M, V_max = 1800 mol/(min mg of protein) for dimers and V_max = 420 mol/(min mg of protein) for
tetramers). The Michaelis constants were equal for two animal phosphatases in various buffer media (pH 8.5)
((3.5 0.2) 10⁴ M). Five buffer systems were investigated: tris, carbonate, hepes, borate, and glycine buffers,
and the lowest catalytic activity of alkaline phosphatases at equal pH was observed in the borate buffer (for
enzyme from bovine intestine, V_max = 80 mol/(min mg of protein)). Cu²⁺ cations formed a complex with
tris(oxymethyl)-aminomethane (tris-HCl buffer) and inhibited the intestine alkaline phosphatases by a non-
competitive mechanism.

DOI: 10.1134/S0036024408110265

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