Effects of Oxodiperoxovanadate (V) Complexes on the Activity of Green Crab (Scylla serrata) Alkaline Phosphatase

X.-W. Zhou^1,2, Q.-X. Chen^1*, Z. Chen², Z.-Q. He¹, and H.-M. Zhou^1,3*

¹Department of Biology, Xiamen University, Xiamen 361005, People's Republic of China

²Department of Chemistry, Xiamen University, Xiamen 361005, People's Republic of China

³Department of Biological Science and Biotechnology, Tsinghua University, Beijing 100084, People's Republic of China; fax: +8610 62785505; E-mail: zhm-dbs@mail.tsinghua.edu.cn

^* To whom correspondence should be addressed.

Received February 14, 2000

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Green crab (Scylla serrata) alkaline phosphatase (EC 3.1.3.1) is a metalloenzyme that catalyzes the nonspecific hydrolysis of phosphate monoesters. The effects of some pollutants in seawater on the activity of the enzyme will result in the loss of the biological function of the enzyme, which will affect the exuviating crab shell and threaten the survival of the animal. In the present paper, the effects of four oxodiperoxovanadate (V) complexes on the activity of green crab alkaline phosphatase have been studied. The results show that these vanadate derivatives can lead to reversible inactivation. The equilibrium constants for binding of inhibitors with the enzyme and/or the enzyme-substrate complexes have been determined. The results show that sodium (2,2´-bipyridine)oxodiperoxovanadate, pV(bipy), and potassium oxodiperoxo-(1,10-phenanthroline)vanadate, pV(phen), are competitive inhibitors, while potassium picolinato-oxodiperoxo-vanadate, pV(pic), and oxalato-oxodiperoxovanadate, pV(ox), are mixed-type inhibitors. These results suggest that pV(bipy) is a considerably more potent competitive inhibitor than pV(phen) and that the competitive inhibition effect of pV(pic) is stronger than that of pV(ox), but the non-competitive inhibition effect of pV(ox) is stronger than that of pV(pic).

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KEY WORDS: alkaline phosphatase, oxodiperoxovanadate, inhibition, inactivation

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