Spectroscopic studies of mercury binding to metallothionein

✍ Scribed by Jadwiga A. Szymańska; Annie Y.C. Law; Andrzej J. Zelazowski; Martin J. Stillman

• Publisher: Elsevier Science
• Year: 1983
• Tongue: English
• Weight: 226 KB
• Volume: 79
• Category: Article
• ISSN: 0020-1693
• DOI: 10.1016/s0020-1693(00)95155-7

✦ Synopsis

observations of Packer and Deits that at least certain anions, such as SCN-[3], OCN-, and N3, give rise to uncompetitive inhibition patterns of CO2 hydration at high pH. This is illustrated for NT in Fig. 1. However, we offer an alternative interpretation to that of Packer and Deits. We will show that the uncompetitive pattern is a direct consequence of the kinetic mechanism which we have proposed previously [3, 41. The crucial point is that a strongly anion binding enzyme species, His-E-ZnZcOHz (see ref. [S]), precedes the rate-limiting step in catalysis.

Recently, some organic compounds that bind at or near the metal ion have received attention. One of these is phenol which has been shown to act as a competitive inhibitor of CO2 hydration and as a mixed noncompetitive inhibitor of HCOT dehydration [6]. We have also studied o-nitrophenol, 1,2,4triazole and tetrazole.

However, these inhibitors behave kinetically like anions and give rise to mixed uncompetitive-noncompetitive patterns in the COz hydration reaction at high pH.