PDE6 is involved in visual signal transduction. It is known to be inhibited by toxic metal ions such as Pb2+, while native Zn2+ mediates its activity. In order to better understand its metal ion dependence and characterize its catalytic mechanism, we have investigated the relationship between free zinc concentration and enzyme activity. 4-(2-pyridylazo)resorcinol (PAR) along with select chelators were used in the development of a competition method that allows the spectrophotometric measurement of Zn(PAR)2 concentration in a solution with a known chelator to be compared to its concentration in a protein solution. The binding constant of the Zn2+-PDE complex can be determined indirectly by this method. The outcomes of metal ion binding and formation constant studies will be described.

Development of a method to quantitate divalent metal ion dependence of retinal phosphodiesterase

245th National Meeting (2013)

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