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Binding Of Urate And Caffeine To Hemocyanin Of The Lobster Homarus Vulgaris (E.) As Studied By Isothermal Titration Calorimetry †, Michael A. Menze, Nadja Hellmann, Heinz Decker, Manfred K. Grieshaber

Faculty Research & Creative Activity

Hemocyanin serves as an oxygen carrier in the hemolymph of the European lobster Homarus Vulgaris. The oxygen binding behavior of the pigment is modulated by metabolic effectors such as lactate and urate. Urate and caffeine binding to 12-meric hemocyanin (H. Vulgaris) was studied using isothermal titration calorimetry (ITC). Binding isotherms were determined for fully oxygenated hemocyanin between pH 7.55 and 8.15. No pH dependence of the binding parameters could be found for either effector. Since the magnitude of the Bohr effect depends on the urate concentration, the absence of any pH dependence of urate and caffeine binding to oxygenated hemocyanin …