The molecular origin of body temperature in homeothermic species.

We propose the Interfacial Water Quantum-transition model (IWQ model) as a novel paradigm explaining temperature-dependent structural and functional transitions (discontinuities) observed in proteins. The central postulate states that experimentally measured critical temperatures, T_C, are related to physical reference temperatures, T_W, defined by rotational quantum transitions of temporarily free water molecules in the protein-water interface. Applicability of this concept is demonstrated using transitions observed in two disparate model systems, viz., hemoglobin and thermosensitive TRP channels. We propose that the same mechanism underlies the definition of basal body temperatures in homeotherms, the reference temperature for humans being T_W=36.32°C. Specifically, we demonstrate that the body temperatures of both human and chicken (representing the two classes of homeothermic vertebrates) not only coincide with quantum-transition reference temperatures but are also related to pronounced transitions in hemoglobin oxygen saturation. This suggests that the evolution of body temperatures in different homeothermic species might involve an interplay between critical parameters of oxygen supply on the one hand and quantum-physical rotational transition temperatures of water on the other. Casting the IWQ-model concept into a concise formula: Proteins sense and water sets critical physiological temperatures.