Oxygen-Carrying Proteins: a Comparison of the Oxygenation Reaction in Hemocyanin and Hemerythrin with That in Hemoglobin

Hemoglobin function in deep-sea and hydrothermal-vent endemic fish:Symenchelis parasitica(Anguillidae) andThermarces cerberus(Zoarcidae)

“…Curiously also, the overall heat of oxygenation of Hb I was not reduced by ATP addition (at pH 7.0, ∆H′=-44·kJ·mol -1 to -45·kJ·mol -1 in the absence and presence of ATP, respectively; not shown). Given the small variability of the intrinsic heats of oxygenation of metal-containing gas-binding proteins (Klotz and Klotz, 1955), these observations indicate the presence of other endothermic reactions that reduce ∆H′. A possible candidate is endothermic allosteric transitions, as in cathodic trout Hb I, where the low temperature sensitivity for CO binding is attributed to conformational changes conditioned to the molecules in the T-state (Wyman et al, 1977).…”

Resonance Raman Studies of the Electronic State of Oxygen in Hemerythrin

“…This nonheme pigment has Fe attached directly to side chains of residues of the polypeptide chain. Each subunit of hemerythrin contains 2 Fe atoms and binds 1 mol of 02.…”

“…It was suggested some years ago (2), on the basis of meager evidence, that conversion of deoxy-to oxyhemerythrin should be described by the following transition in electronic states:…”

Thermodynamics of oxygenation-linked proton and lactate binding govern the temperature sensitivity of O2 binding in crustacean(Carcinus maenas) hemocyanin

“…Based on the exothermic nature of their oxygenation reactions (Klotz and Klotz, 1955), the O 2 affinities of metal-containing, gas-binding proteins decrease with increasing temperature. Apart from the intrinsic heat of oxygenation (⌬H O2 ), the overall heat of oxygenation (⌬HЈ) includes the heat of solution of oxygen (⌬H The ⌬HЈ values of crustacean Hc at physiological pH (7.6-7.8) vary tremendously (from -67 to +134·kJ·mol -1 ) (cf.…”