ABSTRACT
It was a rite of passage in the Gill laboratory to purify human hemoglobin, from our own blood, and measure a high-precision oxygen-binding curve with the famed Gill thin-layer spectroscopic apparatus, only to extract the four Adair constants under the carefully specied conditions of the experiment with home-fashioned soware to perform the nonlinear regression analysis. Human hemoglobin was a touchstone of the laboratory. Numerous structures had been determined by x-ray diraction, in their distinctly dierent oxy and deoxy states. It was a textbook example of a quaternary protein structure and the best studied example of cooperative binding in a biological system with the S-shaped oxygenbinding curve and steep Hill slope. Still, the structure-function mechanism responsible for its positive cooperativity was not fully elucidated. e answer bordered on an obsession for Stan and a few other devoted hemoglobinologists. e weight of facts was stacked in favor of the MWC allosteric model. Gill’s unique mastery of theory and experiment coupled with a talent and penchant for the design and construction of instruments proved to be a powerful combination in the search for the deeper mysteries of macromolecular function in hemoglobin A (HbA). While I shared the laboratory’s enthusiasm for quantitative approaches, it was a dierent class of respiratory proteins that was to draw my attention.
