Knowledge Bank

Biological macromolecules are critically dependent upon a particular manner of folding for their biological activity. This, in turn, depends upon solvent composition, temperature, and other factors. Thus classical infrared sampling techniques which employ dried films, KBr pellets, or ``good’’ infrared solvents, destroy biologically native structures, and are of limited value in structure analysis. We have therefore studied a variety of metal-protein complexes in concentrated aqueous solution by infrared spectroscopy. Studies which illustrate the use of quantitative infrared spectroscopy for analysis of biological structures include determination of the temperature dependence of the equilibrium for azide $(N3-)$ bound ionically or covalently to metmyoglobin, and the use of isotope shift data in the study of carbon monoxide complexes with oxygen-carrying proteins from vertebrates and lower animal forms.