The Absorption Spectra of Protoheme and Heme a Complexes with Amino Acids and Related Compounds

Much information about the heme-binding groups of hemoproteins have been obtained from model studies with low molecular-weight heme complexes. Spectral models for cyto-chrome oxidase have been studied extensively by L e m b e r g and his co-workers. They first examined complexes of heme a with various proteins ( 1) and later complexes of heme a with detergents (2). They found that the a-band of reduced heme a in detergent solution shifted to a shorter wavelength when combined with carbon monoxide. The carbon monoxide-shift to a shorter wavelength is a characteristic of cytochrome oxidase [EC 1.9.3.1]. Their study was confirmed and extended by H o r i