Conformatonal analyss of bovine erythrocuprein from circular dichroism and infra-red spectra

Abstract

1. 1. The analysis of protein conformation from circular dichroism (C.D.) spectra by curve-fitting and matrix-rank determination is examined with reference to spectra of bovine crythrocuprcin. 2. 2. Poly-α-amino-acid reference spectra are not applicable to bovine erythrocuprein C.D. spectra in so far as they give least-square fits with negative percentages of secondary structure, in contrast to reference spectra derived from the C.D. spectra of the proteins ribonuclease, lysozyme, and myoglobin. The latter indicate the presence of a small percentage of α-helix and preponderance of unordered structure over β-structure in the protein. 3. 3. The presence of these structural modes and the preponderance of unordered structure is supported by the infra-red spectrum of the holoprotein in the amide I region. 4. 4. Matrix-rank analysis of a set of five independent C.D. spectra of bovine erythrocuprein in the far ultra-violet supports the three-component fit of the spectra by least squares.