Interação hidrofóbica de mioglobina com spin label TEMPO. / Hydrophobic interaction od myoglobin with the spin label TEMPO.

AUTOR(ES)

Oswaldo Baffa Filho

DATA DE PUBLICAÇÃO

1980

RESUMO

Type A myoglobin single crystals were doped with the 2, 2, 6, 6 -tetramethyl - 1 - oxyl (TEMPO) spin label by a diffusion process. We observed one isotropic spin label type, and another anisotropic type which shows an axial symmetry with A// = 23,4 G, A⊥ = 20, 6 G and g = 2,0056. The rotational correlation times are estimated to be a τ// = 7,2.10-9s and τ⊥ = 4,8.10-9s. A quantitative analysis on the hydrophobic nature of the residues situated inside the molecule suggests, as a possible site for the TEMPO, the pocket formed in the region of tyrosine 103-helix H and tyrpsine 151 - terminal 3HC. This pocket is of sufficient size to contain the radical and is positioned in such fashion as to be a compatible with the heme group, this not holding for other sites. A temperature induced conformational change in the protein is observed in the region 20-30°, which may be ascribed to a shift of the H helix. This fact, together with the finds of other authors, seems to indicate a generalized temperature induced conformational alteration in the molecule.

ASSUNTO(S)

hemoproteínas hemoproteins mioglobina myoglobin spin-label spin-label tempo tempo

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