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Master's Dissertation
DOI
10.11606/D.54.1980.tde-10012011-090621
Document
Author
Full name
Oswaldo Baffa Filho
E-mail
Institute/School/College
Knowledge Area
Date of Defense
Published
São Carlos, 1980
Supervisor
Title in Portuguese
Interação hidrofóbica de mioglobina com spin label TEMPO.
Keywords in Portuguese
Hemoproteínas
Mioglobina
Spin-label
TEMPO
Abstract in Portuguese
Cristais de mioglobina tipo A foram dopados por processo de difusão com o marcador 2, 2, 6, 6 - tetrametil-l-oxil (TEMPO). Observa-se a existência de uma espécie de marcador isotrópica e outra anisotrópica, que exibe uma simetria axial com A// = 23,4 G, A⊥ = 20, 6 G e g = 2,0056. São estimados os tempos de correlação rotacional τ// = 7,2.10-9s e τ = 4,8.10-9s. Uma análise do grau de hidrofobicidade dos resíduos, situados na parte interna da molécula, sugere como um possível sitio de localização para o TEMPO o bolso formado na região da tirosina 103 - hélice H e 151 - terminal 3HC. Este bolso tem tamanho suficiente para abrigar o radical e posição coerente com a heme, o que não acontece com outros sítios. Observa-se uma mudança conformacional da proteína, induzida pela temperatura na região 20-30°. Esta pode ser atribuída a um movimento da hélice H. Este resultado somado ao de outros autores indica uma mudança conformacional de grande extensão na molécula.
Title in English
Hydrophobic interaction od myoglobin with the spin label TEMPO.
Keywords in English
Hemoproteins
Myoglobin
Spin-label
TEMPO
Abstract in English
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.
 
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Publishing Date
2011-01-31
 
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