Tryptophan mutants of human C5a anaphylatoxin: a fluorescence anisotropy decay and energy transfer study.
Biophys Chem
; 46(3): 237-48, 1993 May.
Article
in En
| MEDLINE
| ID: mdl-8343570
ABSTRACT
Three mutants of the anaphylatoxin C5a were prepared with positions 2, 64 and 70, respectively, substituted by tryptophan. The last mutant was additionally labelled at Cys27 for fluorescence energy transfer (FET) measurements. The structural integrity and biological activity of the molecules were not affected. Fluorescence anisotropy decay (FAD) measurements showed that the rotational correlation time for tryptophan decreases in the order [Trp2]rhC5a > [Trp64]rhC5a > [Trp70]rhC5a, indicating an increasing mobility of the side chain. Measurements of the fluorescence energy transfer from Trp70 to the 1,5-AEDANS group at Cys27 yielded a distance distribution of 2.4 +/- 0.8 nm. This value is compatible with the C-terminal chain being arranged as a slightly stretched helix pointing away from the body of the molecule.
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Collection:
01-internacional
Database:
MEDLINE
Main subject:
Tryptophan
/
Complement C5a
/
Anaphylatoxins
Limits:
Humans
Language:
En
Journal:
Biophys Chem
Year:
1993
Document type:
Article
Affiliation country:
Alemania