ISSN:
1432-1017
Keywords:
Time-resolved fluorescence
;
Multi-exponential decay
;
Protein substates
;
Unfolded protein
;
NATA
Source:
Springer Online Journal Archives 1860-2000
Topics:
Biology
,
Physics
Notes:
Abstract The tryptophan fluorescence of two membrane proteins (outer membrane protein A and lactose permease), a 21-residue hydrophobic peptide, three soluble proteins (rat serum albumin, ribonuclease TI, and azurin), and N-acetyltryptophanamide (NATA) was investigated by time-resolved measurements extended over 65 ns. A long lifetime component with a characteristic time of 25 ns and an amplitude below 1% was found for outer membrane protein A, lactose permease, the peptide in lipid membranes, and azurin in water, but not for rat serum albumin, ribonuclease TI, and NATA in water. When outer membrane protein A was dissolved and unfolded in guanidinum hydrochloride, the long lifetime component disappeared. Hence, a hydrophobic environment seems to be a necessary requirement for the long lifetime component to be present. However, NATA dissolved in butanol does not exhibit the long lifetime component, while the peptide dissolved in the same solvent under conditions which preserve its helical structure does show the long lifetime. Thus, a regular secondary structure for the polypetide chain to which the tryptophan residue belongs seems to be a second necessary requirement for the long lifetime component to be present. The long lifetime component may therefore be seen in the context of protein substates.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00196829
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