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Fluorescence dynamics studies of troponin C
Author(s) -
Steiner Robert F.,
Norris Lynn
Publication year - 1987
Publication title -
biopolymers
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.556
H-Index - 125
eISSN - 1097-0282
pISSN - 0006-3525
DOI - 10.1002/bip.360260713
Subject(s) - chemistry , rotational correlation time , conjugate , fluorescence , troponin c , molecule , crystallography , troponin , biophysics , analytical chemistry (journal) , stereochemistry , chromatography , physics , psychology , mathematical analysis , mathematics , organic chemistry , quantum mechanics , psychiatry , myocardial infarction , biology
The time decay of fluorescence anisotropy for a dansylaziridine (DANZ) conjugate with Met‐25, which lies within the N‐terminal lobe of troponin C (TnC), shows at 10 and 25°C a longer correlation time characteristic of the entire molecule and a shorter correlation time arising from a more localized motion of the probe. In the absence of Ca 2+ , the amplitude of the shorter correlation time increases, suggesting an increased mobility of the probe. At 40°C, in both the absence and presence of Ca 2+ , a significant increase in probe mobility occurs. A 2,6‐toluidinyl naphthalene sulfonate (2,6‐TNS) complex with Ca 2+ ‐liganded TnC shows only the longer correlation time at 12 and 25°C. An N ‐(iodoacetylaminoethyl‐5‐naphthylamine‐1‐sulfonate) conjugate with Cys‐98 shows both a long and a short correlation time; the amplitude of the shorter correlation time is greater than for the DANZ conjugate. At 9, 25, and 40°C in the presence of Ca 2+ , and at 9°C in its absence, the magnitude of the long correlation time is consistent with motion of the entire molecule; at higher temperatures in the absence of Ca 2+ it is substantially smaller, suggesting the presence of internal rotation. For Ca 2+ ‐liganded TnC at temperatures of 25°C or lower, the results with all three labels are interpretable in terms of the crystallographic structure of TnC.