Premium
DEMONSTRATION THAT PHOSPHORESCENT 6‐BROMO‐2‐NAPHTHYL SULFATE CAN BE USED TO PROBE HEME ACCESSIBILITY IN HEME PROTEINS
Author(s) -
Bayles Stephen W.,
Beckham Suzy,
Leidig Paige R.,
Montrem Anne,
Taylor Mervin L.,
Wright Tony M.,
WU Ying,
Schuh Merlyn D.
Publication year - 1991
Publication title -
photochemistry and photobiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.818
H-Index - 131
eISSN - 1751-1097
pISSN - 0031-8655
DOI - 10.1111/j.1751-1097.1991.tb02004.x
Subject(s) - phosphorescence , chemistry , quenching (fluorescence) , photochemistry , heme , myoglobin , protoporphyrin , hemeprotein , fluorescence , aqueous solution , porphyrin , organic chemistry , physics , quantum mechanics , enzyme
The phosphorescence properties of 6‐bromo‐2‐naphthyl sulfate (BNS) in aqueous solution were studied. The phosphorescence lifetime is several hundred us and is self‐quenched. Although a fluorescent photoproduct is formed from BNS, it does not interfere with the decay properties of triplet‐state BNS and its utility as a probe of the accessibility of the heme group in heme proteins. Quenching of BNS phosphorescence does not occur for the non‐heme protein lysozyme and apomyoglobin but occurs by a dynamic mechanism with a quenching constant of1–2 × 10 9 M −1 s −1 for cytochrome c and myoglobin and with a quenching constant of 6.2 × 10 9 M −1 s −1 for protoporphyrin IX. The phosphorescence of an inclusion complex of 1‐bromonaphthalene and β‐cyclodextrin is not quenched by heme‐containing proteins. The temperature and viscosity dependencies of the rate with which BNS phosphorescence is quenched by microperoxidase‐11 are consistent with unit quenching efficiency. These results indicate that quenching of BNS phosphorescence occurs only upon contact with the quencher, and the quenching constant can be used to assess the degree of accessibility of the heme group.