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Study of the Hydrophobic Cavity of β‐Cryptogein through Laser‐Polarized Xenon NMR Spectroscopy
Author(s) -
Berthault Patrick,
Huber Gaspard,
Ha Phuong Thu,
Dubois Lionel,
Desvaux Hervé,
Guittet Eric
Publication year - 2006
Publication title -
chembiochem
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.05
H-Index - 126
eISSN - 1439-7633
pISSN - 1439-4227
DOI - 10.1002/cbic.200500140
Subject(s) - xenon , proton , noble gas , spin diffusion , chemistry , isotopes of xenon , relaxation (psychology) , diffusion , spectroscopy , nuclear magnetic resonance spectroscopy , nuclear magnetic resonance , chemical physics , atomic physics , analytical chemistry (journal) , physics , stereochemistry , nuclear physics , thermodynamics , organic chemistry , psychology , social psychology , quantum mechanics
Abstract The interaction of xenon with β‐cryptogein, a basic 10 kDa protein belonging to the elicitin family, has been studied by using dissolved thermal and laser‐polarized gas in liquid‐state NMR. 13 C and 1 H chemical‐shift‐mapping experiments were unfruitful, the proton lines only experienced a slight narrowing but no significant frequency variation when the xenon concentration was increased. Nevertheless magnetization transfer from hyperpolarized xenon to protons of the protein demonstrates an undoubted interaction and enables localization of the noble‐gas‐binding site. Due to the proton–proton cross‐relaxation efficiency, however, this experiment is subjected to important spin‐diffusion. An automatic procedure that takes spin‐diffusion into account when assigning the protons that interact with xenon is then used. The binding site, as defined by 30 XeH interactions, is situated in the inner core of the protein. The protons that interact with xenon border the channel by which sterols are known to enter into the cavity. These results support the idea that xenon is a good probe for hydrophobic protein regions.