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Visualizing the movement of the amphipathic helix in the respiratory complex I using a nitrile infrared probe and SEIRAS
Author(s) -
Santos Seica Ana Filipa,
Schimpf Johannes,
Friedrich Thorsten,
Hellwig Petra
Publication year - 2020
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1002/1873-3468.13620
Subject(s) - nitrile , infrared , amphiphile , infrared spectrophotometry , helix (gastropod) , movement (music) , chemistry , anatomy , medicine , biology , physics , optics , ecology , organic chemistry , acoustics , snail , copolymer , polymer , chromatography
Conformational movements play an important role in enzyme catalysis. Respiratory complex I, an L‐shaped enzyme, connects electron transfer from NADH to ubiquinone in its peripheral arm with proton translocation through its membrane arm by a coupling mechanism still under debate. The amphipathic helix across the membrane arm represents a unique structural feature. Here, we demonstrate a new way to study conformational changes by introducing a small and highly flexible nitrile infrared (IR) label to this helix to visualize movement with surface‐enhanced IR absorption spectroscopy. We find that labeled residues K551C L and Y590C L move to a more hydrophobic environment upon NADH reduction of the enzyme, likely as a response to the reorganization of the antiporter‐like subunits in the membrane arm.