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The measurement of transmembrane helices by the deconvolution of CD spectra of membrane proteins: A review
Author(s) -
Fasman Gerald D.
Publication year - 1995
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.360370505
Subject(s) - chemistry , deconvolution , helix (gastropod) , protein secondary structure , transmembrane domain , spectral line , crystallography , transmembrane protein , membrane , analytical chemistry (journal) , physics , optics , ecology , biochemistry , receptor , chromatography , astronomy , snail , biology
The interpretation of the CD spectra of proteins to date requires additional secondary structural information of the proteins to be analyzed, such as x‐ray or nmr data. Therefore, these methods are inappropriate for a CD data base whose secondary structures are unknown, as in the case of the membrane proteins. The Convex Constraint Analysis algorithm [A. Perczel, M. Hollósi, G. Tusnády, and G. D. Fasman (1991) Protein Engineering, Vol. 4, 669–679], on the other hand, operates only on a collection of spectral data to extract the common spectral components with their spectral weights. The linear combinations of these derived “pure” CD curves can reconstruct the original data set with great accuracy. For a membrane protein data set, the five‐component spectra so obtained from the deconvolution consisted of two different types of α‐helices (the α‐helix in the soluble domain and the α T ‐helix, for the transmembrane α‐helix), a β‐pleated sheet, a class C‐like spectrum related to β‐turns, and a spectrum correlated with the unordered conformation. The deconvoluted CD spectrum for the α T ‐helix was characterized by a positive red‐shifted band in the range 195–200 nm (+95,000 deg cm 2 dmol −l ), with the intensity of the negative band at 208 nm being slightly less negative than that of the 222 nm band (−50,000 and −60,000 deg cm 2 dmol −1 , respectively) in comparison with the regular α‐helix, with a positive band at 190 nm and two negative bands at 208 and 222 nm with magnitudes of + 70,000, −30,000, and −30,000 deg cm 2 dmol −1 , respectively. © 1994 John Wiley & Sons, Inc.