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Three‐dimensional structure of actinoxanthin. III. A 4‐Å resolution
Author(s) -
Pletnev V. Z.,
Kuzin A. P.,
Trakhanov S. D.,
Kostetsky P. V.,
Popovich V. A.,
Tsigannik I. N.
Publication year - 1981
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.1981.360200405
Subject(s) - chemistry , crystallography , resolution (logic) , disulfide bond , unit (ring theory) , molecule , ellipsoid , chain (unit) , oblate spheroid , group (periodic table) , phase (matter) , physics , mathematics , atomic physics , organic chemistry , biochemistry , mathematics education , artificial intelligence , computer science , astronomy
The protein actinoxanthin (molecular weight 10,300) crystallizes in space group P 2 1 2 1 2 1 , with cell dimensions a = 30.9 Å, b = 48.8 Å, c = 64.1 Å, and z = 4. The three‐dimensional structure of actinoxanthin at 4‐Å resolution was determined by x‐ray methods on the basis of experimental data from the native protein and five isomorphous derivatives. At the stage of solving the phase problem, the heavy atoms in the derivatives were located using direct methods. The actinoxanthin molecule can be described as an oblate ellipsoid with approximate dimensions 20 × 30 × 40 Å and consists of two different sizes of folded units separated by a well‐defined cleft. The larger unit, including the N‐ and C‐terminals of the protein chain, is characterized by a significant content of β‐sheet structure. The smaller unit, containing two deca‐ and hexapeptide cycles closed by disulfide bonds, has a mainly irregular structure.