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Title
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Structure of bacteriophage T4 lysozyme refined at 1.7 A resolution.
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Authors
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L.H.Weaver,
B.W.Matthews.
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Ref.
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J Mol Biol, 1987,
193,
189-199.
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PubMed id
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Abstract
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The structure of the lysozyme from bacteriophage T4 has been refined at 1.7 A
resolution to a crystallographic residual of 19.3%. The final model has bond
lengths and bond angles that differ from "ideal" values by 0.019 A and 2.7
degrees, respectively. The crystals are grown from electron-dense phosphate
solutions and the use of an appropriate solvent continuum substantially improved
the agreement between the observed and calculated structure factors at low
resolution. Apart from changes in the conformations of some side-chains, the
refinement confirms the structure of the molecule as initially derived from a
2.4 A resolution electron density map. There are 118 well-ordered solvent
molecules that are associated with the T4 lysozyme molecule in the crystal. Four
of these are more-or-less buried. There is a clustering of water molecules
within the active site cleft but, other than this, the solvent molecules are
dispersed around the surface of the molecule and do not aggregate into ice-like
structures or pentagonal or hexagonal clusters. The apparent motion of T4
lysozyme in the crystal can be interpreted in terms of significant interdomain
motion corresponding to an opening and closing of the active site cleft. For the
amino-terminal domain the motion can be described equally well (correlation
coefficients approx. 0.87) as quasi-rigid-body motion either about a point or
about an axis of rotation. The motion in the crystals of the carboxy-terminal
domain is best described as rotation about an axis (correlation coefficient
0.80) although in this case the apparent motion seems to be influenced in part
by crystal contacts and may be of questionable relevance to dynamics in solution.
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