Structural transformations in protein crystals caused by controlled dehydration.
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Date
1985-08
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Abstract
Recent experiments in this laboratory on structural transformations caused by
controlled dehydration of protein crystals have been reviewed. X-ray diffraction patterns of the
following crystals have been examined under varying conditions of environmental humidity in
the relative humidity range of 100–75 %: a new crystal form of bovine pancreatic ribonuclease
A grown from acetone solution in tris buffer (I), the well-known monoclinic form of the
protein grown from aqueous ethanol (II), the same form grown from a solution of 2-methyl
pentan-2,4-diol in phosphate buffer (III), tetragonal (IV), orthorhombic (V), monoclinic
(VI) and triclinic (VII) hen egg white lysozyme, porcine 2 Zn insulin (VIII), porcine 4 Zn
insulin (IX) and the crystals of concanavalin A(X). I, II, IV, V and VI undergo one or more
transformations as evidenced by discontinuous changes in the unit cell dimensions, the
diffraction pattern and the solvent content. Such water-mediated transformations do not
appear to occur in the remaining crystals in the relative humidity range explored. The relative
humidity at which the transformation occurs is reduced when 2-methyl pentan-2,4-diol is
present in the mother liquor. The transformations are affected by the crystal structure but not
by the amount of solvent in the crystals. The X-ray investigations reviewed here and other
related investigations emphasize the probable importance of water-mediated transformations
in exploring hydration of proteins and conformational transitions in them.
Description
Keywords
Water-mediated transformations, environmental humidity, protein crystals, conconf ormational, protein hydration
Citation
D M Salunke, Veerapandian B, Kodandapani R, Vijayan M. Structural transformations in protein crystals caused by controlled dehydration. Journal of Biosciences. 1985 Aug; 8(1&2): 37-44.