Crystal structure of hen egg-white lysozyme at a hydrostatic pressure of 1000 atmospheres.

摘要: Abstract The crystal structure of tetragonal hen egg-white lysozyme at a hydrostatic pressure 1000 atmospheres has been determined by X-ray diffraction to nominal resolution 2 A. crystals, originally grown in 0.83 m -NaCl, had be transferred 1.4 -NaCl prevent cracking 300 400 atm. and b axes the unit cell contracted 0.6%, whilst c axis increased 0.1%. volume 1.1%. Both 1 atm structures were refined restrained least-squares yield final R factors 14.9% each case. Since data collected an accurate difference protocol, change is considered more than absolute structure. probable accuracy atomic shifts shown ±0.06 estimated decrease whole molecule corresponded isothermal compressibility 4.7 × 10 −3 kbar −1 . contraction was non-uniformly distributed. Domain (residues 40 88) essentially incompressible, domain 39, 89 129) 5.7 interdomain region also compressible. average B factor decreased about A atm, but there wide range decreases increases individual values. pressure-induced deformation analyzed with distance matrices. beta-sheet 42 60) helix 24 36) deformed least under pressure. other helices one loop 61 87) actually appeared expand. main-chain atoms used perform superposition models. root-mean-square shift for all 0.2 A, few moving There no evidence co-ordinated movement hinge defined alpha carbon 38 97. included 151 163 ordered water molecules, respectively. changes these molecules mean solvent will described elsewhere.