Crystallization, structure solution and refinement of hen egg-white lysozyme at pH 8.0 in the presence of MPD

Hen egg-white lysozyme has been crystallized at slightly alkaline pH using 2-methyl-2,4-pentanediol (MPD) as the precipitant. The crystals are nearly isomorphous to crystals grown at acidic pH using sodium chloride as the pre cipitant. However, the growth kinetics differ markedly between the two cond itions. The major reason for this is a molecule of MPD that binds tightly i n between two lysozyme molecules and favors the growth of the crystals alon g the crystallographic c direction over growth perpendicular to it.