Size Evolution and Composition of the Intermediate Phase During Nonclassical Protein Crystal Growth from Solution

<div>We propose here that the intermediate nucleation phase identified in a certain case</div><div>of protein crystal growth actually consists of two distinct parts; a low density and</div><div>higher density phase. A theory for crystal growth is utilized to study the formation</div><div>and growth of each phase. Within the framework of this theory the low density phase</div><div>is shown to obey a forth order kinetic law while the high density phase is zeroth order.</div><div>The combination of these two phases is shown to be a good match for X-ray diffraction </div><div>data which is indicative of its presence. The crystal growth rate is then given</div><div>in terms of the kinetic behavior of the intermediate nucleation phase. From this, the</div><div>crystal radius is estimated and shown to compare favorably with reported size data.</div><div>A method is proposed for determining the conditions that lead to protein crystals of</div><div>largest possible size.</div>