Array, soaking solutions and method of selecting soaking conditions for small molecules in biological macromolecular crystals

A method of selecting the composition of a soaking solution for soaking the crystal form of a biological macromolecule wherein the soaking solution comprises an organic solvent (os), a compatible solute (cs), and a crystallization solution (crs) and/or water (w);

• said method comprising;
• 1) preparing a first series of in to xn individual soaking solutions by mixing os, cs, crs and w wherein:
• a) x is at least 2
• b) each soaking solutions of the first series comprises the same organic solvent (os), the same compatible solute (cs), and the same crystallization solution (crs), and
• c) Vos and Vcs are the same in each solution, or, alternatively, the number of moles compatible solute Ncs per volume organic solvent Vos is the same in each solution, and
• d) Vcrs and Vw are changed in each solution, and
• in the solution in, Vcrs is the minimum Vcrs (Vcrs min) and the Vw is the maximum Vw (Vwmax), and
• in the solution xn, Vw is the minimum Vw (Vwmin) and the Vcrs is the maximum Vcrs(Vcrs max), and
• when x>2, in any additional solutions between in and xn, the Vcrs is varied between Vcrs min and Vcrs max and, inversely, Vw is varied between Vwmin and Vwmax
• 2) transferring at least one crystal of the biological macromolecular crystal per compartment into x compartments, each compartment comprising one of the solutions prepared in step 1);
• or transferring each solution prepared in step 1) into x compartments, each compartment comprising at least one crystal of the biological macromolecular crystal from its crystallization solution.
• 3) controlling the crystal in each compartment
• 4) selecting the soaking solution(s) which is/are suitable for soaking the crystal;
• and
• wherein the compatible solute is selected from polyols, amino acids, methylamines, and mixtures thereof, and
• wherein the organic solvent is selected from liquid carbohydrates, protic or aprotic, of low reactivity, that can serve to solve small molecules and, mixtures thereof, and wherein the crystallization solution crs is obtained from the crystallization process of said crystal or is equivalent thereto in terms of osmotic net pressure, permittivity, solubility of the according biological macromolecule, and effect on its structural conformation, comprising pH and buffer materials, additives, and precipitants.