MATRIX COPRECIPITATING AND COCRYSTALLIZING LIGANDS (MCC LIGANDS) FOR BIOSEPARATIONS

Instead of trying to crystallize or precipitate amino acids and proteins as homogeneous products, often it is easier to coprecipitate or to cocrystallize them. Organic ionic ligands with large apolar groups bind to the solute or compound sought to isolate. The resulting complexes come out of solution as coprecipitates, often as cocrystals. Binding isotherms, Job plot analysis, compositional and calorimetric data give combining stoichiometries for matrix ligands to amino acids, dipeptides and proteins. These are 1 : 1 or 2 : 1, for amino acids and dipeptides, in cocrystalline complexes. Coprecipitates of lysozyme and alpha-chymotrypsin bind anionic ligands strongly in combining ratios very close to protein net proton charge.