ABSTRACT
Proteins are defined as sequence-specific polymers of Lα amino acids linked by peptide bonds. Reactions of proteins are studied as precipitation reactions and color reactions. Proteins are large molecules with variable sizes, shapes, and charges. Protein solubility depends on the distribution of polar hydrophilic groups and nonpolar hydrophobic groups in the molecule. The stability of a protein in a solution will depend mainly on the charge and the degree of hydration (shell of water molecules around the particles). Any factor that neutralizes the charge or removes the shell of hydration will cause precipitation of proteins. Precipitation is used to separate proteins from biological fluids such as blood, plasma, and CSF before the estimation of important chemical constituents such as urea, sugar, and creatinine, because proteins interfere in their estimation. The negatively charged ions of the alkaloids neutralize the positive charge on the protein causing denaturation, which results in precipitation.
