ABSTRACT
Since the early 1970s, scientific advances in molecular biology and genetic engineering have led to enormous success in protein- and peptide-based therapeutics for the treatment of many human diseases. These cover almost all therapeutic categories, including cardiovascular hemostasis, antineoplastic, diabetes and endocrinology, anti-infective, neuropharmacological, enzyme replacement, wound healing, respiratory, and bone cartilage. Compared to small-molecule drugs, protein-based pharmaceuticals are not only larger in molecular weight but have a more complex higher order structures. Intrinsically, most proteins have poor thermodynamic and/or chemical stability and a short half-life in vivo. Majority of proteins require parenteral administration routes because of their poor oral bioavailability. Several analytical techniques can be used to characterize a protein’s size and soluble associative states. Routinely, electrophoretic and chromatographic techniques have been used to estimate protein size up to oligomers. Proteins contain both positively and negatively charged amino acids and are amphoteric molecules. One property that characterizes a protein’s charge profile is its isoelectric point or pI.
