Protein melting point - Case study

Many proteins show profound changes when exposed to solution conditions, with the most extreme structure change being thermal denaturation. When a protein is heated above its characteristic thermal stability point (protein melting point), significant unfolding leads to exposed hydrophobic chains and can cause severe, nonreversible aggregation.

Light scattering is ideal for studying melting point protein characterization phenomenon as the technique is exquisitely sensitive to large scattering objects such as aggregates and denatured protein. Similar structure changes may happen over time, pH, ionic strength and changes in various other solution conditions, and light scattering again is an ideal tool to quickly assess the condition of the molecule in solution.

	Presentations:
	On demand presentation on Melting Point Protein Characterization. Proteins are charged biomolecules that can fold into compact structures that are very sensitive to solution conditions. As an extreme case, thermal denaturation can lead to irreversible loss of structure and function of the molecule. Thermal denaturation typically leads to an increase in size that can be monitored by dynamic light scattering. At the protein melting point, a marked increase in hydrodynamic size and scattering intensity is observed. This protein melting point temperature is indicative of the thermal stability of a protein. Modifications (such as glycosylation) can influence the stability and are easily observed using dynamic light scattering.
	Application note on Melting Point Protein Characterization. Proteins are composed of polypeptide chains with unique 3-dimensional structures in the native state. These structures are stabilized by a combination of electrostatic and hydrophobic interactions, combined with a large degree of flexibility inside the structure of the molecule. If solution conditions change, denaturation or unfolding can quickly occur, along with a subsequent change in size. The sensitivity of dynamic light scattering is ideally suited for monitoring the stability of a protein to denaturing conditions. The protein melting point temperature is indicative of the thermal stability of a protein. Modifications (such as glycosylation) can influence the stability and are easily observed with dynamic light scattering.
	Application note on a Therapeutic Protein Characterization. Proteins consist of polypeptide chains that are sensitive to various treatment conditions such as preparation, storage, buffer, etc. This application note describes dynamic and static light scattering characterization of a therapeutic antibody supplied in two forms: an untreated and a treated preparation. Information about the treatment process was not divulged. Hydrodynamic size, molecular weight and melting point of the two samples are compared. The absence of a melting point in the treated sample seems to suggest that the treatment process was similar in effect to thermal denaturation.