Protein denaturation surface area

For denatured proteins (maximum surface area), A = 1.44MA2. 

We also noticed that the molecular area decreases gradually when the surface pressure is held at a certain value. Two possible explanations for this are (1) there may be some leakage of protein molecules from the surface into the subphase, since the protein is water soluble (2) protein denaturation may be taking place at the air-water interface. 

HIC, like IEC, is performed under conditions that preserve protein shape and activity. It is used in preparative applications to obtain a selectivity complimentary to IEC and akin to RPLC but without the denaturing properties of the latter technique. Although HIC and RPLC share a mechanism based on hydro-phobic partitioning, the actual peak spacing and elution order of the two techniques can be different. This arises from the different hydrophobic contact points presented by the protein under native (HIC) and denaturing (RPLC) conditions. Although not widely used for analytical separations, HIC can be used to answer questions about accessible hydrophobic surface area that cannot be addressed by RPLC.44... 

This phenomenon is known as surface denaturation. Adsorption area and, consequently, the extent of denaturation are decreased with an increasing specific adsorption of the anion. The dependence of the molecular weight versus adsorption area shows that the proteins of large molecular weight (above 15 kD) behave differently from the smaller proteins [94], as they possibly do not denaturate and spread on mercury to the same extent as... 

Despite some conflicting evidence (Kinsella and Fox, 1986), it appears that denaturation has little influence on the amount of water bound by whey proteins. However, other factors which may accompany denaturation (e.g. Maillard browning, association or aggregation of proteins) may alter protein sorption behaviour. Drying technique affects the water sorption characteristics of WPC. Freeze-dried and spray-dried WPC preparations bind more water at the monolayer level than do roller-, air- or vacuum-dried samples, apparently due to larger surface areas in the former. As discussed above, temperature also influences water sorption by whey protein preparations. The sorption isotherm for /Mactoglobulin is typical of many globular proteins. 

Because mD N is proportional to the number of groups in the protein, large proteins are more sensitive to solvent denaturation than small ones. It is a common mistake to attribute resistance to solvent denaturation of small proteins to high stability in fact, it is an inherent characteristic of a small change in surface area on denaturation. Also, proteins that are elongated have higher solvent exposure in the native state and correspondingly lower values of mD N. 

The change in both polar and apolar buried surface area on de-naturation can be estimated from the difference between the polar or apolar ASA of the folded protein and of the extended chain, respectively (Eisenberg and McLachlan, 1986 Ooi etal., 1987 Spolar et al., 1989). Although the denatured protein may not be a random coil, it has been argued that globular proteins behave experimentally... 

Denatured proteins are more asymmetric with a larger surface area than native proteins they are biologically inactive and may contain more titrable groups as buried groups are exposed to the environment. 

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