Alkaline solution, protein changes

Partial removal of the phosphate groups of phosvitin by -elimination in alkaline solution results in a decreased in vitro initial rate of hydrolysis by trypsin (268). The decreased rate of hydrolysis might be a result of (a) a change in conformation of the protein on removal of the phosphate groups, (b) cross-linking by the reaction of the dehydroalanine residues with lysine residues (to form lysinoalanine), or (c) racemization of some of the residues by the alkaline treatment. 

Other IRRAS applications to peptides and proteins. In addition to the pulmonary surfactant system, a variety of other applications employing IRRAS to study peptide and protein conformation and orientation have appeared. The secondary structure conversion of the amyloid (prion)-protein in the normal form into the abnormal form is the main cause of several human and animal diseases, such as Alzheimer s disease [68]. The secondary structure of the first 40 residues of the amyloid protein was detected by circular dichroism (CD) in aqueous solution and with IRRAS at the interface. A stable /1-sheet-enriched state of the amyloid is formed at the air-water interface, in contrast to the initial bulk solution containing high a-helix/random coil and low /l-sheet parts. The change in the pH going from bulk (alkaline pH) to the interface (neutral or slightly acidic pH) can have effects on the conformation at the interface. Another alternative might be the intrinsic hydrophobicity of the air-water interface, which is a hydrophobic-hydrophilic system with air as the hydrophobic part. 

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