Bovine beta-lactoglobulin was hydrolyzed with trypsin or chymotrypsin in the course of heat treatment at 55, 60 and 65 degrees C at neutral pH. At these temperatures beta-lactoglobulin undergoes significant but reversible structural changes. In the conditions used in the present study, beta-lactoglobulin was virtually insensitive to proteolysis by either enzyme at room temperature, but underwent extensive proteolysis when either protease was present during the heat treatment. High-temperature proteolysis occurs in a progressive manner. Mass spectrometry analysis of some large-sized breakdown intermediates formed in the early steps of hydrolysis indicated that both enzymes effectively hydrolyzed some regions of beta-lactoglobulin that were transiently exposed during the physical treatments and that were not accessible in the native protein. The immunochemical properties of the products of beta-lactoglobulin hydrolysis were assessed by using various beta-lactoglobulin-specific antibodies, and most epitopic sites were no longer present after attack of the partially unfolded protein by the two proteases.
Proteolysis of bovine beta-lactoglobulin during thermal treatment in sub-denaturing conditions highlights some structural features of the temperature-modified protein and yields fragments with low immunoreactivity / S. Iametti, P. Rasmussen, H. Frøkiær, P. Ferranti, F. Addeo, F. Bonomi. - In: EUROPEAN JOURNAL OF BIOCHEMISTRY. - ISSN 0014-2956. - 269:5(2002), pp. 1362-1372.
Proteolysis of bovine beta-lactoglobulin during thermal treatment in sub-denaturing conditions highlights some structural features of the temperature-modified protein and yields fragments with low immunoreactivity
S. IamettiPrimo
;P. RasmussenSecondo
;F. BonomiUltimo
2002
Abstract
Bovine beta-lactoglobulin was hydrolyzed with trypsin or chymotrypsin in the course of heat treatment at 55, 60 and 65 degrees C at neutral pH. At these temperatures beta-lactoglobulin undergoes significant but reversible structural changes. In the conditions used in the present study, beta-lactoglobulin was virtually insensitive to proteolysis by either enzyme at room temperature, but underwent extensive proteolysis when either protease was present during the heat treatment. High-temperature proteolysis occurs in a progressive manner. Mass spectrometry analysis of some large-sized breakdown intermediates formed in the early steps of hydrolysis indicated that both enzymes effectively hydrolyzed some regions of beta-lactoglobulin that were transiently exposed during the physical treatments and that were not accessible in the native protein. The immunochemical properties of the products of beta-lactoglobulin hydrolysis were assessed by using various beta-lactoglobulin-specific antibodies, and most epitopic sites were no longer present after attack of the partially unfolded protein by the two proteases.Pubblicazioni consigliate
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