Limited proteolysis of beta-lactoglobulin using thermolysin. Effects of calcium on the outcome of proteolysis.
Bovine beta-lactoglobulin variant B was hydrolysed with thermolysin at various concentrations of calcium ions ranging between 0 and 50 mM. The changes in calcium concentration did not influence the overall rates of beta-lactoglobulin proteolysis. However, HPLC analyses of the hydrolysates, obtained at nine different calcium concentrations, indicated that the rates of production and/or lysis of 3 of 17 identified peptides were calcium concentration-dependent. Proteolysis at low calcium concentrations yielded peptides V41-E45 and V43-L57. The peptide V43-L57, containing a cluster of dicarboxylic amino acids, was resistant to further hydrolysis by thermolysin even after 10 h incubation. An increase in calcium concentration triggered gradual hydrolysis of this peptide. Its hydrolytic product (peptide V43-D53) was obtained only by proteolysis of beta-lactoglobulin with thermolysin at high calcium concentration.
Dufour
E
E
LEIMA-Institut National de la Recherche Agronomique, Nantes, France.
Dalgalarrondo
M
M
Haertlé
T
T
D000595:Amino Acid Sequence; D000818:Animals; D001665:Binding Sites; D002118:Calcium / Q000378:metabolism*; D002417:Cattle; D005260:Female; D014644:Genetic Variation; D006868:Hydrolysis; D066298:In Vitro Techniques; D007700:Kinetics; D007782:Lactoglobulins / Q000235:genetics / Q000378:metabolism*; D008969:Molecular Sequence Data; D010446:Peptide Fragments / Q000235:genetics / Q000378:metabolism; D013820:Thermolysin / Q000378:metabolism*
D007782:Lactoglobulins; D010446:Peptide Fragments; D013820:Thermolysin; D002118:Calcium