Proteomic profiling of the coagulation of milk proteins induced by chymosin.
Chymosin-induced coagulation of individual milk proteins during incubation at 30 °C was investigated using a proteomic approach. The addition of chymosin (0.006 units/mL) caused the milk proteins to coagulate after a 3 h incubation period. Approximately 88% of the milk proteins were coagulated into the milk pellet fraction, and the protein concentration of the milk supernatant fraction (MSF) decreased from 29.88 ± 0.12 to 3.74 ± 0.13 mg/mL. SDS-PAGE analysis showed that α(S)-, β- and κ-caseins in the MSF were almost depleted and that the total intensity of the protein bands corresponding to α(S)-caseins (α(S1) and α(S2)), β-casein, and κ-casein decreased from 1088.0, 901.5, and 617.0 area units to 6.9, 6.1, and 5.2 area units, respectively. Two-dimensional electrophoresis analysis indicated that α(S1)-, α(S2)-, β-, and κ-casein and a fraction of the β-lactoglobulin and serum albumin were found in the MSF following incubation with chymosin.
Department of Food Science, Fu Jen Catholic University, Taipei 242, Taiwan. 075101@mail.fju.edu.tw
Jung-Feng
JF
Hsieh
Pei-Hsin
PH
Pan
D000818:Animals; D017849:Animals, Inbred Strains; D002417:Cattle; D012085:Chymosin / Q000378:metabolism*; D015180:Electrophoresis, Gel, Two-Dimensional; D005260:Female; D008894:Milk Proteins / Q000737:chemistry* / Q000378:metabolism*; D010446:Peptide Fragments / Q000737:chemistry* / Q000378:metabolism*; D010449:Peptide Mapping; D011489:Protein Denaturation; D040901:Proteomics / Q000379:methods
D008894:Milk Proteins; D010446:Peptide Fragments; D012085:Chymosin