Structural features of bovine caseinomacropeptide A and B by 1H nuclear magnetic resonance spectroscopy.
Samples of bovine caseinomacropeptide (CMP) were isolated from kappa-casein A and kappa-casein B and fractionated to give aglycosylated CMP A and CMP B and monoglycosylated CMP A. The secondary structures of these three peptides were compared under neutral and acidic (pH 4.2) conditions, using two-dimensional (2D) 1H nuclear magnetic resonance (NMR) spectroscopy. The differences between the spectra at pH 4.2 and 7.0 and the spectra of the aglycosylated and glycosylated CMP A were subtle, indicating little change in backbone conformation with these changes. These results Suggest that differences in the coagulation properties of milks containing either kappa-casein A or kappa-casein B are more likely to be related to factors, such as micelle size or charge, than to structural differences arising from altered backbone conformation of the macropeptide segments of the kappa-caseins.
Smith
Mark H
MH
Food Science Section, New Zealand Dairy Research Institute, Palmerston North, New Zealand.
Edwards
Patrick J B
PJ
Palmano
Kate P
KP
Creamer
Lawrence K
LK
D000465:Algorithms; D000595:Amino Acid Sequence; D000818:Animals; D002364:Caseins / Q000032:analysis / Q000737:chemistry*; D002417:Cattle; D006031:Glycosylation; D006863:Hydrogen-Ion Concentration; D009682:Magnetic Resonance Spectroscopy / Q000379:methods*; D008823:Micelles; D008894:Milk Proteins / Q000032:analysis; D008968:Molecular Conformation; D008969:Molecular Sequence Data; D010316:Particle Size; D010446:Peptide Fragments / Q000032:analysis / Q000737:chemistry*; D017433:Protein Structure, Secondary
D002364:Caseins; D008823:Micelles; D008894:Milk Proteins; D010446:Peptide Fragments; C065989:caseinomacropeptide