Alpha-Lactalbumin and lactose concentrations in rat milk during lactation.
Homogeneous rat alpha-lactalbumin was prepared from whey by chromatography on DEAE-Sephadex A-50 and Ultrogel AcA 44. Two biologically active forms of alpha-lactalbumin were apparent after ion-exchange chromatography, but on gel filtration the combined forms were eluted as a single peak with a molecular weight of approx. 33000. The molecular weight when determined by sodium dodecyl sulphate/polyacrylamide-gel electrophoresis was 15100. Antiserum to alpha-lactalbumin was prepared from rabbits, and single radial immunodiffusion was used to measure the concentration of alpha-lactalbumin in milk expressed from rats during lactation and for 2 days after the cessation of lactation. A significant positive correlation (r = + 0.89) between the concentrations of alpha-lactalbumin and lactose was obtained for the first 20 days of lactation. This is consistent with the suggestion that alpha-lactalbumin may control the concentration of lactose in milk. However, a significant negative correlation (r = -0.91) between the concentration of alpha-lactalbumin and lactose was obtained for 2 days after the cessation of lactation on day 20.
D000818:Animals; D002852:Chromatography, Ion Exchange; D004591:Electrophoresis, Polyacrylamide Gel; D005260:Female; D007768:Lactalbumin / Q000302:isolation & purification / Q000378:metabolism*; D007774:Lactation; D007785:Lactose / Q000378:metabolism*; D008892:Milk / Q000378:metabolism*; D008970:Molecular Weight; D011247:Pregnancy; D051381:Rats
D007768:Lactalbumin; D007785:Lactose