Norihiro Azuma

Identification of α-lactalbumin and β-lactoglobulin in cynomolgus monkey (Macaca fascicularis) milk

1. n1. An electrophoretic analysis of whey protein from cynomolgus monkey milk revealed that its consituents are more similar to bovine milk than human milk, i.e. cynomolgus monkey milk whey contains, besides α-lactalbumin-like protein (LaP), another predominant component similar to bovine β-lactoglobulin (LgP), in its electrophoretic behavior on both disc- and SDS-polyacrylamide gel electrophoreses. n n2. n2. The amino acid composition of LaP shows close similarity to that of human α-lactalbumin, and LaP forms an immunoprecipitin line with anti-human α-lactalbumin rabbit antiserum. The homology between LaP and α-lactalbumin was further confirmed by an alaysis of the N-terminal amino acid sequence. n n3. n3. LgP is not immunologically identical to bovine β-lactoglobulin, but its amino acid composition is similar. The result of the N-terminal amino acid seuence analysis of LgP (up to the 26th residue) strongly suggests homology between this protein and β-lactoglobulin.

A glyco-phosphoprotein in human milk

A highly glycosylated phosphoprotein (HGPP) was isolated from a human casein fraction by reversed-phase high-performance liquid chromatography. This component contained carbohydrates to approximately 38.2% (w/w) and phosphorus to approximately 1.6% (w/w). The molecular weight of this HGPP as estimated by sodium dodecyl sulphate-polyacrylamide gel electrophoresis approximately 41,000. Ultracentrifugal analysis revealed that the sedimentation coefficient of the HGPP was 2.6S in a buffer at pH 7.0 and 27 degrees C, but this component interacted with human k-casein and formed a complex with s = 10.4S.

Comparison of casein of cynomolgus monkey (Macaca fascicularis) with human casein

Casein of cynomolgus monkey was compared with those from human and bovine milk. Cynomolgus monkey casein showed similar electrophoretical patterns to those of human casein on Disc- and SDS-electrophoresis. It consisted of beta- and kappa-casein-like components. The component corresponding to bovine alpha s1-casein was not detected. The beta-casein-like fraction of cynomolgus monkey showed 9 bands on Disc-PAGE. These were suggested to be the same protein binding different levels of phosphorus by dephosphorylation experiment using an acid phosphatase. The kappa-casein-like component of cynomolgus monkey was highly glycosylated (about 50% carbohydrate) similarly as human kappa-casein and the constituent carbohydrates were same as those detected in human kappa-casein (galactose, fucose, N-acetylgalactosamine, N-acetylglucosamine, and sialic acid). Amino acid composition of cynomolgus monkey kappa-casein bore a resemblance to those of both human and bovine kappa-caseins. Amino acid composition of cynomolgus monkey beta-casein was also similar to those of human and bovine beta-caseins.