Identification of alpha-lactalbumin and beta-lactoglobulin in cynomolgus monkey (Macaca fascicularis) milk.

1. An electrophoretic analysis of whey protein from cynomolgus monkey milk revealed that its constituents are more similar to bovine milk than human milk, i.e. cynomolgus monkey milk whey contains, besides alpha-lactalbumin-like protein (LaP), another predominant component similar to bovine beta-lactoglobulin (LgP), in its electrophoretic behavior on both disc- and SDS-polyacrylamide gel electrophoreses. 2. The amino acid composition of LaP shows close similarity to that of human alpha-lactalbumin, and LaP forms an immunoprecipitin line with anti-human alpha-lactalbumin rabbit antiserum. The homology between LaP and alpha-lactalbumin was further confirmed by an analysis of the N-terminal amino acid sequence. 3. LgP is not immunologically identical to bovine beta-lactoglobulin, but its amino acid composition is similar. The result of the N-terminal amino acid sequence analysis of LgP (up to the 26th residue) strongly suggests homology between this protein and beta-lactoglobulin.