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Bile salt‐stimulated lipase in human milk: Evidence for its synthesis in the lactating mammary gland
Author(s) -
Bläckberg Lars,
Ängquist Karl-Axel,
Hemell Olle
Publication year - 1987
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/0014-5793(87)81237-1
Subject(s) - mammary gland , lipase , enzyme , biochemistry , methionine , chemistry , breast milk , biology , medicine , endocrinology , amino acid , cancer , breast cancer
Human milk contains many enzymes and other biologically active proteins. One of the enzymes, the bile salt‐stimulated lipase, constitutes as much as 1% of the milk proteins. Its importance for efficient utilization of milk lipids by the breast‐fed infant is now well established. However, whether the lipase protein is a product of protein synthesis within the mammary gland has up till now been an unanswered question. Using biopsy material from lactating human mammary gland we have now demonstrated that the enzyme is synthesized within the gland. This was done by immunoprecipitation of [ 35 S]methionine‐labelled protein from tissue pieces. By activity determination we could also determine the amount of enzyme stored in the gland. It was concluded that bile salt‐stimulated lipase accounted for 1.3 μg/mg tissue protein. Finally, from this figure it could be calculated that about 10–15% of the total protein present in the tissue was milk protein.