The influence of proteins on the esterase activity of bile-salt-stimulated lipase from human milk
O'Connor, C.J.; Walde, P.
New Zealand Medical Journal 98(774): 158-159
1985
ISSN/ISBN: 0028-8446 PMID: 3856177 Document Number: 264601
Esterase activity of human milk lipase was assessed from hydrolysis of 4-nitrophenylacetate in the presence and absence of sodium taurocholate and various proteins. In the absence of taurocholate, human milk lysozyme had no effect on esterase activity, horse heart myoglobin was catalytic, and all other proteins (human milk lactoferrin, alpha -lactalbumin and immunoglobulin A, chicken egg white lysozyme, bee venom melittin and porcine pancreatic lipase) were inhibitory. In the presence of bile salt, lactoferrin and porcine pancreatic lipase were slightly inhibitory, chicken egg white lysozyme was slightly catalytic and the other proteins had no effect. It is concluded that proteins in human milk may stabilize the digestive process of human milk lipase until the milk reaches the duodenum, where bile salts stimulate activity and make inhibitory proteins ineffective.