Selective Proteolysis of α-Lactalbumin by Endogenous Enzymes of Human Milk at Acidic pH.
Mol Nutr Food Res
; 63(18): e1900259, 2019 09.
Article
em En
| MEDLINE
| ID: mdl-31271254
ABSTRACT
SCOPE The use of human milk products is increasing for high-risk infants. Human milk contains endogenous enzymes that comprise a dynamic proteolytic system, yet biological properties of these enzymes and their activities in response to variations including pH within infants are unclear. Human milk has a neutral pH around 7, while infant gastric pH varies from 2 to 6 depending on individual conditions. This study is designed to determine the specificity of enzyme-substrate interactions in human milk as a function of pH. METHODS AND RESULTS:
Endogenous proteolysis is characterized by incubating freshly expressed human milk at physiologically relevant pH ranging from 2 to 7 without the addition of exogenous enzymes. Results show that the effects of pH on endogenous proteolysis in human milk are protein-specific. Further, specific interactions between cathepsin D and α-lactalbumin are confirmed. The endogenous enzyme cathepsin D in human milk cleaves α-lactalbumin as the milk pH shifts from 7 to 3.CONCLUSIONS:
This study documents that selective proteolysis activated by pH shift is a mechanism for dynamic interactions between human milk and the infant. Controlled proteolysis can guide the use of human milk products based on individual circumstance.Palavras-chave
Texto completo:
1
Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Lactalbumina
/
Leite Humano
/
Proteínas do Leite
Limite:
Humans
Idioma:
En
Ano de publicação:
2019
Tipo de documento:
Article