An aminotransferase from Lactococcus lactis initiates conversion of amino acids to cheese flavor compounds.
Appl Environ Microbiol
; 63(2): 414-9, 1997 Feb.
Article
em En
| MEDLINE
| ID: mdl-9023921
ABSTRACT
The enzymatic degradation of amino acids in cheese is believed to generate aroma compounds and therefore to be involved in the complex process of cheese flavor development. In lactococci, transamination is the first step in the degradation of aromatic and branched-chain amino acids which are precursors of aroma compounds. Here, the major aromatic amino acid aminotransferase of a Lactococcus lactis subsp. cremoris strain was purified and characterized. The enzyme transaminates the aromatic amino acids, leucine, and methionine. It uses the ketoacids corresponding to these amino acids and alpha-ketoglutarate as amino group acceptors. In contrast to most bacterial aromatic aminotransferases, it does not act on aspartate and does not use oxaloacetate as second substrate. It is essential for the transformation of aromatic amino acids to flavor compounds. It is a pyridoxal 5'-phosphate-dependent enzyme and is composed of two identical subunits of 43.5 kDa. The activity of the enzyme is optimal between pH 6.5 and 8 and between 35 and 45 degrees C, but it is still active under cheese-ripening conditions.
Texto completo:
1
Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Queijo
/
Lactococcus lactis
/
Aromatizantes
/
Aminoácidos
/
Transaminases
Idioma:
En
Revista:
Appl Environ Microbiol
Ano de publicação:
1997
Tipo de documento:
Article
País de afiliação:
França