Discovery of halopyridines as quiescent affinity labels: inactivation of dimethylarginine dimethylaminohydrolase.
J Am Chem Soc
; 133(5): 1553-62, 2011 Feb 09.
Article
em En
| MEDLINE
| ID: mdl-21222447
ABSTRACT
In an effort to develop novel covalent modifiers of dimethylarginine dimethylaminohydrolase (DDAH) that are useful for biological applications, a set of "fragment"-sized inhibitors that were identified using a high-throughput screen are tested for time-dependent inhibition. One structural class of inactivators, 4-halopyridines, show time- and concentration-dependent inactivation of DDAH, and the inactivation mechanism of one example, 4-bromo-2-methylpyridine (1), is characterized in detail. The neutral form of halopyridines is not very reactive with excess glutathione. However, 1 readily reacts, with loss of its halide, in a selective, covalent, and irreversible manner with the active-site Cys249 of DDAH. This active-site Cys is not particularly reactive (pK(a) ca. 8.8), and 1 does not inactivate papain (Cys pK(a) ca. ≤4), suggesting that, unlike many reagents, Cys nucleophilicity is not a predominating factor in selectivity. Rather, binding and stabilization of the more reactive pyridinium form of the inactivator by a second moiety, Asp66, is required for facile reaction. This constraint imparts a unique selectivity profile to these inactivators. To our knowledge, halopyridines have not previously been reported as protein modifiers, and therefore they represent a first-in-class example of a novel type of quiescent affinity label.
Texto completo:
1
Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Piridinas
/
Marcadores de Afinidade
/
Inibidores Enzimáticos
/
Amidoidrolases
Tipo de estudo:
Prognostic_studies
Idioma:
En
Ano de publicação:
2011
Tipo de documento:
Article