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. 1994 May;3(5):838–842. doi: 10.1002/pro.5560030513

A conserved glutamic acid bridge in serine carboxypeptidases, belonging to the alpha/beta hydrolase fold, acts as a pH-dependent protein-stabilizing element.

U H Mortensen 1, K Breddam 1
PMCID: PMC2142726  PMID: 7914789

Abstract

Serine endopeptidases of the chymotrypsin family contain a salt bridge situated centrally within the active site, the acidic component of the salt bridge being adjacent to the catalytically essential serine. Serine carboxypeptidases also contain an acidic residue in this position but it interacts through a short hydrogen bond, probably of low-barrier type, with another acidic residue, hence forming a "glutamic acid bridge." In this study, the residues constituting this structural element in carboxypeptidase Y have been replaced by site-specific mutagenesis. It is demonstrated that the glutamic acid bridge contributes significantly to the stability of the enzyme below pH 6.5 and has an adverse effect at pH 9.5. Carboxypeptidase WII from wheat contains 2 such bridges, and it is more stable than carboxypeptidase Y at acidic pH.

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Selected References

These references are in PubMed. This may not be the complete list of references from this article.

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