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Structure—function analysis of the α5 and the α13 helices of human glucokinase: Description of two novel activating mutations
Author(s) -
Pedelini Leda,
GarciaGimeno Maria Adelaida,
Marina Alberto,
GomezZumaquero Juan M.,
RodriguezBada Pablo,
LópezEnriquez Soledad,
Soriguer Federico C.,
CuestaMuñoz Antonio L.,
Sanz Pascual
Publication year - 2005
Publication title -
protein science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.353
H-Index - 175
eISSN - 1469-896X
pISSN - 0961-8368
DOI - 10.1110/ps.051485205
Subject(s) - glucokinase , function (biology) , mutation , computational biology , chemistry , genetics , biology , gene
It was recently described that the α5 and the α13 helices of human pancreatic glucokinase play a major role in the allosteric regulation of the enzyme. In order to understand the structural importance of these helices, we have performed site‐directed mutagenesis to generate glucokinase derivatives with altered residues. We have analyzed the kinetic parameters of these mutated forms and compared them with wild‐type and previously defined activating mutations in these helices (A456V and Y214C). We found two new activating mutations, A460R and Y215A, which increase the affinity of the enzyme for glucose. Our results suggest that substitutions in the α5 or the α13 helices that favor the closed, active conformation of the enzyme, either by improving the interaction with surrounding residues or by improving the flexibility of the region defined by these two helices, enhance the affinity of the enzyme for glucose, and therefore its performance as a glucose phosphorylating enzyme.