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PDBsum entry 2iux
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References listed in PDB file
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Key reference
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Title
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Structure of testis ace glycosylation mutants and evidence for conserved domain movement.
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Authors
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J.M.Watermeyer,
B.T.Sewell,
S.L.Schwager,
R.Natesh,
H.R.Corradi,
K.R.Acharya,
E.D.Sturrock.
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Ref.
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Biochemistry, 2006,
45,
12654-12663.
[DOI no: ]
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PubMed id
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Abstract
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Human angiotensin-converting enzyme is an important drug target for which little
structural information has been available until recent years. The slow progress
in obtaining a crystal structure was due to the problem of surface
glycosylation, a difficulty that has thus far been overcome by the use of a
glucosidase-1 inhibitor in the tissue culture medium. However, the prohibitive
cost of these inhibitors and incomplete glucosidase inhibition makes alternative
routes to minimizing the N-glycan heterogeneity desirable. Here, glycosylation
in the testis isoform (tACE) has been reduced by Asn-Gln point mutations at
N-glycosylation sites, and the crystal structures of mutants having two and four
intact sites have been solved to 2.0 A and 2.8 A, respectively. Both mutants
show close structural identity with the wild-type. A hinge mechanism is proposed
for substrate entry into the active cleft, based on homology to human ACE2 at
the levels of sequence and flexibility. This is supported by normal-mode
analysis that reveals intrinsic flexibility about the active site of tACE.
Subdomain II, containing bound chloride and zinc ions, is found to have greater
stability than subdomain I in the structures of three ACE homologues.
Crystallizable glycosylation mutants open up new possibilities for
cocrystallization studies to aid the design of novel ACE inhibitors.
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