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PDBsum entry 1aql
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Contents |
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* Residue conservation analysis
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References listed in PDB file
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Key reference
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Title
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The crystal structure of bovine bile salt activated lipase: insights into the bile salt activation mechanism.
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Authors
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X.Wang,
C.S.Wang,
J.Tang,
F.Dyda,
X.C.Zhang.
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Ref.
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Structure, 1997,
5,
1209-1218.
[DOI no: ]
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PubMed id
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Abstract
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BACKGROUND: The intestinally located pancreatic enzyme, bile salt activated
lipase (BAL), possesses unique activities for digesting different kinds of
lipids. It also differs from other lipases in a requirement of bile salts for
activity. A structure-based explanation for these unique properties has not been
reached so far due to the absence of a three-dimensional structure. RESULTS: The
crystal structures of bovine BAL and its complex with taurocholate have been
determined at 2.8 A resolution. The overall structure of BAL belongs to the
alpha/beta hydrolase fold family. Two bile salt binding sites were found in each
BAL molecule within the BAL-taurocholate complex structure. One of these sites
is located close to a hairpin loop near the active site. Upon the binding of
taurocholate, this loop becomes less mobile and assumes a different
conformation. The other bile salt binding site is located remote from the active
site. In both structures, BAL forms similar dimers with the active sites facing
each other. CONCLUSIONS: Bile salts activate BAL by binding to a relatively
short ten-residue loop near the active site, and stabilize the loop in an open
conformation. Presumably, this conformational change leads to the formation of
the substrate-binding site, as suggested from kinetic data. The BAL dimer
observed in the crystal structure may also play a functional role under
physiological conditions.
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Figure 2.
Figure 2. Stereo view of the structural comparison of
apo-BAL and GCL around their active sites. The Ca trace of the
apo-BAL structure is shown in magenta; the Ca trace of GCL is
shown in blue. Selected residues from BAL are labeled in red.
Also included are the catalytic triad residues from the two
structures, which are superimposed with each other.
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The above figure is
reprinted
by permission from Cell Press:
Structure
(1997,
5,
1209-1218)
copyright 1997.
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