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PDBsum entry 4l5u
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References listed in PDB file
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Key reference
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Title
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Structural, Catalytic and stabilizing consequences of aromatic cluster variants in human carbonic anhydrase ii.
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Authors
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C.D.Boone,
S.Gill,
C.Tu,
D.N.Silverman,
R.Mckenna.
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Ref.
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Arch Biochem Biophys, 2013,
539,
31-37.
[DOI no: ]
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PubMed id
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Abstract
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The presence of aromatic clusters has been found to be an integral feature of
many proteins isolated from thermophilic microorganisms. Residues found in
aromatic cluster interact via π-π or C-H⋯π bonds between the phenyl rings,
which are among the weakest interactions involved in protein stability. The lone
aromatic cluster in human carbonic anhydrase II (HCA II) is centered on F226
with the surrounding aromatics F66, F95 and W97 located 12 Å posterior the
active site; a location which could facilitate proper protein folding and active
site construction. The role of F226 in the structure, catalytic activity and
thermostability of HCA II was investigated via site-directed mutagenesis of
three variants (F226I/L/W) into this position. The measured catalytic rates of
the F226 variants via (18)O-mass spectrometry were identical to the native
enzyme, but differential scanning calorimetry studies revealed a 3-4 K decrease
in their denaturing temperature. X-ray crystallographic analysis suggests that
the structural basis of this destabilization is via disruption and/or removal of
weak C-H⋯π interactions between F226 to F66, F95 and W97. This study
emphasizes the importance of the delicate arrangement of these weak interactions
among aromatic clusters in overall protein stability.
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