4cla

<table><tr><td colspan='2'>[[4cla]] is a 1 chain structure with sequence from [http://en.wikipedia.org/wiki/"bacillus_coli"_migula_1895 "bacillus coli" migula 1895]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=4CLA OCA]. For a <b>guided tour on the structure components</b> use [http://oca.weizmann.ac.il/oca-docs/fgij/fg.htm?mol=4CLA FirstGlance]. <br>

</td></tr><tr id='ligand'><td class="sblockLbl"><b>[[Ligand|Ligands:]]</b></td><td class="sblockDat"><scene name='pdbligand=CLM:CHLORAMPHENICOL'>CLM</scene>, <scene name='pdbligand=CO:COBALT+(II)+ION'>CO</scene></td></tr>

<tr id='activity'><td class="sblockLbl"><b>Activity:</b></td><td class="sblockDat"><span class='plainlinks'>[http://en.wikipedia.org/wiki/Chloramphenicol_O-acetyltransferase Chloramphenicol O-acetyltransferase], with EC number [http://www.brenda-enzymes.info/php/result_flat.php4?ecno=2.3.1.28 2.3.1.28] </span></td></tr>

<tr id='resources'><td class="sblockLbl"><b>Resources:</b></td><td class="sblockDat"><span class='plainlinks'>[http://oca.weizmann.ac.il/oca-docs/fgij/fg.htm?mol=4cla FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=4cla OCA], [http://pdbe.org/4cla PDBe], [http://www.rcsb.org/pdb/explore.do?structureId=4cla RCSB], [http://www.ebi.ac.uk/pdbsum/4cla PDBsum], [http://prosat.h-its.org/prosat/prosatexe?pdbcode=4cla ProSAT]</span></td></tr>

[[http://www.uniprot.org/uniprot/CAT3_ECOLX CAT3_ECOLX]] This enzyme is an effector of chloramphenicol resistance in bacteria.

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== Publication Abstract from PubMed ==

Leucine-160 of chloramphenicol acetyltransferase (CAT) has been replaced by site-directed mutagenesis to investigate enzyme-ligand interactions at the 1-hydroxyl substituent of the substrate chloramphenicol. The consequences of the substitution of Leu-160 by glutamine and by phenylalanine were deduced from the steady-state kinetic parameters for acetyl transfer from acetyl-CoA to the 3-hydroxyl of chloramphenicol and its analogues 1-deoxychloramphenicol and 1-acetylchloramphenicol. The acetyl group of the latter, which is a substrate both in vivo and in vitro, could potentially bind in a similar position to the 1-hydroxyl of chloramphenicol, in close proximity to the side chain of Leu-160. In the case of Gln-160 CAT, large increases in Km for the three acetyl acceptors were accompanied by small decreases in kcat and in apparent affinity for acetyl-CoA. Such results are consistent with the introduction of the relatively hydrophilic amide in place of the delta-methyl groups of Leu-160. The kinetic properties of Phe-160 CAT were unexpected in that Km for each of the three acetyl acceptors was unchanged or reduced, compared to the equivalent parameters for the wild-type enzyme, whereas kcat fell significantly (44-83-fold) in each case. The ratios of specificity constants (kcat/Km) for the acetylation of chloramphenicol compared with the alternative acyl acceptors were similar for wild-type and mutant enzymes. As the residue substitutions for Leu-160 do not result in enhanced discrimination against the binding and acetylation of 1-acetylchloramphenicol, it appears unlikely that the 1-acetyl group binds to the CAT active site in the same position as that occupied by the 1-hydroxyl of chloramphenicol.(ABSTRACT TRUNCATED AT 250 WORDS)

Alternative binding modes for chloramphenicol and 1-substituted chloramphenicol analogues revealed by site-directed mutagenesis and X-ray crystallography of chloramphenicol acetyltransferase.,Murray IA, Lewendon A, Williams JA, Cullis PM, Shaw WV, Leslie AG Biochemistry. 1991 Apr 16;30(15):3763-70. PMID:2015231<ref>PMID:2015231</ref>

From MEDLINE&reg;/PubMed&reg;, a database of the U.S. National Library of Medicine.<br>

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<div class="pdbe-citations 4cla" style="background-color:#fffaf0;"></div>

*[[Chloramphenicol acetyltransferase|Chloramphenicol acetyltransferase]]

[[Category: Bacillus coli migula 1895]]

[[Category: Chloramphenicol O-acetyltransferase]]

[[Category: Leslie, A G.W]]