View source for 1ncw

[[Image:1ncw.gif|left|200px]]<br />
<applet load="1ncw" size="450" color="white" frame="true" align="right" spinBox="true" 
caption="1ncw, resolution 1.30&Aring;" />
'''CATIONIC CYCLIZATION ANTIBODY 4C6 IN COMPLEX WITH BENZOIC ACID'''<br />

==Overview==
Antibody 4C6 efficiently catalyzes a cationic cyclization reaction., Crystal structures of the antibody 4C6 Fab in complex with benzoic acid, and in complex with its eliciting hapten were determined to 1.30A and, 2.45A resolution, respectively. These crystal structures, together with, computational analysis, have elucidated a possible mechanism for the, monocyclization reaction. The hapten complex revealed a combining site, pocket with high shape complementarity to the hapten. This active site, cleft is dominated by aromatic residues that shield the highly reactive, carbocation intermediates from solvent and stabilize the carbocation, intermediates through cation-pi interactions. Modeling of an acyclic, olefinic sulfonate ester substrate and the transition state (TS), structures shows that the chair-like transition state is favored, and, trapping by water directly produces, trans-2-(dimethylphenylsilyl)-cyclohexanol, whereas the less favored, boat-like transition state leads to cyclohexene. The only significant, change observed upon hapten binding is a side-chain rotation of Trp(L89), which reorients to form the base of the combining site. Intriguingly, a, benzoic acid molecule was sequestered in the combining site of the, unliganded antibody. The 4C6 active site was compared to that observed in, a previously reported tandem cyclization antibody 19A4 hapten complex., These cationic cyclization antibodies exhibit convergent structural, features with terpenoid cyclases that appear to be important for, catalysis.

==About this Structure==
1NCW is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Mus_musculus Mus musculus] with BEZ and GOL as [http://en.wikipedia.org/wiki/ligands ligands]. Full crystallographic information is available from [http://ispc.weizmann.ac.il/oca-bin/ocashort?id=1NCW OCA]. 

==Reference==
Structural basis for antibody catalysis of a cationic cyclization reaction., Zhu X, Heine A, Monnat F, Houk KN, Janda KD, Wilson IA, J Mol Biol. 2003 May 23;329(1):69-83. PMID:[http://ispc.weizmann.ac.il//pmbin/getpm?pmid=12742019 12742019]
[[Category: Mus musculus]]
[[Category: Single protein]]
[[Category: Wilson, I.A.]]
[[Category: Zhu, X.]]
[[Category: BEZ]]
[[Category: GOL]]
[[Category: catalytic antibody]]
[[Category: cationic cyclization reaction]]
[[Category: immunoglobulin]]

''Page seeded by [http://ispc.weizmann.ac.il/oca OCA ] on Sun Nov 18 09:38:06 2007''