Structural analysis of coniferyl alcohol 9-O-methyltransferase from Linum nodiflorum reveals a novel active-site environment.

Coniferyl alcohol 9-O-methyltransferase from Linum nodiflorum (Linaceae) catalyzes the unusual methylation of the side-chain hydroxyl group of coniferyl alcohol. The protein was heterologously expressed in Escherichia coli as a hexahistidine derivative and purified for crystallization. Diffracting crystals were obtained of the pure protein and of its selenomethionine derivative, as well as of complexes with coniferyl alcohol and with S-adenosyl-L-homocysteine together with coniferyl alcohol 9-O-methyl ether (PDB entries 4ems, 4e70 and 4evi, respectively).

Stereo- and regioselective azide/alkyne cycloadditions in carbonic anhydrase II via tethering, monitored by crystallography and mass spectrometry.

The carbonic anhydrase II mutant His64Cys was prepared and applied to tethered alkyne/azide cycloaddition reactions. The azide component could be tethered to the enzyme surface through a disulfide bridge, while the alkyne component was reversibly coordinated through a sulfonamide anchor to the zinc ion in the original catalytic center of the enzyme. The incipient orientation of the reactants in the binding site and of the formed triazole product were characterized by crystallography.

Bidentate Zinc chelators for alpha-carbonic anhydrases that produce a trigonal bipyramidal coordination geometry.

A series of new zinc binding groups (ZBGs) has been evaluated kinetically on 13 carbonic anhydrase (CA) isoforms. The fragments show affinity for all isoforms with IC(50) values in the range of 2-11 microM. The crystal structure of hCA II in complex with one such fragment reveals a bidentate binding mode with a trigonal-bipyramidal coordination geometry at the Zn(2+) center.