High-resolution crystal structures of a "half sandwich"-type Ru(II) coordination compound bound to hen egg-white lysozyme and proteinase K.

The high-resolution X-ray crystal structures of the adducts formed between the "half sandwich"-type Ru(II) coordination compound [Ru(1,4,7-trithiacyclononane)(ethane-1,2-diamine)Cl] and two proteins, namely hen egg-white lysozyme and proteinase K, are presented. The structures unveil that upon reaction with both enzymes the Ru(II) compound is coordinated by solvent-exposed aspartate residues after releasing the chloride ligand (Asp101 in lysozyme, Asp200 and Asp260 in proteinase K), while retaining the two chelating ligands. The adduct with Asp101 residue at the catalytic cleft of lysozyme is accompanied by residue-specific conformational changes to accommodate the Ru(II) fragment, whereas the complexes bound at the two calcium-binding sites of proteinase K revealed minimal structural perturbation of the enzyme.

Structure-Function Analysis of the Periplasmic Escherichia coli Cyclophilin PpiA in Relation to Biofilm Formation.

The presence of peptidyl-prolyl cis/trans isomerases (PPIases, EC: 5.2.1.

Structural and functional analysis of cyclophilin PpiB mutants supports an in vivo function not limited to prolyl isomerization activity.

Escherichia coli cyclophilin PpiB is a peptidyl-prolyl cis/trans isomerase (PPIase, EC: 5.2.1.

Microbial host selection and periplasmic folding in Escherichia coli affect the biochemical characteristics of a cutinase from Fusarium oxysporum.

A cutinase from the mesophilic fungus Fusarium oxysporum (FoCut5a) was functionally expressed in different hosts and their recombinant products were characterized regarding their activity, thermostability and tolerance in organic solvents. The cutinase gene cut5a was expressed in the BL21 and Origami 2 Escherichia coli strains and the resulting protein was folded either in the cytoplasm or in the periplasmic space, with the aim of correct formation of disulfide bonds. Increase of thermostability occurred when the enzyme was expressed in the oxidative cytoplasm of Origami 2.

Enzymatic synthesis of model substrates recognized by glucuronoyl esterases from Podospora anserina and Myceliophthora thermophila.

Glucuronoyl esterases (GEs) are recently discovered enzymes that are suggested to cleave the ester bond between lignin alcohols and xylan-bound 4-O-methyl-D-glucuronic acid. Although their potential use for enhanced enzymatic biomass degradation and synthesis of valuable chemicals renders them attractive research targets for biotechnological applications, the difficulty to purify natural fractions of lignin-carbohydrate complexes hampers the characterization of fungal GEs. In this work, we report the synthesis of three aryl alkyl or alkenyl D-glucuronate esters using lipase B from Candida antarctica (CALB) and their use to determine the kinetic parameters of two GEs, StGE2 from the thermophilic fungus Myceliophthora thermophila (syn.