No abstract

No abstract

A procedure for modification of hemin chloride by FcCH 2 NH 2 (Fc ferrocenyl) in the presence of 1-(dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride and N-hydroxysuccinimide affords two main products 1 and 2 with mono-and bis-amidated propionic acid residues. Monoamidated conjugate 1 was loaded into the apoenzyme of horseradish peroxidase (HRP) to afford an electrochemically and catalytically active reconstituted enzyme Fc-HRP with remarkably altered substrate specificity. With ABTS as substrate, the reactivity of Fc-HRP drops threefold compared with native HRP as a result of a lowering of the maximal rate V m . Compared with HRP the reactivity of Fc-HRP towards water-soluble ferrocenes is even higher at low concentrations of the latter, the rate increase being accompanied by a change in rate law: in contrast to first-order kinetics in ferrocenes for native HRP, there is a Michaelis dependence for Fc-HRP. Molecular modeling suggests creation of an artificial hydrophobic binding site within a triangle confined by the ferrocenyl residue and the two phenyl rings of Phe 68 and 179. The site is believed to be responsible for the kinetically meaningful binding between ferrocene substrates and Fc-HRP which manifests in the saturation kinetics.

We report on a fluidic resonant waveguide grating (RWG) biosensor system that enables medium throughput measurements of cellular responses under microfluidics in a 32-well format. Dynamic mass redistribution assays under microfluidics differentiate the cross-desensitization process between the β2-adrenoceptor agonist epinephrine and the adenylate cyclase activator forskolin mediated signaling. This system opens new possibility to study cellular processes that are otherwise difficult to achieve using conventional RWG configurations.

/k(R)-1 are 1.7 and 1.6, respectively. Based on the known X-ray structural data for the active site of GO, it has been tentatively suggested that the enantioselectivity originates from the hydrophobic contact between the enzyme tyr-68 residue and the h 5 -C 5 H 5 ring of 1 , and a hydrogen bond network formed by his-516 and/or his-559 residues and the carboxylic group of the ferrocene derivative. The findings reported confirm the existence of enantioselective electron transfer between oxidoreductases and organometallic compounds with a planar chirality. The lack of kinetic enantioselectivity may be a result of i) the incorrect ratelimiting step, ii) unfavorable pH region, and iii) the deficit of charged groups attached to ferrocenes.