Electrocatalysis in proteins, nucleic acids and carbohydrates

Published: CHEMICAL RECORD 12, 27-45 Authors: Palecek, E., Bartosik, M., Ostatna, V., Trefulka, M. Year: 2012

Abstract

The ability of proteins to catalyze hydrogen evolution has been known for more than 80 years, but the poorly developed d.c. polarographic pre-sodium wave was of little analytical use. Recently, we have shown that by using constant current chronopotentiometric stripping analysis, proteins produce a well-developed peak H at hanging mercury drop and solid amalgam electrodes. Peak H sensitively reflects changes in protein structures due to protein denaturation, single amino acid exchange, etc. at the picomole level. Unmodified DNA and RNA do not yield such a peak, but they produce electrocatalytic voltammetric signals after modification with osmium tetroxide complexes with nitrogen ligands [Os(VIII)L], binding covalently to pyrimidine bases in nucleic acids. Recently, it has been shown that six-valent [Os(VI)L] complexes bind to 1,2-diols in polysaccharides and oligosaccharides, producing voltammetric responses similar to those of DNA-Os(VIII)L adducts. Electrocatalytic peaks produced by Os-modified nucleic acids, proteins (reaction with tryptophan residues) and carbohydrates are due to the catalytic hydrogen evolution, allowing determination of oligomers at the picomolar level. DOI 10.1002/tcr.201100029