Peroxidases catalyze the dehydrogenation by hydrogen peroxide (H2O2) of various phenolic and endiolic substrates in a peroxidatic reaction cycle. In addition, these enzymes exhibit an oxidase activity mediating the reduction of O2 to superoxide (O2.-) and H2O2 by substrates such as NADH or dihydroxyfumarate. Here we show that horseradish peroxidase can also catalyze a third type of reaction tha...

Unlike lactoperoxidase and horseradish peroxidase, thyroid peroxidase catalyzed the oxidation of hydroquinone mostly by way of 2-electron transfer. This conclusion could be derived from three independent experiments: ESR measurements of p-benzosemiquinone, trapping the unpaired electron by cytochrome c, and spectrophotometric analysis of catalytic intermediates of the enzymes. The 1-electron fl...

Oxidation of isonicotinic acid hydrazide (isoniazid) by horseradish peroxidase at the expense of H2O2 yielded reactive species which were able to reduce nitroblue tetrazolium and bleach p-nitrosodimethylaniline. Nicotinic acid hydrazide oxidation did not cause these effects. At slightly alkaline pH, oxidation of isonicotinic acid hydrazide by horseradish peroxidase proceeded at the expense of m...

Lignin peroxidase shares several structural features with the well-studied horseradish peroxidase and cytochrome c peroxidase but carries a higher redox potential. Here the heme domain of lignin peroxidase and the lignin peroxidase cyanide adduct was examined by 1HNMR spectroscopy, including nuclear Overhauser effect and two-dimensional measurements, and the findings were compared with those fo...

The absorption of macromolecules from the small intestine of rats was studied in terms of the amount of peroxidase activity that appeared in thoracic duct lymph after a 10 mg dose of horseradish peroxidase had been injected directly into the lumen of the duodenum. When the horseradish peroxidase was injected as a solution in saline no peroxidase activity was detected in the lymph. When ethyl al...

Cell lineages during development of leeches can be ascertained by injection of horseradish peroxidase as a tracer into identified cells at early stages of embryogenesis. The injected embryos continue their normal development, in the course of which horseradish peroxidase is passed on in catalytically active form to the descendants of the injected cell. The distribution of the tracer enzyme and ...

A label-free biological sensor, which is based on the resonant transmission phenomenon of a thin metallic mesh, is proposed in the terahertz wave region. By using this sensor, we demonstrate the highly sensitive detection of small amounts of protein horseradish peroxidase. For quantitative investigation of the sensitivity of our sensor, horseradish peroxidase was printed on the metallic mesh su...