Pyridoxal dehydrogenase is specific for DPNf and does not oxidize benzaldehyde, acetaldehyde, salicylaldehyde, or Sdeoxypyridoxal. In the presence of the latter compound, oxidation of pyridoxal is stimulated, apparently because of the occurrence of the dismutation reaction (ii). Z-Demethyl-Z-ethylpyridoxal is dehydrogenated at the same rate as pyridoxal. At high substrate concentrations the pH

Voltage-dependent potassium channels (Kv) are involved in various cellular signalling processes by governing the membrane potential of excitable cells. The cytosolic face of these α subunit-containing channels is associated with β subunits that can modulate channel responses. Surprisingly, the β subunit of the mammalian Kv1 channels, Kvβ2, has a high level of sequence homology with the aldo-ket...

Dismutation of superoxide has been shown previously to be catalyzed by stable nitroxide compounds. In the present study, the mechanism of superoxide (.O2-) dismutation by various five-membered ring and six-membered ring nitroxides was studied by electron paramagnetic resonance spectrometry, UV-visible spectrophotometry, cyclic voltammetry, and bulk electrolysis. Electron paramagnetic resonance ...

2 Introduction 3 Phylogenetic distribution and subcellular localization 3 Kinetics and mechanism 3 Molecular and chemical structure 5 Biological significance 8 Summary 9 References 10 Abstract Manganese superoxide dismutase (MnSOD) is the primary antioxidant enzyme that protects cells from oxidative stress by catalyzing dismutation of superoxide (O2 ) to hydrogen peroxide and oxygen in the mito...

Voltage-dependent potassium channels (Kv) are involved in various cellular signalling processes by governing the membrane potential of excitable cells. The cytosolic face of these α subunit-containing channels is associated with β subunits that can modulate channel responses. Surprisingly, the β subunit of the mammalian Kv1 channels, Kvβ2, has a high level of sequence homology with the aldo-ket...

Cinnamyl alcohol dehydrogenases (CAD; 1.1.1.195) catalyse the reversible conversion of p-hydroxycinnamaldehydes to their corresponding alcohols, leading to the biosynthesis of lignin in plants. Outside of plants their role is less defined. The gene for cinnamyl alcohol dehydrogenase from Helicobacter pylori (HpCAD) was cloned in Escherichia coli and the recombinant enzyme characterized for subs...

complex reacted rapidly with 02-. in a catalytic manner. The rate constant for O,-* dismutation was determined by competition of the iron porphyrin with Nitro Blue Tetrazolium in a xanthine/xanthine oxidase system at pH 10.1 ; a value of 3 x ~O'M-' .s-' at 20°C was obtained. The iron porphyrin had no effect on xanthine oxidase activity. Under our reaction conditions, at least 14 molecules of Oz...

The rational protein design algorithm DEZYMER was used to introduce the active site of nonheme iron superoxide dismutase (SOD) into the hydrophobic interior of the host protein, Escherichia coli thioredoxin (Trx), a protein that does not naturally contain a transition metal-binding site. Reconstitution of the designed protein, Trx-SOD, showed the incorporation of one high-affinity metal-binding...

The influence of the concentration of sodium, lithium, caesium, and potassium ions as well as of the ionic strength of the solutions used on the dismutation rate of ascorbyl radicals has been investigated. While the dismutation rate was not influenced by Li+, it decreased, however, with increasing concentrations of the other ions investigated. The largest effect was obtained with Na+. This chan...

This enzyme is provisionally referred to as “malic” enzyme. The present paper deals with further observations on the kinetics and other properties of the purified enzyme.’ The enzyme is totally inactive in the absence of Mn++. Mg++ can replace Mn++ but is less effective. Further evidence has been obtained indicating that free oxalacetate is not an intermediate in Reaction 1 and that both Reacti...