Publisher Summary Catalase exerts a dual function: (1) decomposition of H 2 O 2 to give H 2 O and O 2 (catalytic activity) and (2) oxidation of H donors, for example, methanol, ethanol, formic acid, phenols, with the consumption of 1 mol of peroxide (peroxide activity) The kinetics of catalase does not obey the normal pattern Measurements of enzyme activity at substrate saturation or determination of the K s is therefore impossible In contrast to reactions proceeding at substrate saturation, the enzymic decomposition of H 2 O 2 is a first-order reaction, the rate of which is always proportional to the peroxide concentration present Consequently, to avoid a rapid decrease in the initial rate of the reaction, the assay must be carried out with relatively low concentrations of H 2 O 2 (about 001 M) This chapter discusses the catalytic activity of catalase The method of choice for biological material, however, is ultraviolet (UV) spectrophotometry Titrimetric methods are suitable for comparative studies For large series of measurements, there are either simple screening tests, which give a quick indication of the approximative catalase activity, or automated methods

Catalase in vitro

Studies on the quantitative and qualitative characterization of erythrocyte glutathione peroxidase

The autoxidation of pyrogallol was investigated in the presence of EDTA in the pH range 7.9–10.6.

The rate of autoxidation increases with increasing pH. At pH 7.9 the reaction is inhibited to 99% by superoxide dismutase, indicating an almost total dependence on the participation of the superoxide anion radical, O2·−, in the reaction. Up to pH 9.1 the reaction is still inhibited to over 90% by superoxide dismutase, but at higher alkalinity, O2·− -independent mechanisms rapidly become dominant.

Catalase has no effect on the autoxidation but decreases the oxygen consumption by half, showing that H2O2 is the stable product of oxygen and that H2O2 is not involved in the autoxidation mechanism.

A simple and rapid method for the assay of superoxide dismutase is described, based on the ability of the enzyme to inhibit the autoxidation of pyrogallol.

A plausible explanation is given for the non-competitive part of the inhibition of catechol O-methyltransferase brought about by pyrogallol.

https://febs.onlinelibrary.wiley.com/doi/epdf/10.1111/j.1432-1033.1974.tb03714.x

Involvement of the Superoxide Anion Radical in the Autoxidation of Pyrogallol and a Convenient Assay for Superoxide Dismutase

There is an increasing amount of experimental evidence that oxidative stress is a causal, or at least an ancillary, factor in the neuropathology of several adult neurodegenerative disorders, as well as in stroke, trauma, and seizures. At the same time, excessive or persistent activation of glutamate-gated ion channels may cause neuronal degeneration in these same conditions. Glutamate and related acidic amino acids are thought to be the major excitatory neurotransmitters in brain and may be utilized by 40 percent of the synapses. Thus, two broad mechanisms--oxidative stress and excessive activation of glutamate receptors--are converging and represent sequential as well as interacting processes that provide a final common pathway for cell vulnerability in the brain. The broad distribution in brain of the processes regulating oxidative stress and mediating glutamatergic neurotransmission may explain the wide range of disorders in which both have been implicated. Yet differential expression of components of the processes in particular neuronal systems may account for selective neurodegeneration in certain disorders.

https://science.sciencemag.org/content/sci/262/5134/689.full.pdf

Oxidative stress, glutamate, and neurodegenerative disorders

O2- oxidizes the [4Fe-4S] clusters of dehydratases, such as aconitase, causing-inactivation and release of Fe(II), which may then reduce H2O2 to OH- +OH.. SODs inhibit such HO. production by scavengingO2-, but Cu, ZnSODs, by virtue of a nonspecific peroxidase activity, may peroxidize spin trapping agents and thus give the appearance of catalyzing OH. production from H2O2. There is a glycosylated, tetrameric Cu, ZnSOD in the extracellular space that binds to acidic glycosamino-glycans. It minimizes the reaction of O2- with NO. E. coli, and other gram negative microorganisms, contain a periplasmic Cu, ZnSOD that may serve to protect against extracellular O2-. Mn(III) complexes of multidentate macrocyclic nitrogenous ligands catalyze the dismutation of O2- and are being explored as potential pharmaceutical agents. SOD-null mutants have been prepared to reveal the biological effects of O2-. SodA, sodB E. coli exhibit dioxygen-dependent auxotrophies and enhanced mutagenesis, reflecting O2(-)-sensitive biosynthetic pathways and DNA damage. Yeast, lacking either Cu, ZnSOD or MnSOD, are oxygen intolerant, and the double mutant was hypermutable and defective in sporulation and exhibited requirements for methionine and lysine. A Cu, ZnSOD-null Drosophila exhibited a shortened lifespan.

Superoxide Radical and Superoxide Dismutases

Publisher Summary This chapter reviews the ultrastructural and florescence histochemical characteristics of the mature rabbit substantia nigra and neostriatum, as a frame of reference for the developmental study. Biochemical investigations have been reported on neostriatal dopamine concentrations and the relative uptake and accumulation of 3H-dopamine by this tissue from fetal to adult stages, to provide quantitative data for correlation with the florescence information. The development of the neurons of the substantia nigra and their axons, which project to the neostriatum, can be witnessed from their appearance at day 14 of gestation to their maturation in early postnatal life. The chapter also discusses that a distinct substantia nigra, pars compacta, and reticulata, can be recognized by florescence microscopy by day 20 of gestation. Electron microscopy reveals that the young neurons are multipolar with numerous developing dendrites, some of which exhibit early synaptic junctions. Moreover, in an attempt to identify the dopamine-containing axon, the ultrastructure of adult neostriatum incubated in 5-hydroxydopamine has been reported. The chapter also discusses the possible significance of these findings as related to dopamine secretion.

Dopamine-containing neurons of the substantia nigra and their terminals in the neostriatum.

Alcohol and catecholamine disposition:: A role for tetrahydroisoquinoline alkaloids

Alcohol and catecholamine disposition: a role for tetrahydroisoquinoline alkaloids

HEINZ bodies are refractile granules appearing within erythrocytes and stainable with certain dyes such as crystal violet1–3. In man, their appearance is often associated with anaemia due to drug administration (for example, phenylhydrazine, menadione) or contact with other agents (for example, aniline dyes), particularly in certain sensitive individuals. Although the granules can be readily prepared experimentally by treatment of animals or isolated erythrocytes with various drugs, their chemical composition is only partially resolved and their metabolic disposition is unknown.

Gerald Cohen

Papers

Dopamine-containing neurons of the substantia nigra and their terminals in the neostriatum.

Alcohol and catecholamine disposition:: A role for tetrahydroisoquinoline alkaloids

Alcohol and catecholamine disposition: a role for tetrahydroisoquinoline alkaloids

Radioactive (Chromium-51) Heinz Bodies

A possible role of strandin in the regulation of catecholamine transport across membranes