Superoxide dismutase: Improved assays and an assay applicable to acrylamide gels☆

The Role of Superoxide Anion in the Autoxidation of Epinephrine and a Simple Assay for Superoxide Dismutase

more acidic solutions, with pH < 7 0, a few seconds elapsed before equilibrium was attained. Taking into account the ionization of the haem-linked group on MetMb and the higher oxidation state, the variation of Kb,. with pH is shown to confirm the conclusion that 2 moles ofH+ are liberated/mole of acidic MetMb. Using 6-1 for the pK of the group in MetMb as established in other studies, the results give apK of75 for the group in the higher oxidation state at 200 and I= 0 04. 3. The variation of KRb, with temperature gives AHO = 10-0 ± 2*0 kcal./g.mol.: if the ionization of the haem-linked group is allowed for, the value 9*0 ± 1.0 kcal./g.mol. is obtained. 4. The dependence of Kob. on ionic strength is in accord with a change in charge from + 1 on MetMb to zero on the higher oxidation state. 5. The results are shown to favour the ferryl ion structure, or an isomer of this structure, for the higher oxidation state. The isomeric structures would, in general, require the presence of another ionizing group in myoglobin, but no evidence for such an ionization could be found. With other direct evidence favouring the ferryl ion structure this is to be preferred, and the higher oxidation state may provisionally be named ferrylmyoglobin.

Tissue fractionation studies. 6. Intracellular distribution patterns of enzymes in rat-liver tissue

The respiratory chain and oxidative phosphorylation are of utter importance for a cell’s metabolism. Here, the energy won from ingested food is being converted into our body’s energy unit (adenosine triphosphate). As the name respiratory chain suggests, oxygen also plays an important role. The following article will explain how exactly this complex mechanism works and which substances may disable it.

The respiratory chain and oxidative phosphorylation.

Biochemical Adaptations in Muscle EFFECTS OF EXERCISE ON MITOCHONDRIAL OXYGEN UPTAKE AND RESPIRATORY ENZYME ACTIVITY IN SKELETAL MUSCLE

A microspectrophotometric method for the determination of cytochrome oxidase.

A microspectrophotometric method for the determination of succinic dehydrogenase.

In 1900, Michaelis used Janus green B as a supravital stain (20). He observed that filamentous structures within the cytoplasm of the cell stained with this dye and he recognized that these structures were similar to the elementary filaments described by Altmann in 1890 (1). Michaeis had specified that the diethyl derivative of Janus green was necessary for supravital staining. However, a number of subsequent investigators were unsuccessful in using this dye as a supravital stain, presumably because they did not use the diethyl derivative (10). Bensley reintroduced the use of Janus green B as a supravital stain (4). He was careful to use the diethyl derivative and he showed that the structures which stained with Janus green B were identical with the structures which Benda called mitochondria (3). The Janus green B staining reaction is oxygen dependent (5, 6), for although selective staining of mitochondria appears under partial anaerobic conditions, these structures become decolorized when all of the oxygen is removed. The Janus green B staining reaction is reversibly inhibited by cyanide (18, 19); when cyanide is added to supravitally stained mitochondria they become colorless whereas when the cyanide is subsequently removed by washing, the mitochondna regain their blue color. In vitro studies with Janus green B have indicated that this dye is reduced by the lactic dehydrogenase enzyme system (2). All of these observations suggest that Janus green B staining is dependent upon the enzyme activities of the cell. In order to clarify the enzymatic mechanism involved in the Janus green B staining reaction, we have undertaken a systematic study of the enzyme systems which are capable of reacting with Janus green B and its reduction products. Several preliminary notes have been published (7, 14, 15) and three completed papers are in press (16, 8, 9). Further studies on the reduction of Janus green B by the isolated cell components and on the binding of Janus green B to proteins and to isolated cell components are in progress and will be published soon (17).

Studies on the enzymatic basis for the janus green b staining reaction

The effect of alloxan on the permeability of toadfish islet slices was studied in vitro at 0 C, pH 7.0. When islet slices were incubated in d-mannitol-1-C14, a compound which does not enter cells, ...

Effect of alloxan on permeability of pancreatic islet tissue in vitro.

https://science.sciencemag.org/content/sci/120/3121/674.full.pdf

S. J. Cooperstein

Papers

A microspectrophotometric method for the determination of cytochrome oxidase.

A microspectrophotometric method for the determination of succinic dehydrogenase.

Studies on the enzymatic basis for the janus green b staining reaction

Effect of alloxan on permeability of pancreatic islet tissue in vitro.

Versatile anaerobic spectrophotometer cell.