Respiratory enzymes

The extension of the useful storage life of plant and animal products beyond a few days at room temperature presents a series of complex biochemical, physical, microbial, and economic challenges. Respiratory enzyme systems and other enzymes ia these foods continue to function. Their reaction products can cause off-davors, darkening, and softening. Microbes contaminating the surface of plants or animals can grow ia cell exudates produced by bmises, peeling, or size reduction. Fresh plant and animal tissue can be contaminated by odors, dust, iasects, rodents, and microbes. 

Mode of Action. The fundamental biochemical lesion produced by arsenicals is the result of reaction between As " and the sulfhydryl groups of key respiratory enzymes such as pymvate and a-ketoglutarate dehydrogenases. 

This is the reverse Pasteur or Crabtree effect and is also known as glucose inhibition or cataboHte repression. In the presence of higher sugar concentrations, synthesis of respiratory enzymes such as cytochromes is inhibited. 

Tyler DD, Sutton CM Respiratory enzyme systems in mitochondrial membranes. In Membrane Structure and Function, vol 5. Bittar EE (editor). Wiley, 1984. 

Figure 17-1. Summary of glycolysis. 0, blocked by anaerobic conditions or by absence of mitochondria containing key respiratory enzymes, eg, as in erythrocytes.

Chance, B. and Williams, G.R. (1955). Respiratory enzymes and oxidative phosphorylation. I. Kinetics of oxygen utilisation. J. Biol. Chem. 217, 383-393. 

Schults BE, Chan SI. 2001. Structures and proton-pumping strategies of mitochondrial respiratory enzymes. Annu Rev Biophys Biomol Struct 30 23. 

Roth SH, Skrajny B, Bennington R, et al. 1997. Neurotoxicity of hydrogen sulfide may result from inhibition of respiratory enzymes. Proc West Pharmacol Soc 40 41-43. 

Hydrogen cyanide is toxic because the cyanide ion has high affinity for metal ions and so binds to the metal-containing cellular respiratory enzymes. Heme proteins such as cytochrome oxidase are complexed, resulting in asphyxiation at the cell level. 

A principle in metabolic regulation that allows one to identify the inhibited step within a metabolic pathway as that reaction for which the concentrations of reactants and products rise and fall, respectively, from their steady-state values when an inhibitor is introduced. In the context of the electron transfer chain, the crossover-point refers to that reaction step demarking the transition from more reduced to more oxidized respiratory enzymes. 

F. lipmann, Symposium on Respiratory Enzymes, Univ. Wisconsin Press, Madison, p. 48 (1942). 

Kooy and Royall (1994) have shown that cultured endothelial cells produce peroxynitrite when stimulated by bradykinen. They used an ultrasensitive chemiluminescent assay based on luminol developed by Radi et al. (1993). Peroxynitrite is a potent toxin to trypanosomes, attacking both sulfhydryl dependent enzymes and respiratory enzymes (Rubbo et al., 1994). Radi et al. (1994) have also shown that it is far more damaging to mitochondria than nitric oxide. 

Otto H. Warburg Physiology/Medicine Respiratory enzymes... 

Chance, B., and G. R. Williams, Respiratory enzymes in oxi-dativt- phosphorylation II. Difference spectra.. /. Biol. 

Warburg postulated a respiratory enzyme for the activation of oxygen. 

Warburg deduced the iron-prophyrin presence in the respiratory enzyme. 

Subcellular Organelles. Toxic metals may disrupt the structure and function of a number of organelles. For example, enzymes associated with the endoplasmic reticulum may be inhibited, metals may be accumulated in the lysosomes, respiratory enzymes in the mitochondria may be inhibited, and metal inclusion bodies may be formed in the nucleus. 

Caldwell, R. (1969). Thermal compensation of respiratory enzymes in tissue of the goldfish. Comparative Biochemistry and Physiology 31,79-93. 

Berberine inhibits oxidative decarboxylation of yeast pyruvic acid (310) the same dose has, however, no effect upon aerobic glycolysis, Warburg s respiratory enzymes, indophenol oxidase, etc. Berberine and tetrahydroberberine have an inhibitory effect on oxidation of (+ )-alanine in rat kidney homogenates (498). Berberine and palmatine show a specific inhibitory effect upon cholinesterase in rabbit spleen and on pseudocholinesterase in horse serum (499). Berberine inhibits cellular respiration in ascitic tumors and even in tissue cultures (500-502). The specific toxic effect of berberine on the respiration of cells of ascitic tumors in mice was described (310). The glycolysis was not found to be affected, but the uptake of oxygen was smaller. Fluorescence was used in order to demonstrate berberine in cellular granules. Hirsch (503) assumed that respiration is inhibited by the effect of berberine on the yellow respiratory enzymes. Since the tumorous tissue contains a smaller number of yellow respiratory enzymes than normal tissue it is more readily affected by berberine. Subcutaneous injections of berberine, palmatine, or tetrahydropalmatine significantly reduce the content of ascorbic acid in the suprarenals, which is not affected by hypophysectomy (504). 

Muscolo, A., Panuccio, M.R., Sidari, M. The effect of phenols on respiratory enzymes in seed germination -Respiratory enzyme activities during germination of Pinus laricio seeds treated with phenols extracted from different forest soils. Plant Growth Regul. 2001 35 31-35. 

Mutations in Nuclear Genes That Affect Mitochondrial Respiratory Enzymes. 104... 

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