The chloroplast, as the seat of chlorophyll pigments in plants, occupies a unique position in the economy of the green cell. In recent years there has been a renewed interest in the reactions and properties of chloroplasts as a result of the work of Hill (11, 12) and Hill and Scarisbrick (13, 14) who demonstrated that the reaction characteristic of photosynthesis in green plants, the evolution of oxygen, occurs in appreciable quantities in isolated chloroplasts under the influence of light and in the presence of suitable oxidants (2, 7, 8, 26). In the course of an investigation of oxygen evolution by isolated chloroplasts it was deemed important to explore their enzymatic composition. Of special interest were considered enzymes capable of participating in oxidation-reduction reactions, and more particularly, those localized principally, if not entirely, in the chloroplasts. This paper presents evidence that a copper enzyme, polyphenoloxidase (otherwise known as tyrosinase or catecholase), is localized in the chloroplasts of spinach beet (chard), Beta vu?garis.

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Copper enzymes in isolated chloroplasts. polyphenoloxidase in beta vulgaris

Publisher Summary This chapter discusses the assay of catalases and peroxidases are: (1) catalase assay by disappearance of peroxide; (2) method for crude cell extracts; (3) direct spectrophotometric assay of catalase and peroxidase in cells and tissues; and (4) peroxidase assay by spectrophotometric measurements of the disappearance of hydrogen donor or the appearance of their colored oxidation products. Two methods are described for the catalase assay by disappearance of peroxide are: ultraviolet spectrophotometry and permanganate titration. Ultraviolet spectrophotometryis a method devised, on the basis of the absorption curves for peroxide solutions, for determining the activity of catalase by direct measurements of the decrease of light absorption in the region 230 to 250 mμ caused by the decomposition of hydrogen peroxide by catalase. In the case of method for crude cell extracts, oxygen evolution caused by the decomposition of hydrogen peroxide is measured with the conventional manometric technique. Peroxidase assay by spectrophotometric measurements of the disappearance of hydrogen donor or the appearance of their colored oxidation products includes the guaiacol test and the pyrogallol test.

The assay of catalases and peroxidases.

Hundreds of thousands of copies of DNA sequences have been incorporated into the genomes of higher organisms.

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Repeated Sequences in DNA

Physiological actions of taurine

Zinc ions are key structural components of a large number of proteins. The binding of zinc stabilizes the folded conformations of domains so that they may facilitate interactions between the proteins and other macromolecules such as DNA. The modular nature of some of these zinc-containing proteins has allowed the rational design of site-specific DNA binding proteins. The ability of zinc to be bound specifically within a range of tetrahedral sites appears to be responsible for the evolution of the side range of zinc-stabilized structural domains now known to exist. The lack of redox activity for the zinc ion and its binding and exchange kinetics also may be important in the use of zinc for specific functional roles.

https://science.sciencemag.org/content/sci/271/5252/1081.full.pdf

The Galvanization of Biology: A Growing Appreciation for the Roles of Zinc

MAGNUSSEN, G. (1947), "Akute og knoneke Forifninger mad Carbromal, et hyppigt anvendt 8avordsmiddel, som ik7ce bor kunne kebes i Haandkeb", Ugeskr. Laeg., 109: 359. MINAKI, L., and GILLEN, J. B. (1937), "Blood Bromide Investigations In Psychotic Epileptics", Brit. med. J., 2: 850. MIZUHAaA, S., and OOMORI, S. (1961), "A New Sulphur-Containing Amino Acid", Arch. Biochem. Biophys., 92: 53. NATELSON, S., and CLARK, M. K. (1955), "Estimation of Bromide on Fingertip Blood In Bromide Intoxication", Proc. 80c. expo Bioi. (N.Y.), 90: 723. NATELSON, S., SHEID, B., and LEUIGHTON, D. R. (1962), "Bromide Normally Present In Human Serum", Clin. Chem., 8: 630. PIHKANEN, T., and HARENKO, A. (1962), "Bromoisovalum Intoxication: Its Differential Diagnosis from Neurological Disorders", Acta Neurol. scand., 38: 209. REYE, G. H., and JOFFE, J. R. (1959), "A New Screening Test for Bromide Intoxication", Amer. J. Psychiat., 116: 166. RONALD, J. (1959), "Carbromal Intoxication", Lancet, 1: 888. SCHMIDT, G. (1956), "Occurrence of a-ethyl-a-hydroxybutyrlc Acid Excretion after Carbromal Intake", Naunyn8chmiederberg's Arch. expo Path. Pharmak., 229: 67. SHAW, F. H., and SHAW, E. (1959), "A New Outlook on Carbromal", Aust. J. Pharm., 40: 214. SOREMARK, R. (1960), "Excretion of Bromide by Human Urine", Acta physiol. scand., 50: 306. STEEL, M., and JOHNSTONE, J. M. (1959), "Addiction to Carbromal", Brit. med, J., 2: 118. TAKEDA, S. (1911), "Bromural, Its Distribution and Decomposition In the Animal Organism", Arch. into Pharmacodyn., 21: 203. TAMMINEN, V., and ALHA, A. R. (1959), "2-ethylbutyrylurea, a Metabolite of 2-bromo-2-ethyl-butyrylurea (Carbromal) ", Acta chem. [enn., 32s: 119. TILLIM, S. J. (1957), "Bromide Intoxication and Quantitative Determination In Serum", Amer. J. Psychiat., 114: 232. TRETHOWAN, W. H., and PAWLOFF, T. (1962), "A Clinical and Experimental Study of Bromide Intoxication with Special Reference to Bromureldes", MED. J. AUST., 1: 229. TURNER, L. K. (1959), "Poisoning by Carbromal and Bromvaletone", MED. J. AUST., 1: 729. WIKOFF, H., BRUNNER, R. A., and ALLISON, H. W. (1940), "The Normal Bromide Content of the Blood of Healthy Individuals", Amer. J. clin. Path., 10: 234. WOLLHEIM, F. (1958), "On the Elimination of BromlneContaining Hypnotics", Acta pharm. toe. (Kbh.), 15: 1.

The biochemistry of semen and of the male reproductive tract.

Male reproductive function and semen.

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Carbonic anhydrase. Purification and nature of the enzyme.

CARBONIC anhydrase which catalyses the reversible reaction H2CO3 ⇄ CO2 + H2O is present in large concentrations in the red blood corpuscles and some cells of gastric mucosa of mammals. This enzyme plays an important part in accelerating the carbon dioxide output in the lungs; it appears also to promote the formation of hydrochloric acid by the parietal cells of gastric mucosa1.

Thaddeus Mann

Papers

The biochemistry of semen and of the male reproductive tract.

Male reproductive function and semen.

Carbonic anhydrase. Purification and nature of the enzyme.

Sulphanilamide as a Specific Inhibitor of Carbonic Anhydrase

Studies on the metabolism of semen: 3. Fructose as a normal constituent of seminal plasma. Site of formation and function of fructose in semen.