On phagocytosing a microorganism, the neutrophil (polymorphonuclear leukocyte, PMN) consumes oxygen at a sharply elevated rate1. The oxygen is used to kill the microorganism, presumably being used to produce a potent oxidizing agent or agents. Candidates for these bactericidal agents are singlet oxygen, hydroxyl radical and chlorinating agents (that is, species containing 'active' Cl in a formal +1 oxidation state: HOCl, Cl2, N-chloroamides, and so on)1-5. We now report a semiquantitative assay for PMN-generated active chlorine based on its trapping with 1,3,5-trimethoxybenzene (TMB). Using this assay, we have found that at least 28% of the oxygen consumed by stimulated normal human PMNs is converted to active chlorinating agents.

The self-complementing dodecamer 5'-CGCGAATTCGCG-3' and its complexes with the antibiotic netropsin and the restriction endonuclease EcoRI provide substrates of known three-dimensional structure to study the stereochemistry and mechanism of the artificial nuclease of 1,10-phenanthroline-copper ion [(OP)2Cu+]. Analysis of the reaction products with the 5'-32P dodecamer on 20% sequencing gels has demonstrated the presence of 3'-phosphoglycolate ends in addition to 3'-phosphomonoester ends expected from previous studies. A reaction intermediate, which is a precursor to 3'-phosphomonoester termini, has been trapped; in contrast, no comparable species for the 5'-phosphomonoester termini can be detected when 3'-labeled DNAs are utilized as substrates. The reactive oxidative species formed by the coreactants (OP)2Cu+ and hydrogen peroxide is distinguishable in its chemistry from the hydroxyl radicals produced by cobalt-60 gamma-irradiation. The freely diffusible hydroxyl radicals generated by cobalt-60 irradiation produce equivalent amounts of 3'-phosphomonoester and 3'-phosphoglycolate termini whereas the 3'-phosphomonoesters are the preferred product of (OP)2Cu+ and H2O2. On the basis of the structures of the products obtained, the principal site of attack of the coordination complex is on the C-1 of the deoxyribose within the minor groove. This conclusion is supported by the footprinting of netropsin binding to the dodecamer. Crystallographic results have demonstrated that netropsin binds to the minor groove at the central AATT residue. A clear protection of attack by the coordination complex at the deoxyriboses associated with A-5, T-6, T-7, and C-9 is fully consistent with attack from the minor groove without intercalation during the course of the cleavage reaction.(ABSTRACT TRUNCATED AT 250 WORDS)

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Environmental pollution is both a worldwide and a local issue, and microplastic pollution in particular is receiving increased attention due to its prevalence and bioaccumulation potential affecting the food chain. This laboratory experiment uses current, research-based methods such that the students can determine the extent of microplastic pollution in local soil samples. This laboratory experiment can be used as either a 2 or 3 week mini-research-project for first-year undergraduate students in either an introductory chemistry course for nonmajors or a general chemistry course for majors. The laboratory experiment gives students exposure to sieving, density gradients, and exposure to the Fenton reagent to isolate microplastics from soil samples, which are then analyzed and quantified under stereomicroscope magnification. Several general chemistry topics common to most first-year chemistry courses (density and solution concentration calculations, etc.) are emphasized during the laboratory experiment. From postexperiment assessments, students showed a marked improvement in select skill sets and knowledge of the microplastic pollution problem, and some students recognized their misconceptions concerning research following the completion of this laboratory experiment.