The Mechanism of the Periodate Oxidation of Aromatic Systems. III. A Kinetic Study of the Periodate Oxidation of Catechol

Weidman, Stuart W.; Kaiser, E. T.

doi:10.1021/ja00976a024

Cited by 84 publications

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“…Evidently, periodate must form a bidentate chelate with the catechol moiety of Dopa in order to oxidize it. 25 Such chelates appear to form with both bound and unbound Dopa, in contrast to pH-induced oxidations where bound Dopa is at least partially shielded from oxidation (Figure 3) 16 . Results from an experiment in which the symmetric configuration was exposed to periodate after contact suggest that Dopa binding to mica may not be stable to periodate (Figure S3).…”

Section: Results and Analysesmentioning

confidence: 99%

Hydrophobic Enhancement of Dopa-Mediated Adhesion in a Mussel Foot Protein

et al. 2012

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Dopa (3,4-dihydroxyphenylalanine) is recognized as a key chemical signature of mussel adhesion and has been adopted into diverse synthetic polymer systems. Dopa’s notorious susceptibility to oxidation, however, poses significant challenges to the practical translation of mussel adhesion. Using a Surface Forces Apparatus to investigate the adhesion of Mfp3 (mussel foot protein 3) slow, a hydrophobic protein variant of the Mfp3 family in the plaque, we have discovered a subtle molecular strategy correlated with hydrophobicity that appears to compensate for Dopa instability. At pH 3, where Dopa is stable, Mfp3 slow like Mfp3 fast adhesion to mica is directly proportional to the mol% of Dopa present in the protein. At pH 5.5 and 7.5, however, loss of adhesion in Mfp3 slow was less than half that occurring in Mfp3 fast, purportedly because Dopa in Mfp3 slow is less prone to oxidation. Indeed, cyclic voltammetry showed that the oxidation potential of Dopa in Mfp3 slow is significantly higher than in Mfp3 fast at pH 7.5. A much greater difference between the two variants was revealed in the interaction energy of two symmetric Mfp3 slow films (Ead = −3 mJ/m2). This energy corresponds to the energy of protein cohesion which is notable for its reversibility and pH-independence. Exploitation of aromatic hydrophobic sequences to protect Dopa against oxidation as well as to mediate hydrophobic and H-bonding interactions between proteins provides new insights for developing effective artificial underwater adhesives.

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Section: Results and Analysesmentioning

confidence: 99%

Hydrophobic Enhancement of Dopa-Mediated Adhesion in a Mussel Foot Protein

et al. 2012

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“…In addition, IO 4 − reacts with organic molecules by electron transfer without producing I-DBPs. 38 Therefore, IO 4 − formation is preferable from a toxicological point of view as compared to I-DBPs.…”

Section: ■ Materials and Methodsmentioning

confidence: 99%

Chlorination of Iodide-Containing Waters in the Presence of CuO: Formation of Periodate

Liu

Salhi

Croué

et al. 2014

Environ. Sci. Technol.

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It has been shown previously that the disproportionation of halogen-containing oxidants (e.g., HOCl, HOBr, and ClO2) is enhanced by a CuO-catalyzed process. In this study, the transformation of iodine during chlorination in the presence of CuO was investigated. There is no significant enhancement of the disproportionation of hypoiodous acid (HOI) in the presence of CuO. The formation rate of iodate (IO3(-)) in the CuO-HOCl-I(-) system significantly increased when compared to homogeneous solutions, which was ascribed to the activation of HOCl by CuO enhancing its reactivity toward HOI. In this reaction system, iodate formation rates increase with increasing CuO (0-0.5 g L(-1)) and bromide (0-2 μM) doses and with decreasing pH (9.6-6.6). Iodate does not adsorb to the CuO surfaces used in this study. Nevertheless, iodate concentrations decreased after a maximum was reached in the CuO-HOCl-I(-)(-Br(-)) systems. Similarly, the iodate concentrations decrease as a function of time in the CuO-HOCl-IO3(-) or CuO-HOBr-IO3(-) system, and the rates increase with decreasing pH (9.6-6.6) due to the enhanced reactivity of HOCl or HOBr in the presence of CuO. It could be demonstrated that iodate is oxidized to periodate by a CuO-activated hypohalous acid, which is adsorbed on the CuO surface. No periodate could be measured in filtered solutions because it was mainly adsorbed to CuO. The adsorbed periodate was identified by scanning electron microscopy plus energy dispersive spectroscopy and X-ray photoelectron spectroscopy.

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“…Kaiser and Weidman (1964) examined the oxidation of hydroquinone by an electron transfer process and found as product a monomeric compound, p-benzoquinone, with an intense absorption band at 2420 ,~. The periodate oxidation of pyrocatechol (Weidman and Kaiser, 1966) results in the formation of a dimeric compound which does not have a definitive absorption band. The oxidation of pyrogallol by electron transfer results in a 3600 3200 2800 2400 2, Wavelength, A aromatic amino acids 353 product like that formed by 02 oxidation.…”

Section: Discussionmentioning

confidence: 99%

The Alteration of Some Aromatic Amino Acids and Polyhydric Phenols by Clay Minerals

Thompson¹

1973

Clays and clay miner.

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Abstract-These studies concern the catalytic activity of clays on amino acids, particularly tyrosine. Polyhydric phenols were included to help understand the tyrosine reactions.Below pH 3, tyrosine is adsorbed on clay minerals by cation exchange. Above pH 3, oxidative degradation of tyrosine occurs, the L-isomer altering more rapidly. The rate of alteration depends upon the particular clay mineral, surface modifications such as polyphosphate treatment, heating, and the presence of copper, aluminium, and mercury. A free radical mechanism is proposed for the alteration.INTRODUCTION THE EFFECT of clay minerals on amino acids is of importance not only because these organic compounds are used to date sediments, but also because of the possible role of fine-grained silicates in the prebiotic synthesis of polypeptides. Both areas of study depend upon the catalytic activity of clay minerals. Age dating, as indicated by the loss of optical activity or racemization, (Bada et al., 1970;Kvenvolden and Peterson, 1970) is considered to be a first order reaction, but independent of any specific influence of the fine-grained sediments. The development of polypeptides from amino acids by 'template catalysis' on clay mineral surfaces has been studied by Degens, Mathejar andJackson (1970) andJackson (1971). Their findings were of exceptional interest; the L-isomer, which predominates in nature, showed an increased adsorption and polymerization rate over that of the Disomer.These investigations prompted the study of the catalytic activity of clays on some optically active amino acids and polyhydric phenols. The following compounds were selected: D-and L-tyrosine, Dand L-phenylalanine, pyrogallol, pyrocatechol, resorcinol and hydroquinone. These particular amino acids were chosen because they absorb light in the u.v. a property which makes possible the quantitative determination of concentration and structural changes.

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The Mechanism of the Periodate Oxidation of Aromatic Systems. III. A Kinetic Study of the Periodate Oxidation of Catechol

Cited by 84 publications

References 0 publications

Hydrophobic Enhancement of Dopa-Mediated Adhesion in a Mussel Foot Protein

Hydrophobic Enhancement of Dopa-Mediated Adhesion in a Mussel Foot Protein

Chlorination of Iodide-Containing Waters in the Presence of CuO: Formation of Periodate

The Alteration of Some Aromatic Amino Acids and Polyhydric Phenols by Clay Minerals

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