The occurrence of protein tyrosine nitration under disease conditions is now firmly established and represents a shift from the signal transducing physiological actions of (.)NO to oxidative and potentially pathogenic pathways. Tyrosine nitration is mediated by reactive nitrogen species such as peroxynitrite anion (ONOO(-)) and nitrogen dioxide ((.)NO2), formed as secondary products of (.)NO metabolism in the presence of oxidants including superoxide radicals (O2(.-)), hydrogen peroxide (H2O2), and transition metal centers. The precise interplay between (.)NO and oxidants and the identification of the proximal intermediate(s) responsible for nitration in vivo have been under controversy. Despite the capacity of peroxynitrite to mediate tyrosine nitration in vitro, its role on nitration in vivo has been questioned, and alternative pathways, including the nitrite/H2O2/hemeperoxidase and transition metal-dependent mechanisms, have been proposed. A balanced analysis of existing evidence indicates that (i) different nitration pathways can contribute to tyrosine nitration in vivo, and (ii) most, if not all, nitration pathways involve free radical biochemistry with carbonate radicals (CO3(.-)) and/or oxo-metal complexes oxidizing tyrosine to tyrosyl radical followed by the diffusion-controlled reaction with (.)NO2 to yield 3-nitrotyrosine. Although protein tyrosine nitration is a low-yield process in vivo, 3-nitrotyrosine has been revealed as a relevant biomarker of (.)NO-dependent oxidative stress; additionally, site-specific nitration focused on particular protein tyrosines may result in modification of function and promote a biological effect. Tissue distribution and quantitation of protein 3-nitrotyrosine, recognition of the predominant nitration pathways and individual identification of nitrated proteins in disease states open new avenues for the understanding and treatment of human pathologies.

https://www.pnas.org/content/pnas/101/12/4003.full.pdf

Nitric oxide, oxidants, and protein tyrosine nitration

The Golden Age of Transfer Hydrogenation

Background— Meat consumption is inconsistently associated with development of coronary heart disease (CHD), stroke, and diabetes mellitus, limiting quantitative recommendations for consumption leve...

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Red and Processed Meat Consumption and Risk of Incident Coronary Heart Disease, Stroke, and Diabetes Mellitus A Systematic Review and Meta-Analysis

s of Papers, 221st ACS National Meeting, San Diego, CA, April 1-5, 2001; American Chemical Society:Washington, DC, 2001; INOR287. (b) Dijkstra, H. P.; Slagt, M. Q.; McDonald, A.; Kruithof, C. A.; Kreiter, R.; Mills, A. M.; Lutz, M.; Spek, A. L.; Klopper, W.; van Klink, G. P. M.; van Koten, G. Eur. J. Inorg. Chem. 2003, 830. (c) Mehendale, N. C.; Bezemer, C.; van Walree, C. A.; Klein Gebbink, R. J. M.; van Koten, G. J. Mol. Catal. A 2006, 257, 167. (d)Mehendale, N. C.; Sietsma, J. R. A.; de Jong, K. P.; vanWalree, C. A.; Gebbink, R. J. M. K.; van Koten, G. Adv. Synth. Catal. 2007, 349, 2619. (e) Mehendale, N. C.; Lutz, M.; Spek, A. L.; Klein Gebbink, R. J. M.; van Koten, G. J. Organomet. Chem. 2008, 693, 2971. (f)McDonald, A. R.; Dijkstra, H. P.; Suijkerbuijk, B.M. J. M.; van Klink, G. P. M.; van Koten, G.Organometallics 2009, 28, 4689. (g) McDonald, A. R.; Franssen, N.; van Klink, G. P. M.; van Koten, G. J. Organomet. Chem. 2009, 694, 2153. (h) O’Leary, P.; vanWalree, C. A.; Mehendale, N. C.; Sumerel, J.; Morse, D. E.; Kaska, W. C.; van Koten, G.; Klein Gebbink, R. J. M. Dalton Trans. 2009, 4289. (164) Gimenez, R.; Swager, T. M. J. Mol. Catal. A 2001, 166, 265. (165) Poyatos, M.; Marquez, F.; Peris, E.; Claver, C.; Fernandez, E. New J. Chem. 2003, 27, 425. (166) Yu, K.; Sommer, W.; Weck, M.; Jones, C. W. J. Catal. 2004, 226, 101. (167) Sommer,W. J.; Yu, K.; Sears, J. S.; Ji, Y.; Zheng, X.; Davis, R. J.; Sherrill, C. D.; Jones, C. W.; Weck, M. Organometallics 2005, 24, 4351. (168) Brookhart, M.; Huang, Z.; MacArthur, A. H.; Carson, E. C.; Goldman, A.; Scott, S. L.; Vicente, B. C. Abstracts of Papers, 239th ACS National Meeting, San Francisco, CA, March 21-25, 2010; American Chemical Society: Washington, DC, 2010; CATL-79. (169) del Pozo, C.; Corma, A.; Iglesias, M.; Sanchez, F. Organometallics 2010, 29, 4491.

Dehydrogenation and related reactions catalyzed by iridium pincer complexes

Metal-ligand cooperation (MLC) has become an important concept in catalysis by transition metal complexes both in synthetic and biological systems. MLC implies that both the metal and the ligand are directly involved in bond activation processes, by contrast to "classical" transition metal catalysis where the ligand (e.g. phosphine) acts as a spectator, while all key transformations occur at the metal center. In this Review, we will discuss examples of MLC in which 1) both the metal and the ligand are chemically modified during bond activation and 2) bond activation results in immediate changes in the 1st coordination sphere involving the cooperating ligand, even if the reactive center at the ligand is not directly bound to the metal (e.g. via tautomerization). The role of MLC in enabling effective catalysis as well as in catalyst deactivation reactions will be discussed.

Metal–Ligand Cooperation

A Family of Active Iridium Catalysts for Transfer Hydrogenation of Ketones

Kinetics and mechanism of the decomposition of S-nitrosoglutathione by l-ascorbic acid and copper ions in aqueous solution to produce nitric oxide.

Kinetic studies on the degradation of three commonly used pesticides in Jamaica, dieldrin [(1R,4S,5S,8R)-1,2,3,4,10,10-hexachloro-6,7-epoxy-1,4,4a,5,6,7,8,8a-octahydro-endo,exo-1,4:5,8-dimethanonaphthalene] and α- and β-endosulfan 6,7,8,9,10,10-hexachloro--1,5,5a,6,9,9a-hexahydro-6,9-methano-2,4,3-benzodioxathiepin 3-oxide), were carried out under laboratory conditions that simulated those of tropical agroecosystems. Studies included measurements of rates of volatilization, hydrolysis, and photolysis. Volatility from EC formulations on glass surfaces at 30 °C was in in the order α-endosulfan>dieldrin>β-endosulfan (...)

Dynamics of pesticides in tropical conditions. 1. Kinetic studies of volatilization, hydrolysis, and photolysis of dieldrin and alpha- and beta-endosulfan

Tara P. Dasgupta

Papers

A Family of Active Iridium Catalysts for Transfer Hydrogenation of Ketones

Kinetics and mechanism of the decomposition of S-nitrosoglutathione by l-ascorbic acid and copper ions in aqueous solution to produce nitric oxide.

Dynamics of pesticides in tropical conditions. 1. Kinetic studies of volatilization, hydrolysis, and photolysis of dieldrin and alpha- and beta-endosulfan

Acrylamide in Caribbean foods - residual levels and their relation to reducing sugar and asparagine content.

A correlation between infrared stretching mode absorptions and structural angular distortions for the carbonato ligand in a wide variety of complexes