Mamothibe A. Thamae, Tebello Nyokong
文献索引：10.1002/jpp.551
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The interaction of histidine, cysteine, NO and nitrite with cobalt(II) N,N′,N″,N″′-tetramethyltetra-3,4-tetrapyridinoporphyrazine ([CoIItmtppa]4+) is reported. Metal-based autoreduction of [CoIItmtppa]4+ occurs with the formation of the [CoItmtppa(−2)]3+ species in the presence of histidine and cysteine. Kinetic data for the auto reduction of [CoIItmtppa]4+ in the presence of these amino acids gave the rate constants kf = 2.1 × 101 and 2.8 dm3 mol−1 s−1, for cysteine and histidine, respectively. One molecule of NO or nitrite was found to coordinate to the [CoIItmtppa]4+ species. The equilibrium and rate constants for the coordination of the nitric oxide were K = 2.3 × 104 dm3 mol−1 and kf = 7.5 dm3 mol−1 s−1, respectively. The coordination of nitrite to [CoIItmtppa]4+ occurred with an equilibrium constant of K = 2.0 × 102 dm3 mol−1 and a rate constant of kf = 4.0 × 10−3 dm3 mol−1 s−1. There was no evidence for the coordination of two molecules of nitrite to the [CoIItmtppa]4+ species. Copyright © 2001 John Wiley & Sons, Ltd.