Chlorine Dioxide Oxidation of Guanosine 5‘-Monophosphate

Abstract

The reactions between aqueous ClO2 and guanosine 5'-monophosphate (5'-GMP) are investigated from pH 5.96 to 8.30. The decay of ClO2 follows mixed first-order and second-order kinetics. The addition of chlorite (0.01-0.05 M) to the reaction mixture suppresses the reaction rate and changes the observed decay of ClO2 to second-order. The reaction rates increase greatly with pH to give oxidized products. The second-order rate constant for the guanosine anion is 4.7 x 10(5 )M-1 s-1 and comprises a mixture of rate constants, k1k2/k-1. The ratio k1/k-1, with a calculated value of 2.4 x 10(-4), corresponds to the reversible reaction between ClO2 and the guanosine anion to generate ClO2- and the guanosyl radical. To determine k1/k-1 and k2, E values for guanosine and ClO2 are used as well as acid dissociation constants for guanosine and its radical. The value of k1 (1.1 x 10(5) M-1 s-1) represents the reaction between ClO2 and the guanosine anion as determined by initial rates. The second-order rate constant k2, with a value of 1.8 x 10(9 )M-1 s-1, represents the reaction between the guanosyl radical with a second molecule of ClO2 to generate a guanosyl-OClO adduct. The consumption of two mol of ClO2 per mol of 5'-GMP corresponds to a four-electron oxidation that gives ClO(2- )in the first step and HOCl in the second step. The 2',3',5'-tri-O-acetylated derivative of guanosine is used to more easily separate guanosine from its ClO2 oxidation products. Imidazolone and monochlorinated imidazolone are identified as products of the reaction between ClO2 and guanosine.

Virus Inactivation Mechanisms: Impact of Disinfectants on Virus Function and Structural Integrity

“…This is consistent with previous studies that demonstrated ClO 2 reacts more readily with amino acids than with nucleotides. 27,50,51 On the protein level, ClO 2 is a selective oxidant, which reacts mainly with Cys, Trp and Tyr. 27 Similar to 1 O 2 , CP degradation was specific and affected mainly peptide Ser84-Lys106 ( Figure 3, SI Table S5).…”

Subtle Differences in Virus Composition Affect Disinfection Kinetics and Mechanisms

“…The lack of genome damage is surprising given that the rather small size of the chlorine dioxide molecule should allow it to penetrate the virus capsid by way of the 1-to 2-nm pores in the capsid and to access the genome. The absence of genome damage may be explained by the fact that chlorine dioxide reacts more rapidly with some amino acids than with nucleotides (e.g., tryptophan reacts at least 75 times faster than the most susceptible nucleotide, G [11,41]) (see Table S7 in the supplemental material). Hence, by the time detectable genome damage has accumulated, the virus may have already been inactivated as a result of protein damage.…”

“…Contradictorily, Lim et al (2) report that genome damage is not sufficient to explain inactivation by chlorine dioxide. This is supported by the work of Napolitano et al, who suggested that inactivation should be due to protein damage, as ClO 2 reacts more readily with amino acids than with nucleotides (11). UV is often reported to cause fatal genome damage by forming pyrimidine dimers (4,12,13), and yet protein damage has also been reported (14,15).…”

Plasma membrane damage toCandida albicanscaused by chlorine dioxide (ClO2)

“…Recently, many studies have been conducted to investigate the mechanisms of reactions between ClO 2 and amino acid residues and enzymes in vitro (Noss et al 1985;Amor et al 2002;Napolitano et al 2005Napolitano et al , 2006Ison et al 2006;Ogata 2007). However, the physiological alter-ation of cell membranes, especially in vivo, has not been reported.…”