Verdoheme formation in Proteus mirabilis catalase

Mechanisms of oxidant generation by catalase

“…3). However, emerging studies suggesting interaction of ferrocyanide with enzyme‐bound NADPH and resultant disruption of NADPH‐heme electronic linkage offer an alternative explanation for this effect 36 . In our studies, both sodium azide and 3‐AT, which disrupt peroxide access, enhanced UVB light‐mediated ROS production 5 .…”

“…This site restricts both peroxide and water access to the heme iron and functions to optimally position peroxide molecules for cleavage by catalase 33–35 . The enzyme inhibitor 3‐amino‐1,2,4‐triazole (3‐AT) has been reported to inactivate catalase by disrupting this binding site 33,36 . It is important to note that analysis of the 2‐Å‐resolution structure of inhibitor‐bound enzyme indicates the potential presence of water molecules within the substrate channel.…”

“…In the presence of higher concentrations of cyanide, interaction of the anion with catalase heme is likely to block substrate access to heme iron as well as limiting the activity of the charge relay network, rendering both structures unable to participate in the UVB‐induced production of ROS. The increased generation of ROS that is observed in the presence of 3‐AT and sodium azide suggests that the presence of reactants at the peroxide binding site, and the activity of the charge relay network implicated in peroxide degradation, 35–38 are both important in UVB light‐mediated oxidant production. This is not in agreement with the contention that ROS generation results from light‐induced heme degradation 39,40 .…”

The Chlorite Dismutase (HemQ) from Staphylococcus aureus Has a Redox-sensitive Heme and Is Associated with the Small Colony Variant Phenotype

“…Following reaction with even very low eq of H 2 O 2 (Ͻ5) the Soret band shifts from 403 to 407 nm prior to bleaching. Production of verdoheme, a product of H 2 O 2 -mediated heme lysis in catalases, peroxidases, and heme oxygenase (52,55,56) is not clearly observed.…”

Homology modeling and phylogenetic relationships of catalases of an opportunistic pathogen Rhizopus oryzae

“…Compared to the catalase from B. taurus (PDB code 3RGP) CAT1 has identical amino acids, in CAT2 and CAT4 there is only a Met-Leu mutation while CAT3 lacks two amino acids besides the Met-Asp mutation. NADPH is known to have a protective effect preventing the oxidative degradation of catalases and besides the essential His, a Met near the active center also plays an important role in maintaining the catalase functionality (Andreoletti et al, 2009). According to our results none of the four R. oryzae catalases is supposed to bind the NADPH including CAT1, although it is a small-subunit catalase.…”