Superoxide dismutases (SODs) are ubiquitous enzymes with metal cofactors (Wolfe-Simon et al. 2005; Miller 2012). They are extremely efficient enzymes, the conversion of superoxide to diacid and H2O2 (Eq. 1) with a first-order rate constant approach leads to a diffusion-limited rate:
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(1)
In addition to being kinetically fast, they are also widespread across soil organisms and evolved billions of years ago (the 2017 case). There are three SOD families with different metal cofactors: nickel SOD (NiSOD); copper / zinc SOD (CuZnSOD); and manganese / iron SOD (MnFeSOD) (Miller 2012).
SOD protects against the harmful effects of superoxide – but what are the effects of superoxide? Interestingly, superoxide reacts with most biomolecules at slow rates (Winterbourn and Metodiewa 1999; Halliwell and Gutteridge 2007). The main targets of superoxide are Fe-S clusters and Fe mononuclear enzymes (Imlay 2013). Gu and Imlay (2013) have elegantly shown that Fe superoxide can abstract from Fe-containing mononuclear enzymes in vitro (reversible), which is replaced by Zn, resulting in a non-functional protein. Requires re-metallization mononuclear Fe enzymes. SODs are therefore essential for reducing superoxide-induced mismetation. We confirmed that SODs play an important role in phytoplankton, especially in the Southern Ocean, where dissolved Zn levels are high (Vance et al. 2017) and Fe and Mn concentrations can also be very low (Afternoon et al., 2011). . Thus, Gmail Numeric Code 6922 issue metalation can strongly affect the vitality of the organism, especially with regard to the low Mn content (Imlay 2014). SOD expression can also lead to increased urn levels: x-wiley: 23782242: media: lol210233: lol210233-math-0002 (Eq. 1; Mittler et al. 2011), which may have several adverse effects (discussed below). Superoxide can also react directly with urn: x-wiley: 23782242: medium: lol210233: lol210233-math-0003, to produce a hydroxyl radical, but superoxide reacts with urn: x-wiley: 23782242: unlike lo231031-physiological conditions (Haber and Weiss 1932; Wardman and Candeias 1996; Imlay 2003).
SODs also have an atypical temperature relationship with a higher rate of superoxide dismutation at lower temperatures (Perelman et al. 2006), which increases the requirements for rapid metal tracking. warming of the polar regions. Different regulation of SOD under different conditions suggests that superoxide is itself a signaling molecule (Case 2017). The regulation of SOD can therefore be attributed not only to the suppression of superoxide levels itself, but also to the modulation of superoxide consumption and H2O2 production. Various viruses even encode SOD (e.g., Cao et al. 2002), which can alter the regulatory program of hosts by interfering with redox signaling. An empirical list of drivers in the SOD fitness scene can be useful. In other words, is superoxide a normally toxic product of metabolism, or is it used for self-signaling? If phytoplankton SODs are commonly used to prevent superoxide poisoning, there may be increased metal cofactor requirements in the warming ocean.
Catalases and catalase peroxidases
Catalysts (CAT) for old urn: x-wiley: 23782242: medium: lol210233: lol210233-math-0005 metabolizing enzymes that dismute two molecules in the urn: x-wiley: 23782242: media: lol2623meters generally generated photos Zamocky3 et al. 2008; Vlasits et al. 2010; Zámocký et al. 2012; Tehrani and Moosavi-Movahedi 2018):
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(2)
Monofunctional CATs use heme to catalyze the surface reaction. Peroxidase CATs and Mn-CATs have similar catalytic mechanisms, except that peroxidase CATs can use an external reducing agent to reduce the active site (Vlasits et al. 2010; Tehrani and Moosavi-Movahedi 2018). For peroxidases, the general stoichiometry is as follows (where R is a reducing agent):
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