Purification of NADH: Hypothiocyanite oxidoreductase inStreptococcus sanguis

Courtois, Philippe; Pourtois, Michel

doi:10.1006/bmme.1996.0019

Cited by 16 publications

(13 citation statements)

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“…The identity of the bacterial HOSCN reductase(s) is not clear at the time of this writing, although the homology of GR (which is much better conserved between mammals and bacteria than thioredoxin reductase (21)) with H-TrxR, and our discovery that it can also turn over HOSCN, albeit less effectively than H-TrxR (Table 1), suggests it is a potential candidate for this role. P. H. Courtois and M. Pourtois (42) reported an NAD(P)H-dependent HOSCN oxidoreductase in Streptococcus sanguinis that has not been further characterized to our knowledge.…”

Section: The Conserved Active Sequence Of H-trxr and Gr (Cvn-vgc) Locmentioning

confidence: 93%

Selective Metabolism of Hypothiocyanous Acid by Mammalian Thioredoxin Reductase Promotes Lung Innate Immunity and Antioxidant Defense

Chandler

Nichols²,

Nick³

et al. 2013

Journal of Biological Chemistry

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Section: The Conserved Active Sequence Of H-trxr and Gr (Cvn-vgc) Locmentioning

confidence: 93%

Selective Metabolism of Hypothiocyanous Acid by Mammalian Thioredoxin Reductase Promotes Lung Innate Immunity and Antioxidant Defense

Chandler

Nichols²,

Nick³

et al. 2013

Journal of Biological Chemistry

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“…The commensal bacteria Streptococcus sanguinis , which is a normal component of the healthy human oral cavity flora, is among the strains of Streptococcus that have developed high expression of NADH-hypothiocyanite oxidoreductase that reduces OSCN − back to SCN. This adaptation allows the resident bacterium to resist oxidative stress by HOSCN, which benefits the host by preventing vacancy in the oral environment that could be taken advantage of by transient microbes [43]. It is tempting to speculate whether secretory epithelium have similar protective defenses against HOSCN.…”

Section: Biology Of Thiocyanatementioning

confidence: 99%

THIOCYANATE: A potentially useful therapeutic agent with host defense and antioxidant properties

Chandler

Day

2012

Biochemical Pharmacology

143

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Thiocyanate (SCN) functions in host defense as part of the secreted lactoperoxidase (LPO) microbicidal pathway. SCN is the preferred substrate for LPO-driven catalytic reduction of hydrogen peroxide (H2O2) forming hypothiocyanous acid (HOSCN). HOSCN is selectively generated by many peroxidase enzymes that can utilize SCN including: eosinophil peroxidase (EPO), gastric peroxidase (GPO), myeloperoxidase (MPO), salivary peroxidase (SPO), and thyroid peroxidase (TPO). These enzymes generate HOSCN through a two-electron halogenation reaction. HOSCN is a potent microbicidal agent that kills or nullifies invading pathogens but is better tolerated by host tissue. Some controversy exists as to whether physiologic levels of HOSCN are non-toxic to host tissue, but the disagreement appears to be based on results of enzymatic generation (yielding moderate steady-state exposure) versus direct high level acute exposure in mammalian cell lines. This apparent duality is also true of other endogenous oxidants such as hydrogen peroxide and relates to the difference between physiologically relevant oxidant production versus supra-physiologic bolus dosing approaches. SCN has antioxidant properties that include the ability to protect cells against oxidizing agents such as hypochlorous acid (HOCl) and repair protein chloramines. SCN is an important endogenous molecule that has the potential to interact in complex and elegant ways with its host environment and foreign organisms. SCN’s diverse properties as both host defense and antioxidant agent make it a potentially useful therapeutic.

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“…Multiple reports exist of NAD(P)H-dependent HOSCN resistance in oral and lactic streptococci associated with a purifiable inhibition “reversal factor” [2,121]. Similar HOSCN reductase activity was reported in a subset of antibiotic-resistant late isolate clinical strains of P. aeruginosa [75].…”

Section: Antimicrobial Properties Of Hoscnmentioning

confidence: 61%

Biochemical mechanisms and therapeutic potential of pseudohalide thiocyanate in human health

Chandler

Day

2015

Free Radical Research

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Thiocyanate (SCN−) is an ubiquitous molecule in mammalian biology, reaching up to mM concentrations in extracellular fluids. Two-electron oxidation of SCN− by H2O2 produces hypothiocyanous acid (HOSCN), a potent antimicrobial species. This reaction is catalyzed by chordate peroxidases (e.g., myeloperoxidase and lactoperoxidase), occurring in human secretory mucosa, including the oral cavity, airway and alimentary tract, and regulates resident and transient flora as part of innate immunity. Increasing SCN− levels limits the concentrations of a family of 2-electron oxidants (H2O2, hypohalous acids and haloamines) in favor of HOSCN formation, altering the oxidative impact on host tissue by substitution of repairable thiol and selenol oxidations instead of biomolecule degradation. This fine-tuning of inflammatory oxidation paradoxically associates with maintained host defense and decreased host injury during infections, due in part to phylogenetic differences in the thioredoxin reductase system between mammals and their pathogens. These differences could be exploited by pharmacologic use of SCN−. Recent preclinical studies have identified antimicrobial and anti-inflammatory effects of SCN− in pulmonary and cardiovascular animal models, with implications for treatment of infectious lung disease and atherogenesis. Further research is merited to expand on these findings and identify other diseases where SCN− may be of use. High oral bioavailability and an increased knowledge of the biochemical effects of SCN− on a subset of pro-inflammatory reactions suggest clinical utility.

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Purification of NADH: Hypothiocyanite oxidoreductase inStreptococcus sanguis

Cited by 16 publications

References 0 publications

Selective Metabolism of Hypothiocyanous Acid by Mammalian Thioredoxin Reductase Promotes Lung Innate Immunity and Antioxidant Defense

Selective Metabolism of Hypothiocyanous Acid by Mammalian Thioredoxin Reductase Promotes Lung Innate Immunity and Antioxidant Defense

THIOCYANATE: A potentially useful therapeutic agent with host defense and antioxidant properties

Biochemical mechanisms and therapeutic potential of pseudohalide thiocyanate in human health

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