Molecular interaction of inorganic mercury(<scp>ii</scp>) with catalase: a spectroscopic study in combination with molecular docking

Chen, Linfeng; Zhang, Jing; Zhu, Yaxian; Zhang, Yong

doi:10.1039/c5ra15301h

Cited by 27 publications

(7 citation statements)

References 49 publications

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“…Because the RC has a relatively large surface, a large number of deep voids and variable electrostatic surface profile, plenty of places for the Hg 2+ ions to bind are assured. This is shown in the 3D movie attached to the electronic version of the MS. For comparison with other proteins, even the weak binding constants of mercury(II) to bacterial RC are much larger than those to other proteins such as catalase (Chen et al 2015) or bovine serum albumin (Chunmei et al 2014). From the large number of binding sites and relatively high binding affinities, one can conclude that the RC serves as sponge for mercury(II) ions.…”

Section: Discussionmentioning

confidence: 98%

Characterization of mercury(II)-induced inhibition of photochemistry in the reaction center of photosynthetic bacteria

2017

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Mercuric contamination of aqueous cultures results in impairment of viability of photosynthetic bacteria primarily by inhibition of the photochemistry of the reaction center (RC) protein. Isolated reaction centers (RCs) from Rhodobacter sphaeroides were exposed to Hg ions up to saturation concentration (~ 10 [Hg]/[RC]) and the gradual time- and concentration-dependent loss of the photochemical activity was monitored. The vast majority of Hg ions (about 500 [Hg]/[RC]) had low affinity for the RC [binding constant K ~ 5 mM] and only a few (~ 1 [Hg]/[RC]) exhibited strong binding (K ~ 50 μM). Neither type of binding site had specific and harmful effects on the photochemistry of the RC. The primary charge separation was preserved even at saturation mercury(II) concentration, but essential further steps of stabilization and utilization were blocked already in the 5 < [Hg]/[RC] < 50 range whose locations were revealed. (1) The proton gate at the cytoplasmic site had the highest affinity for Hg binding (K ~ 0.2 μM) and blocked the proton uptake. (2) Reduced affinity (K ~ 0.05 μM) was measured for the mercury(II)-binding site close to the secondary quinone that resulted in inhibition of the interquinone electron transfer. (3) A similar affinity was observed close to the bacteriochlorophyll dimer causing slight energetic changes as evidenced by a ~ 30 nm blue shift of the red absorption band, a 47 meV increase in the redox midpoint potential, and a ~ 20 meV drop in free energy gap of the primary charge pair. The primary quinone was not perturbed upon mercury(II) treatment. Although the Hg ions attack the RC in large number, the exertion of the harmful effect on photochemistry is not through mass action but rather a couple of well-defined targets. Bound to these sites, the Hg ions can destroy H-bond structures, inhibit protein dynamics, block conformational gating mechanisms, and modify electrostatic profiles essential for electron and proton transfer.

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Section: Discussionmentioning

confidence: 98%

Characterization of mercury(II)-induced inhibition of photochemistry in the reaction center of photosynthetic bacteria

2017

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“…The modified double-logarithm form of the Stern-Volmer equation helps in determining the binding parameters for a quencher-fluorophore interaction [25]. The modified equation is written as 1.…”

Section: Spectral Analysis Of L-cys-capped Gqdsmentioning

confidence: 99%

L-cysteine functionalized graphene quantum dots for sub-ppb detection of As (III)

Naseh¹,

Singh²,

Ansari³

et al. 2021

Nanotechnology

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Here, we report functionalized graphene quantum dots (GQDs) for the optical detection of arsenic at room temperature. GQDs with the fluorescence of three fundamental colors (red, green, and blue) were synthesized and functionally capped with L-cysteine (L-cys) to impart selectively towards As (III) by exploiting the affinity of L-cys towards arsenite. The optical characterization of GQDs was carried out using UV–vis absorption spectroscopy, Fourier transform infrared spectroscopy, and fluorescence spectrometry, and the structural characterizations were performed using transmission electron microscopy. The fluorescence results showed instantaneous quenching in intensity when the GQDs came in contact with As (III) for all test concentrations over a range from 0.025 to 25 ppb, which covers the permissible limit of arsenic in drinking water. The experimental results suggested excellent sensitivity and selectivity towards As (III).

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“…Long-term exposure of Cr 6+ increases the substrate levels (superoxide radicals) of SOD, whereas SOD activity decreased with the increase in its substrate levels in this study, indicating that antioxidant defense probably has been impaired in sea cucumbers. In terms of CAT, as an important enzymatic scavenger (Chen et al, 2015), removing the H 2 O 2 by catalyzing its decomposition. The present study found that significantly lower CAT activities were found in groups 100 and 200 mg/kg than those in control group.…”

Section: Immunity Responsesmentioning

confidence: 99%

Effects of chronic dietary hexavalent chromium on bioaccumulation and immune responses in the sea cucumber Apostichopus japonicus

Chan

Wang

Shi

et al. 2021

Preprint

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Sea cucumbers Apostichopus japonicus were exposed to five concentrations of dietary hexavalent chromium [0 (control), 100, 200, 400, and 800 mg Cr6+/kg dry weight] amended with K2Cr2O7 for 30 days. The bioaccumulation and immune responses [antioxidant enzymes: superoxide dismutase (SOD) and catalase (CAT); hydrolytic enzymes: acid phosphatase (ACP) and alkaline phosphatase (AKP)] of sea cucumbers were subsequently evaluated. This study found that the order of Cr accumulation in the experimental tissues was respiratory tree > intestine > body wall. Significantly lower SOD activities occurred in the 400 mg/kg group compared to that in the control group. Higher dietary Cr6+ exposure (400 and 800 mg Cr6+ /kg dry weight) did not negatively alter the CAT activities, but significantly inhibited CAT activities in 100 mg/kg group, compared to control group. ACP activities in groups 200, 400 and 800 mg/kg were significantly lower than those in control group, while no significant differences occurred in AKP activities among groups. The present study provides important information into the bioaccumulation and immune responses of the sea cucumber A. japonicus in response to chronic dietary Cr6+ exposure.

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Molecular interaction of inorganic mercury(ii) with catalase: a spectroscopic study in combination with molecular docking

Abstract: Interaction of inorganic mercury(ii) with catalase was investigated using spectroscopic methods. Moreover, molecular docking was used to distinguish the interactions between different species of inorganic mercury(ii) and catalase.

Cited by 27 publications

References 49 publications

Characterization of mercury(II)-induced inhibition of photochemistry in the reaction center of photosynthetic bacteria

Characterization of mercury(II)-induced inhibition of photochemistry in the reaction center of photosynthetic bacteria

L-cysteine functionalized graphene quantum dots for sub-ppb detection of As (III)

Effects of chronic dietary hexavalent chromium on bioaccumulation and immune responses in the sea cucumber Apostichopus japonicus

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