scholarly journals Characterization of Electron Mediator Preference of Aerococcus viridans-Derived Lactate Oxidase for Use in Disposable Enzyme Sensor Strips

2017 ◽  
pp. 1703
Keyword(s):  
Lactate Oxidase ◽  
Electron Mediator ◽  
Enzyme Sensor ◽  
Aerococcus Viridans

scholarly journals Employment of 1-Methoxy-5-Ethyl Phenazinium Ethyl Sulfate as a Stable Electron Mediator in Flavin Oxidoreductases-Based Sensors

Sensors ◽  
2020 ◽  
Vol 20 (10) ◽  
pp. 2825
Author(s):  
Maya Fitriana ◽  
Noya Loew ◽  
Arief Budi Witarto ◽  
Kazunori Ikebukuro ◽  
Koji Sode ◽  
...  
Keyword(s):  
Glucose Dehydrogenase ◽  
High Sensitivity ◽  
Lactate Oxidase ◽  
Electron Mediator ◽  
Effective Electron ◽  
Ethyl Sulfate ◽  
Enzyme Sensor ◽  
Aerococcus Viridans ◽  
Enzyme Sensors ◽  
Lactate Sensor

In this paper, a novel electron mediator, 1-methoxy-5-ethyl phenazinium ethyl sulfate (mPES), was introduced as a versatile mediator for disposable enzyme sensor strips, employing representative flavin oxidoreductases, lactate oxidase (LOx), glucose dehydrogenase (GDH), and fructosyl peptide oxidase (FPOx). A disposable lactate enzyme sensor with oxygen insensitive Aerococcus viridans-derived engineered LOx (AvLOx), with A96L mutant as the enzyme, was constructed. The constructed lactate sensor exhibited a high sensitivity (0.73 ± 0.12 μA/mM) and wide linear range (0–50 mM lactate), showings that mPES functions as an effective mediator for AvLOx. Employing mPES as mediator allowed this amperometric lactate sensor to be operated at a relatively low potential of +0.2 V to 0 V vs. Ag/AgCl, thus avoiding interference from uric acid and acetaminophen. The lactate sensors were adequately stable for at least 48 days of storage at 25 °C. These results indicated that mPES can be replaced with 1-methoxy-5-methyl phenazinium methyl sulfate (mPMS), which we previously reported as the best mediator for AvLOx-based lactate sensors. Furthermore, this study revealed that mPES can be used as an effective electron mediator for the enzyme sensors employing representative flavin oxidoreductases, GDH-based glucose sensors, and FPOx-based hemoglobin A1c (HbA1c) sensors.

scholarly journals FMN-dependent oligomerization of putative lactate oxidase from Pediococcus acidilactici

2019 ◽  
Author(s):  
Yashwanth Ashok ◽  
Mirko M. Maksimainen ◽  
Tuija Kallio ◽  
Pekka Kilpeläinen ◽  
Lari Lehtiö
Keyword(s):  
Hydrogen Peroxide ◽  
Active Site ◽  
Pediococcus Acidilactici ◽  
Active Site Residues ◽  
Lactate Oxidase ◽  
Monooxygenase Activity ◽  
Aerococcus Viridans ◽  
Lactate Levels

AbstractLactate oxidases belong to a group of FMN-dependent enzymes and they catalyze a conversion of lactate to pyruvate with a release of hydrogen peroxide. Hydrogen peroxide is also utilized as a read out in biosensors to quantitate lactate levels in biological samples. Aerococcus viridans lactate oxidase is the best characterized lactate oxidase and our knowledge of lactate oxidases relies largely to studies conducted with that particular enzyme. Pediococcus acidilactici lactate oxidase is also commercially available for e.g. lactate measurements, but this enzyme has not been characterized before in detail. Here we report structural characterization of the recombinant enzyme and its co-factor dependent oligomerization. The crystal structures revealed two distinct conformations in the loop closing the active site, consistent with previous biochemical studies implicating the role of loop in catalysis. Despite the structural conservation of active site residues when compared to Aerococcus viridans lactate oxidase we were not able to detect either oxidase or monooxygenase activity when L-lactate or other potential alpha hydroxyl acids were used as a substrate. Pediococcus acidilactici lactate oxidase is therefore an example of a misannotation of an FMN-dependent enzyme, which catalyzes likely a so far unknown oxidation reaction.

Molecular and antibiotic susceptibility characterization of Aerococcus viridans isolated from porcine urinary infection

2016 ◽  
Vol 184 ◽  
pp. 7-10 ◽  
Author(s):  
Luisa Z. Moreno ◽  
Carlos E.C. Matajira ◽  
Vasco T.M. Gomes ◽  
Ana Paula S. Silva ◽  
Renan E. Mesquita ◽  
...  
Keyword(s):  
Antibiotic Susceptibility ◽  
Urinary Infection ◽  
Aerococcus Viridans

X-ray Structures of Aerococcus viridans Lactate Oxidase and Its Complex with d-Lactate at pH 4.5 Show an α-Hydroxyacid Oxidation Mechanism

2008 ◽  
Vol 378 (2) ◽  
pp. 436-446 ◽  
Author(s):  
Makio Furuichi ◽  
Nobuhiro Suzuki ◽  
Balasundaresan Dhakshnamoorhty ◽  
Hirotaka Minagawa ◽  
Ryosuke Yamagishi ◽  
...  
Keyword(s):  
Oxidation Mechanism ◽  
Lactate Oxidase ◽  
X Ray ◽  
Aerococcus Viridans

scholarly journals Europium-Doped Ceria Nanocrystals as Nanozyme Fluorescent Probes for Biosensing

2021 ◽  
Vol 5 (1) ◽  
pp. 53
Author(s):  
Ali Othman ◽  
Akhtar Hayat ◽  
Silvana Andreescu
Keyword(s):  
Fluorescent Dyes ◽  
Aqueous Media ◽  
Doped Ceria ◽  
New Wave ◽  
Lactate Oxidase ◽  
Fluorescence Sensing ◽  
Combined Use ◽  
Direct Fluorescence ◽  
Average Size

Molecular nanoprobes with intrinsic enzyme-like activity represent a new wave of technology for rapid and sensitive detection of molecular targets. This work reports synthesis and characterization of novel and well-dispersed europium-doped ceria nanocrystals (EuCe NCs) with self-integrated catalytic and fluorescence sensing functions. The NCs have an average size of ∼5 nm and exhibit bright and stable fluorescence for more than 6 months in aqueous media. Their dual cooperative function as both a catalyst and fluorescent probe was explored to develop a universally applicable fluorescence-based biosensing method to monitor enzyme reactions and quantitatively measure clinically relevant molecules. Sensing capabilities are demonstrated for detection of H2O2, glucose/glucose oxidase, lactate/lactate oxidase, phosphatase activity, and the catecholamine neurotransmitter, dopamine. Results indicate that EuCe NCs not only provide high enzyme-mimetic activity, but also impart direct fluorescence sensing ability enabling all-in-one recognition, catalytic amplification, and the detection of biomolecular targets. The EuCe nanozyme offers a stable alternative to the more complex systems based on the combined use of natural enzymes and fluorescent dyes. The high stability and fluorescence detection capabilities demonstrate that EuCe NCs have the potential to be used as a generic platform in chemical and biological sensing and bioimaging applications.

A Wearable Biosensor Based on Bienzyme Gel-Membrane for Sweat Lactate Monitoring by Mounting on Eyeglasses

2020 ◽  
Vol 20 (3) ◽  
pp. 1495-1503 ◽  
Author(s):  
Lili Zhang ◽  
Jian Liu ◽  
Zhenling Fu ◽  
Liguo Qi
Keyword(s):  
Physical Exercise ◽  
Low Noise ◽  
Lactate Oxidase ◽  
Electron Mediator ◽  
Enzymatic Biosensor ◽  
Current Change ◽  
Chemical Selectivity ◽  
Sweat Lactate ◽  
Change Tendency

A new enzymatic biosensor worn on eyeglasses has been developed for low-noise and noninvasive determination of lactate in human sweat during physical exercise. The Os (osmium)-complex, the electron mediator between the enzyme and the electrode, was first immobilized on a flexibly printed carbon electrode. Then, a gel membrane with the stereoscopic reticular structure of lactate oxidase and horseradish peroxidase was casted on the electrode to form the biosensor. Linearity of the biosensor was observed for up to 25 mM lactate in a phosphate buffered solution of pH 7.0. Chemical selectivity was evaluated by adding common interferent species such as ascorbic acid, glucose and uric acid to the lactate. The negligible current interference indicated excellent discriminatory selectivity of the biosensor. Applied to an analysis of the real sweat lactate dynamics of healthy subjects during cycling exercise, the amperometric profiles of the biosensors reflected changes in sweat lactate that depended on physical exercise intensity. Compared with other reported epidermal biosensors attached to the arm or leg, our biosensor not only exhibited a similar current change tendency but also rarely suffered from deformational interference due to their forehead measurement position. Such a successful application of real-time monitoring of sweat lactate means that eyeglass-bound biosensors hold considerable promise in the physical exercise and biomedical fields.

scholarly journals Characterization of Aerococcus viridans isolated from milk samples from cows with mastitis and manure samples

2015 ◽  
Vol 77 (9) ◽  
pp. 1037-1042 ◽  
Author(s):  
Nobukazu SAISHU ◽  
Kazutaka MORIMOTO ◽  
Hiroshi YAMASATO ◽  
Hiroichi OZAKI ◽  
Toshiyuki MURASE
Keyword(s):  
Milk Samples ◽  
Aerococcus Viridans
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