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1.
J Artif Organs ; 26(1): 84-88, 2023 Mar.
Article in English | MEDLINE | ID: mdl-35731429

ABSTRACT

In Japan, successful cases of a bridge to lung transplantation (BTT) by extracorporeal membrane oxygenation (ECMO) are rare. We present the case of a man in his thirties, diagnosed with interstitial pneumonia 6 years prior and registered for lung transplant 1 year prior due to disease progression despite treatment. Due to the patient's worsening respiratory failure, he was transferred to our hospital for BTT by ECMO. Since long-term management was expected and pulmonary hypertension was present, veno-arterial (V-A) ECMO was conducted using the right atrial blood outflow via the right internal jugular vein and right axillary artery inflow via a vascular graft. After tracheostomy, he was managed as "Awake ECMO". In addition, interprofessional collaboration such as physiotherapist rehabilitation, nurses, and liaison teams prevented muscle weakness and supported the mental aspect. We were able to minimize complications such as severe infections and bleeding. A compatible brain-dead donor was found on day 108 after introducing ECMO, and the patient was transferred to a transplant facility on day 109. The peripheral upper V-A ECMO is one of the configurations suitable for long-term BTT management.


Subject(s)
Extracorporeal Membrane Oxygenation , Lung Diseases, Interstitial , Lung Transplantation , Respiratory Insufficiency , Male , Humans , Extracorporeal Membrane Oxygenation/methods , Respiratory Insufficiency/therapy , Brain
2.
J Intensive Care ; 12(1): 5, 2024 Jan 26.
Article in English | MEDLINE | ID: mdl-38273416

ABSTRACT

BACKGROUND: Chest computed tomography findings are helpful for understanding the pathophysiology of severe acute respiratory distress syndrome (ARDS). However, there is no large, multicenter, chest computed tomography registry for patients requiring veno-venous extracorporeal membrane oxygenation (V-V ECMO). The aim of this study was to describe chest computed tomography findings at V-V ECMO initiation and to evaluate the association between the findings and outcomes in severe ARDS. METHODS: This multicenter, retrospective cohort study enrolled patients with severe ARDS on V-V ECMO, who were admitted to the intensive care units of 24 hospitals in Japan between January 1, 2012, and December 31, 2022. RESULTS: The primary outcome was 90-day in-hospital mortality. The secondary outcomes were the successful liberation from V-V ECMO and the values of static lung compliance. Among the 697 registry patients, of the 582 patients who underwent chest computed tomography at V-V ECMO initiation, 394 survived and 188 died. Multivariate Cox regression showed that traction bronchiectasis and subcutaneous emphysema increased the risk of 90-day in-hospital mortality (hazard ratio [95% confidence interval] 1.77 [1.19-2.63], p = 0.005 and 1.97 [1.02-3.79], p = 0.044, respectively). The presence of traction bronchiectasis was also associated with decreased successful liberation from V-V ECMO (odds ratio: 0.27 [0.14-0.52], p < 0.001). Lower static lung compliance was associated with some chest computed tomography findings related to changes outside of pulmonary opacity, but not with the findings related to pulmonary opacity. CONCLUSIONS: Traction bronchiectasis and subcutaneous emphysema increased the risk of 90-day in-hospital mortality in patients with severe ARDS who required V-V ECMO.

3.
BMJ Open ; 13(10): e072680, 2023 10 18.
Article in English | MEDLINE | ID: mdl-37852764

ABSTRACT

INTRODUCTION: While limiting the tidal volume to 6 mL/kg during veno-venous extracorporeal membrane oxygenation (V-V ECMO) to ameliorate lung injury in patients with acute respiratory distress syndrome (ARDS) is widely accepted, the best setting for positive end-expiratory pressure (PEEP) is still controversial. This study is being conducted to investigate whether a higher PEEP setting (15 cmH2O) during V-V ECMO can decrease the duration of ECMO support needed in patients with severe ARDS, as compared with a lower PEEP setting. METHODS AND ANALYSIS: The study is an investigator-initiated, multicentre, open-label, two-arm, randomised controlled trial conducted with the participation of 20 intensive care units (ICUs) at academic as well as non-academic hospitals in Japan. The subjects of the study are patients with severe ARDS who require V-V ECMO support. Eligible patients will be randomised equally to the high PEEP group or low PEEP group. Recruitment to the study will continue until a total of 210 patients with ARDS requiring V-V ECMO support have been randomised. In the high PEEP group, PEEP will be set at 15 cmH2O from the start of V-V ECMO until the trials for liberation from V-V ECMO (or until day 28 after the allocation), while in the low PEEP group, the PEEP will be set at 5 cmH2O. Other treatments will be the same in the two groups. The primary endpoint of the study is the number of ECMO-free days until day 28, defined as the length of time (in days) from successful libration from V-V ECMO to day 28. The secondary endpoints are mortality on day 28, in-hospital mortality on day 60, ventilator-free days during the first 60 days and length of ICU stay. ETHICS AND DISSEMINATION: Ethics approval for the trial at all the participating hospitals was obtained on 27 September 2022, by central ethics approval (IRB at Hiroshima University Hospital, C2022-0006). The results of this study will be presented at domestic and international medical congresses, and also published in scientific journals. TRIAL REGISTRATION NUMBER: The Japan Registry of Clinical Trials jRCT1062220062. Registered on 28 September 2022. PROTOCOL VERSION: 28 March 2023, version 4.0.


Subject(s)
Extracorporeal Membrane Oxygenation , Respiratory Distress Syndrome , Humans , Positive-Pressure Respiration/methods , Respiratory Distress Syndrome/therapy , Tidal Volume , Ventilators, Mechanical , Randomized Controlled Trials as Topic , Multicenter Studies as Topic
4.
Am J Crit Care ; 30(1): 55-63, 2021 01 01.
Article in English | MEDLINE | ID: mdl-33385201

ABSTRACT

BACKGROUND: Iliopsoas hematoma occasionally occurs in patients receiving anticoagulation therapy. It may be a life-threatening complication and can cause disseminated intravascular coagulation, which could develop into abdominal compartment syndrome. The incidence of and factors associated with iliopsoas hematoma during venovenous extracorporeal membrane oxygenation (ECMO) have not been well studied. OBJECTIVES: To describe the incidence of iliopsoas hematoma and associated factors among patients undergoing venovenous ECMO. METHODS: A retrospective cohort study was conducted at Nippon Medical School Hospital from April 2015 to October 2018. All patients (>18 years old) with iliopsoas hematoma received a diagnosis based on computed tomography. RESULTS: During the study period, 54 patients were supported with venovenous ECMO. Iliopsoas hematoma occurred in 8 of those patients (15%), none of whom had disseminated intravascular coagulopathy or abdominal compartment syndrome develop. Univariate analysis indicated that management of ECMO while the patient was awake and mobilization beyond sitting on the edge of the bed were significantly different (P < .05) in patients with and patients without iliopsoas hematoma. Mortality, however, did not differ significantly between the 2 groups. CONCLUSIONS: Our findings emphasize that recognizing factors associated with iliopsoas hematoma and detecting them early are crucial during venovenous ECMO in order to treat patients with iliopsoas hematoma appropriately.


Subject(s)
Extracorporeal Membrane Oxygenation , Hematoma , Extracorporeal Membrane Oxygenation/adverse effects , Hematoma/diagnostic imaging , Hematoma/etiology , Hematoma/therapy , Humans , Retrospective Studies
5.
Biosci Biotechnol Biochem ; 73(3): 524-9, 2009 Mar 23.
Article in English | MEDLINE | ID: mdl-19270386

ABSTRACT

Quinohemoprotein amine dehydrogenase (QH-AmDH) from Paracoccus denitrificans is an alphabetagamma heterotrimeric enzyme catalyzing oxidative deamination of amines with large substitutes, such as butylamine and benzylamine. The smallest gamma subunit has cross-linking cysteine tryptophylquinone (CTQ) as a catalytic center. A hemoprotein similar to QH-AmDH in molecular mass, subunit structure, and UV-vis spectral property, but having no enzymatic activity, was isolated. The enzymatically silent form (sQH-AmDH) was activated slowly by the substrates of QH-AmDH, and quickly by reductants, dithionite and dithiothreitol. Electrolysis of sQH-AmDH yielded the active form at potentials more negative than -0.17 V (vs. SHE). The activated protein reacted with a carbonyl reagent, 4-nitrophenylhydrazine, giving a typical spectrum of 4-nitrophenylhydrazone, while sQH-AmDH did not give such a spectrum. The gamma subunit of sQH-AmDH showed a sharp peak at 390 nm in UV-vis spectrum clearly distinguishable from that of QH-AmDH. Electrospray ionization mass spectrometric analysis showed that the molecular mass of the gamma subunit of sQH-AmDH was larger than that of QH-AmDH by 15.6. The data suggest that the CTQ-like moiety of sQH-AmDH is an oxime. This hypothesis was confirmed by subsequent hydroxylamine treatment of QH-AmDH. QH-AmDH was treated with hydroxylamine yielding an oxime derivative. The UV-vis spectral properties of the gamma subunit of hydroxylamine-treated QH-AmDH were identical to those of sQH-AmDH. The hydroxylamine-treated QH-AmDH was also reactivated by butylamine, as in the case of sQH-AmDH.


Subject(s)
Oxidoreductases Acting on CH-NH Group Donors/chemistry , Oxidoreductases Acting on CH-NH Group Donors/metabolism , Paracoccus denitrificans/enzymology , Absorption , Amines/pharmacology , Electrolysis , Enzyme Activation/drug effects , Hemeproteins/chemistry , Hemeproteins/metabolism , Hydrazones/chemistry , Hydrazones/pharmacology , Hydrogen-Ion Concentration , Reducing Agents/pharmacology , Spectrophotometry, Ultraviolet
6.
Anal Sci ; 24(2): 237-41, 2008 Feb.
Article in English | MEDLINE | ID: mdl-18270415

ABSTRACT

The thermal stability of a redox enzyme, bilirubin oxidase (BOD), has been quantitatively evaluated by measuring the inactivation kinetics of BOD at several temperatures. The enzyme activity is directly related to the mediated bioelectrocatalytic current for the BOD-catalyzed reduction of O(2). Thus, the inactivation process is measured by the time-dependent decrease in the bioelectrocatalytic current. The results reveal that the inactivation obeys first-order kinetics, whose rate constants (k) are determined at pH 7.0 and at 50 - 70 degrees C. The half life of BOD activity, calculated from the k value at 50 degrees C is 114 min, which is in harmony with the thermal-stability data given in a catalog by Amano Enzyme Inc. The bioelectrocatalysis method allows in situ measurements of the inactivation kinetics in the period of a few minutes at relatively high temperatures. The rate constants show a large temperature dependence, leading to a large Arrhenius activation energy (E(A)) of 221 kJ mol(-1). The activation Gibbs energy (DeltaG(not equal)), activation enthalpy (DeltaH(not equal)), and activation entropy (DeltaS(not equal)) are also determined.


Subject(s)
Biosensing Techniques/methods , Oxidoreductases Acting on CH-CH Group Donors/analysis , Temperature , Biosensing Techniques/instrumentation , Catalysis , Electrochemistry , Enzyme Stability , Kinetics , Oxidation-Reduction , Oxygen/chemistry , Protein Denaturation , Reproducibility of Results , Sensitivity and Specificity , Time Factors
7.
Bioelectrochemistry ; 69(1): 74-81, 2006 Sep.
Article in English | MEDLINE | ID: mdl-16431164

ABSTRACT

Bioelectrocatalytic oxidation of acetate was investigated under anaerobic conditions by using Escherichia coli K-12 (IFO 3301) cells cultured on aerobic media containing poly-peptone, glucose or acetate as the sole carbon source. It was found that all E. coli cells cultured on the three media work as good catalysts of the electrochemical oxidation of acetate as well as glucose with Fe(CN)6(3-), 2,3-dimethoxy-5-methyl-1,4-benzo-quinone (Q0), 2,6-dichloro-indophenol, or 2-methyl-1,4-naphthoquinone as artificial electron acceptors (mediators). Acetate-grown E. coli cells exhibited the highest relative activity of the acetate oxidation against the glucose oxidation. On the other hand, all the artificial electron acceptors used work as inhibitors for the catalytic oxidation of acetate at increased concentrations. The inhibition phenomenon can be interpreted in terms of competitive substrate inhibition as a whole. Apparent values of Michaelis constant, catalytic constant, and inhibition constant were evaluated by amperometric methods. Q0 is an effective artificial mediator as evidenced by a large reaction rate constant between the cell and Q0 at least at low concentrations (<50 microM). However, Fe(CN)6(3-) is a promising mediator in biosensor applications because the inhibition constant is very large and it works as an electron acceptor even under aerobic conditions.


Subject(s)
2,6-Dichloroindophenol/chemistry , Acetates/chemistry , Acetates/metabolism , Benzoquinones/chemistry , Escherichia coli/metabolism , Ferrocyanides/chemistry , Vitamin K 3/chemistry , Catalysis , Electrochemistry , Escherichia coli/chemistry , Escherichia coli/cytology , Glucose/chemistry , Kinetics , Oxidation-Reduction , Peptones/chemistry
8.
Biochim Biophys Acta ; 1647(1-2): 121-6, 2003 Apr 11.
Article in English | MEDLINE | ID: mdl-12686120

ABSTRACT

Electrochemical studies on the applied aspects of quinoproteins are briefly reviewed. Catalytic reactions of quinoprotein enzymes can be connected to electrochemical reactions directly or by the mediation of molecules functioning as electron acceptors of the enzymes. Such an enzyme-electrochemical reaction is called bioelectrocatalysis. It provides a novel method of kinetic analysis of enzyme catalysis and even whole bacterial cell catalysis. The principle of bioelectrocatalysis is first described, then, the bioelectrocatalysis-based application of quinoproteins in biosensors is mentioned. Characteristics and performance of this type of biosensor is explained by citing our own work. Possible application in bioreactors and biofuel cells is also mentioned.


Subject(s)
Bacteria/metabolism , Biosensing Techniques/methods , Quinolones/metabolism , Quinones/metabolism , Catalysis , Electrochemistry , Electrodes
9.
Biochim Biophys Acta ; 1647(1-2): 289-96, 2003 Apr 11.
Article in English | MEDLINE | ID: mdl-12686147

ABSTRACT

Paracoccus denitrificans produces two primary enzymes for the amine oxidation, tryptophan-tryptophylquinone (TTQ)-containing methylamine dehydrogenase (MADH) and quinohemoprotein amine dehydrogenase (QH-AmDH). QH-AmDH has a novel cofactor, cysteine tryptophylquinone (CTQ) and two hemes c. In this work, the redox potentials of three redox centers in QH-AmDH were determined by a mediator-assisted continuous-flow column electrolytic spectroelectrochemical technique. Kinetics of the electron transfer from QH-AmDH to three kinds of metalloproteins, amicyanin, cytochrome c(550), and horse heart cytochrome c were examined on the basis of the theory of mediated-bioelectrocatalysis. All these metalloproteins work as a good electron acceptor of QH-AmDH and donate the electron to the terminal oxidase of P. denitrificans, which was revealed by reconstitution of the respiratory chain. These properties are in marked contrast with those of MADH, which shows high specificity to amicyanin. These electron transfer kinetics are discussed in terms of thermodynamics and structural property.


Subject(s)
Bacterial Proteins/chemistry , Oxidoreductases Acting on CH-NH Group Donors/chemistry , Paracoccus denitrificans/enzymology , Cytochrome c Group/metabolism , Electron Transport , Kinetics , Oxidation-Reduction , Oxidoreductases Acting on CH-NH Group Donors/metabolism , Protein Subunits
10.
Biochim Biophys Acta ; 1569(1-3): 35-44, 2002 Jan 15.
Article in English | MEDLINE | ID: mdl-11853955

ABSTRACT

A peroxidase-based bioelectrochemical sensor of hydrogen peroxide (H(2)O(2)) and a Clark-type oxygen electrode were applied to continuous monitoring and kinetic analysis of the autoxidation of catechins. Four major catechins in green tea, (-)-epicatechin, (-)-epicatechin gallate, (-)-epigallocatechin, and (-)-epigallocatechin gallate, were used as model compounds. It was found that dioxygen (O(2)) is quantitatively reduced to H(2)O(2). The initial rate of autoxidation is suppressed by superoxide dismutase and H(+), but is independent of buffer capacity. Based on these results, a mechanism of autoxidation is proposed; the initial step is the one-electron oxidation of the B ring of catechins by O(2) to generate a superoxide anion (O(2)(*-)) and a semiquinone radical, as supported in part by electron spin resonance measurements. O(2)(*-) works as a stronger one-electron oxidant than O(2) against catechins and is reduced to H(2)O(2). The semiquinone radical is more susceptible to oxidation with O(2) than fully reduced catechins. The autoxidation rate increases with pH. This behavior can be interpreted in terms of the increase in the stability of O(2)(*-) and the semiquinone radical with increasing pH, rather than the acid dissociation of phenolic groups. Cupric ion enhances autoxidation; most probably it functions as a catalyst of the initial oxidation step of catechins. The product cuprous ion can trigger a Fenton reaction to generate hydroxyl radical. On the other hand, borate ion suppresses autoxidation drastically, due to the strong complex formation with catechins. The biological significance of autoxidation and its effectors are also discussed.


Subject(s)
Antioxidants/chemistry , Catechin/analogs & derivatives , Catechin/chemistry , Benzoquinones/chemistry , Borates/chemistry , Cations, Divalent , Copper/chemistry , Electron Spin Resonance Spectroscopy , Hydrogen Peroxide/chemistry , Hydrogen-Ion Concentration , Models, Chemical , Oxidation-Reduction , Oxygen/chemistry , Quality Control
11.
Biochim Biophys Acta ; 1699(1-2): 65-75, 2004 Jun 01.
Article in English | MEDLINE | ID: mdl-15158713

ABSTRACT

A novel cytochrome c and a catalase-peroxidase with alkaline peroxidase activity were purified from the culture supernatant of Bacillus sp. No.13 and characterized. The cytochrome c exhibited absorption maxima at 408 nm (Soret band) in its oxidized state, and 550 (alpha-band), 521 (beta-band), and 415 (Soret band) nm in its reduced state. The native cytochrome c with a relative molecular mass of 15,000 was composed of two identical subunits. The cytochrome c showed over 50 times higher peroxidase activity than those of known c-type cytochromes from various sources. The optimum pH and temperature of the peroxidase activity were about 10.0 and 70 degrees C, respectively. The peroxidase activity is stable in the pH range of 6.0 to 10.8 (30 degrees C, 1-h treatment), and at temperatures up to 80 degrees C (pH 8.5, 20-min treatment). The heme content was determined to be 1 heme per subunit. The amino acid sequence of the cytochrome c showed high homology with those of the c-type cytochromes from Bacillus subtilis and Bacillus sp. PS3. The catalase-peroxidase showed high catalase activity and considerable peroxidase activity, the specific activities being 55,000 and 0.94 micromol/min/mg, respectively. The optimum pH and temperature of the peroxidase activity were in the range of 6.4 to 10.1 and 60 degrees C, respectively. The catalase-peroxidase showed a lower K(m) value (0.67 mM) as to H(2)O(2) than known catalase-peroxidases.


Subject(s)
Bacillus/enzymology , Bacterial Proteins/isolation & purification , Cytochromes c/isolation & purification , Peroxidases/isolation & purification , Amino Acid Sequence , Bacillus/growth & development , Bacterial Proteins/chemistry , Bacterial Proteins/metabolism , Base Sequence , Cytochromes c/chemistry , Cytochromes c/metabolism , Molecular Sequence Data , Oxidation-Reduction , Peroxidases/chemistry , Peroxidases/metabolism , Protein Subunits , Sequence Homology, Amino Acid
12.
Anal Sci ; 21(12): 1529-31, 2005 Dec.
Article in English | MEDLINE | ID: mdl-16379400

ABSTRACT

The influence of a phospholipid, dipalmitoyl phosphatidylcholine, layer at a nitrobenzenelwater interface on the transfer of tetraethylammonium ion and a polyammonium anti-fungus agent, poly[(dimethylimino)(2-oxo-1,2-ethanediyl)imino1,6-hexanediylimino (1-oxo-1,2-ethanediyl)(dimethylimino)-1,6-hexanediyl] ion, across the interface was studied by normal pulse voltammetry. When the phospholipid was adsorbed to form a monolayer at the nitrobenzenelwater interface by its addition to the organic phase, the half-wave potential in the current vs. potential curves for the transfer of tetraethylammonium ion did not change, but the limiting current was significantly decreased at certain sampling times, indicating a retarding effect of the layer on the ion-transfer. On the other hand, in the current vs. potential curves for the transfer of the polyammonium ion, no significant change in either the half-wave potential or the limiting current was observed upon adding the phospholipid, indicating that the polyammonium ion can easily permeate through the phospholipid layer. The results suggest a new application of the voltammetric technique to the study of cell membrane permeability to polyionic bioactive compounds.

13.
Biosens Bioelectron ; 17(11-12): 993-8, 2002 Dec.
Article in English | MEDLINE | ID: mdl-12392948

ABSTRACT

Escherichia coli cells, which contain apo-glucose dehydrogenase, were used in constructing a mediated amperometric glucose sensor. The E. coli modified glucose sensor, which was prepared by immobilizing E. coli cells behind a dialysis membrane on a carbon paste electrode containing 2,3-dimethoxy-5-methyl-1,4-benzoquinone (Q(0)), produced a current for the electrocatalytic oxidation of glucose with Q(0) as an electron transfer mediator only after the addition of a trace amount of pyrroloquinoline quinone (PQQ), the cofactor of the enzyme. This allows a novel method of glucose measurements free from the interference of the redox active substances, if contained, in a sample solution. The glucose sensor was insensitive to dioxygen; the currents measured under anaerobic and aerobic conditions, and even under dioxygen saturated conditions were almost the same in magnitude at a given concentration of glucose over the range of 0.2-10 mM. Response time of the glucose sensor was 2 min to attain 90% level of the steady-state current. The E. coli modified glucose sensor was reusable when treated with ethylenediaminetetraacetic acid (EDTA). When E. coli cells were lyophilized, they could be stored at room temperature in a dry box for more than six months without loss of the catalytic activity.


Subject(s)
Biofilms , Biosensing Techniques/instrumentation , Electrochemistry/methods , Escherichia coli/metabolism , Glucose Dehydrogenases/metabolism , Glucose/analysis , Biosensing Techniques/methods , Cells, Cultured , Culture Media/metabolism , Electrochemistry/instrumentation , Electrodes , Equipment Design , Glucose/metabolism , Hydrogen-Ion Concentration , Membranes, Artificial , Oxidation-Reduction , PQQ Cofactor , Quality Control , Quinolones/metabolism , Quinones/metabolism , Sensitivity and Specificity , Temperature
14.
Case Rep Hematol ; 2013: 675187, 2013.
Article in English | MEDLINE | ID: mdl-24371530

ABSTRACT

An 84-year-old woman was admitted to our hospital with nonproductive cough and dyspnea on exertion. Computed tomography (CT) scan revealed extensive consolidation in the right lung. She was diagnosed with pulmonary mucosa-associated lymphoid tissue (MALT) lymphoma using CT-guided lung biopsy. Her pulmonary images and respiratory symptoms did not improve two months after receiving 4 cycles of rituximab weekly; therefore, yttrium-90 ibritumomab tiuxetan was chosen as salvage therapy. The abnormal shadow on her pulmonary images was significantly reduced two months later, and she had no symptoms without nonhematological toxicities. She has had no progression for 18 months. Furthermore, radiation pneumonitis has not also been observed. We herein reported bulky pulmonary MALT lymphoma treated with yttrium-90 ibritumomab tiuxetan.

15.
Anal Sci ; 25(6): 825-7, 2009 Jun.
Article in English | MEDLINE | ID: mdl-19531895

ABSTRACT

An amperometric biosensor for the detection of glucosamine (GlcN) and chitosan oligosaccharides ((GlcN)n) was introduced for an activity measurement of chitosanase. By using the biosensor, an increase in the anodic current due to the production of GlcN and (GlcN)n by chitosanase was measured in a chitosan solution. The maximum value of the slope of the current increase was proportional to the enzyme concentration up to 1.4 microg mL(-1). The present method had the advantages of being simple and rapid over the conventional Elson-Morgan method.


Subject(s)
Biosensing Techniques/methods , Glycoside Hydrolases/metabolism , Chitosan/analysis , Electrochemistry , Enzyme Activation , Glucosamine/analysis , Oligosaccharides/analysis
16.
Anal Sci ; 25(9): 1077-81, 2009 Sep.
Article in English | MEDLINE | ID: mdl-19745533

ABSTRACT

It has been shown that polyammonium cations comprising quaternary ammonium and hydrophilic groups such as amide and hydroxyl groups stabilize a redox enzyme bilirubin oxidase (BOD). The BOD catalyzes the reaction: 4[Fe(CN)6]4- + 4H+ + O2 --> 4[Fe(CN)6]3- + 2H2O, and has been a promising enzyme for use as a cathode catalyst in biofuel cells. In this study, the stabilizing effect of poly[oxyethylene(dimethylimino)propyl(dimethylimino)ethylene] (PA1) on BOD has been investigated. The sample solution containing BOD and the PA1 salt was kept at a given temperature, and the loss of the enzymatic activity was detected after given stored times. The activity decreased exponentially with stored time so that the first-order rate-constant of inactivation was determined. The inactivation rate-constant lowered with increasing the concentration of the PA1 salt, suggesting that BOD was stabilized by the association with the PA1 cation. The PA1 cation may act like a protective colloid or decrease the local disorder of BOD by its wrapping. A membrane-covered electrode containing BOD, PA1, and [Fe(CN)6](4-/3-) in the internal solution phase was examined in air-saturated aqueous solution. The electrode gave a well-defined current-potential curve with a steady state limiting current due to the PA1-[Fe(CN)6](4-/3-) polyion complex-mediated bioelectrocatalytic current for the reduction of O2. The decreasing of the steady state limiting current became slower in the presence of the PA1 salt, indicating again the stabilizing effect of PA1 cation on BOD.


Subject(s)
Enzymes, Immobilized/chemistry , Oxidoreductases Acting on CH-CH Group Donors/chemistry , Polymers/pharmacology , Electric Conductivity , Electrochemistry , Electrodes , Enzyme Stability/drug effects , Enzymes, Immobilized/metabolism , Ferricyanides/chemistry , Ferricyanides/metabolism , Hypocreales/enzymology , Membranes, Artificial , Oxidoreductases Acting on CH-CH Group Donors/metabolism , Water/chemistry
17.
Anal Sci ; 25(11): 1283-8, 2009 Nov.
Article in English | MEDLINE | ID: mdl-19907083

ABSTRACT

The inactivation of a redox enzyme, bilirubin oxidase (BOD), by heat and guanidine hydrochloride (GuHCl) was studied by two bioelectrochemical methods. One is a conventional method, which measures the inactivation of BOD in solution, and the other is a method using a BOD-immobilized electrode (a membrane/BOD/GC electrode), which measures the inactivation of BOD in the immobilized state. The results for thermal inactivation revealed that BOD both in solution and in the immobilized state obeyed the same irreversible inactivation kinetics. The CD and absorption spectra of BOD confirmed that the irreversible thermal inactivation was accompanied by a change in the secondary structure and the dissociation of type-1 copper from BOD. The measurements in the presence of GuHCl demonstrated that the BOD activity was significantly decreased at 1 M GuHCl in both states, and that the decrease proceeded reversibly. The CD spectrum of BOD indicated that the secondary structure of BOD was little affected by GuHCl at this concentration. The effect of GuHCl on the thermal inactivation was studied and evaluated as the resulting values of the Arrhenius activation energy: DeltaG(not equal), DeltaH(not equal), and DeltaS(not equal).


Subject(s)
Biocatalysis , Oxidoreductases Acting on CH-CH Group Donors/chemistry , Oxidoreductases Acting on CH-CH Group Donors/metabolism , Electrochemistry , Enzyme Activation/drug effects , Enzymes, Immobilized/chemistry , Enzymes, Immobilized/metabolism , Guanidine/pharmacology , Hypocreales/enzymology , Oxidation-Reduction , Protein Denaturation/drug effects , Temperature
18.
Anal Sci ; 24(11): 1415-9, 2008.
Article in English | MEDLINE | ID: mdl-18997368

ABSTRACT

Cyclic voltammograms of the aqueous solution containing polyammonium cations and the [Fe(CN)6]4-. anion at a plastic-formed carbon or platinum electrode were recorded. Polyammonium salts comprising quaternary ammonium in the main chain or sub chain and those comprising primary ammonium were tested. Under certain conditions, well-developed anodic and cathodic peak currents with the midpoint potentials different from that when the polyammonium cation is absent, that is, the midpoint potential of [Fe(CN)6]3- + e- = [Fe(CN)6]4- were exhibited, indicating that the [Fe(CN)6]4-/3- anionic species associate with the polyammonium cations tested to form the polycation-[Fe(CN)6]4-/3- complex species. The polycation complex species can be easily localized around the electrode surface with a dialysis membrane. An application of the polycation complex species as an electron-transfer mediator in the catalytic electrode with a redox enzyme was examined.


Subject(s)
Biosensing Techniques/methods , Electrodes , Enzymes, Immobilized , Ferrocyanides/chemistry , Polyamines/chemistry , Electrochemistry/methods , Oxidation-Reduction , Polyelectrolytes , Quaternary Ammonium Compounds
19.
Anal Sci ; 24(11): 1421-4, 2008.
Article in English | MEDLINE | ID: mdl-18997369

ABSTRACT

Bilirubin oxidase was stored in the solutions containing polyammonium salts for a given time at 30 degrees C, and the activity was assayed. The enzyme catalyzes the reaction: 4[Fe(CN)6]4- + 4H+ + O2 --> 4[Fe(CN)6]3- + 2H2O, and the activity can be measured by the absorbance at the wavelength for the absorption maxima of [Fe(CN)6)]3-. The results show that polyammonium cations comprising quaternary ammonium in the main chain and hydrophilic groups, such as hydroxyl and amide groups, stabilize the enzyme in solution. These polyammonium cations may act like a protective colloid. The membrane-covered electrode containing the polyammonium cations, the enzyme, and [Fe(CN)6]4-/3- in the internal solution phase was constructed. The electrode gave a well-defined current-potential curve with a steady state limiting current due to the polycation-[Fe(CN)6]4-/3- complex-mediated bioelectrocatalytic current for the reduction of O2. The time-dependent decrease of the limiting current indicates again the stabilizing effect of the polyammonium cations on the enzyme.


Subject(s)
Biosensing Techniques/methods , Electrodes , Enzymes, Immobilized , Oxidoreductases Acting on CH-CH Group Donors/analysis , Polyamines/chemistry , Electrochemistry , Enzyme Stability , Oxidation-Reduction , Oxidoreductases Acting on CH-CH Group Donors/metabolism , Polyelectrolytes , Quaternary Ammonium Compounds/chemistry
20.
Biosci Biotechnol Biochem ; 71(4): 946-50, 2007 Apr.
Article in English | MEDLINE | ID: mdl-17420602

ABSTRACT

The kinetics of glucoamylase-catalyzed hydrolysis of starch granules from six different botanical sources (rice, wheat, maize, cassava, sweet potato, and potato) was studied by the use of an electrochemical glucose sensor. A higher rate of hydrolysis was obtained as a smaller size of starch granules was used. The adsorbed amount of glucoamylase on the granule surface per unit area did not vary very much with the type of starch granules examined, while the catalytic constants of the adsorbed enzyme (k(0)) were determined to be 23.3+/-4.4, 14.8+/-6.0, 6.2+/-1.8, 7.1+/-4.1, 4.6+/-3.0, and 1.6+/-0.6 s(-1) for rice, wheat, maize, cassava, sweet potato, and potato respectively, showing that k(0) was largely influenced by the type of starch granules. A comparison of the k(0)-values in relation to the crystalline structure of the starch granules suggested that k(0) increases as the crystalline structure becomes dense.


Subject(s)
Glucan 1,4-alpha-Glucosidase/metabolism , Plants/chemistry , Starch/metabolism , Algorithms , Biosensing Techniques , Electrochemistry , Glucose/biosynthesis , Hydrolysis , Indicators and Reagents , Kinetics , Particle Size , Powders , X-Ray Diffraction
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