Kinetics of Reduction of Toluidine Blue with Sulfite—Kinetic Salt Effect in Elucidation of Mechanism

Jonnalagadda, Sreekantha B.; Gollapalli, Nageswara Rao

doi:10.1021/ed077p506

Cited by 22 publications

(17 citation statements)

References 1 publication

Supporting

Mentioning

Contrasting

Order By: Relevance

“…During reaction, bromide ion, a reaction intermediate plays a dual role, both as the auto catalyst and as an inhibitor giving raise to the complex reaction mechanism. In the Belousov-Zhabotinskii type chemical systems, bromide ion, which switches between high and low concentration conditions acts as control intermediate [23,24] In the MV + and acidic bromate system, in the absence of initially added bromide, the induction time reflects the time required for the accumulation of HBrO 2 and the removal of trace inhibiting species, including bromide, present as impurities with bromate. The ratelimiting step in such system is direct reaction between MV + and BrO 3 -in presence of acid, which is followed by the formation of BrO 2…”

Section: Resultsmentioning

confidence: 99%

Easy to use program “Simkine3” for simulating kinetic profiles of multi-step chemical Systems and optimisation of predictable rate coefficients therein

Shezi¹,

Jonnalagadda²

2012

Bull. Chem. Soc. Eth.

View full text Add to dashboard Cite

ABSTRACT. 'Simkine3', a Delphi based software is developed to simulate the kinetic schemes of complex reaction mechanisms involving multiple sequential and competitive elementary steps for homogeneous and heterogeneous chemical reactions. Simkine3 is designed to translate the user specified mechanism into chemical first-order differential equations (ODEs) and optimise the estimated rate constants in such a way that simulated curves match the experimental kinetic profiles. TLSoda which uses backward differentiation method is utilised to solve resulting ODEs and Downhill Simplex method is used to optimise the estimated rate constants in a robotic way. An online help file is developed using HelpScrible Demo to guide the users of Simkine3. The versatility of the software is demonstrated by simulating the complex reaction between methylene violet and acidic bromate, a reaction which exhibits complex nonlinear kinetics. The new software is validated after testing it on a 19-step intricate mechanism involving 15 different species. The kinetic profiles of multiple simulated curves, illustrating the effect of initial concentrations of bromate, and bromide were matched with the corresponding experimental curves.

show abstract

Section: Resultsmentioning

confidence: 99%

Easy to use program “Simkine3” for simulating kinetic profiles of multi-step chemical Systems and optimisation of predictable rate coefficients therein

Shezi¹,

Jonnalagadda²

2012

Bull. Chem. Soc. Eth.

View full text Add to dashboard Cite

show abstract

“…9A). For a pseudo‐first‐order reaction, the rate constant of dissociation ( k d ) from dodecamer into dimer was estimated at various concentrations of KCl using the Guggenheim method [10]. The k d values in the presence of 0.25 m and 1.0 m KCl were 5.96 and 7.99 s −1 , respectively (Fig.…”

Section: Resultsmentioning

confidence: 99%

“…For a pseudo‐first‐order reaction, a plot of logA vs. time should be linear with a slope of – k t/2.303 based on the following equation: where k is the pseudo‐first‐order rate constant. Thus, rate constants can be calculated from the gradient of the plot [10].…”

Section: Methodsmentioning

confidence: 99%

Dissociation/association properties of a dodecameric cyclomaltodextrinase

et al. 2005

View full text Add to dashboard Cite

Enzymes in biological systems act not only as monomers but also associate to form dimers or higher order oligomers. Dimerization and oligomerization can provide enzymes with a number of functional advantages such as high stability and control over accessibility and specificity of active sites [1,2] As an effort to elucidate the quaternary structure of cyclomaltodextrinase I-5 (CDase I-5) as a function of pH and salt concentration, the dissociation/association processes of the enzyme were investigated under various pH and salt conditions. Previous crystallographic analysis of CDase I-5 indicated that it existed exclusively as a dodecamer at pH 7.0, forming an assembly of six 3D domain-swapped dimeric subunits. In the present study, analytical ultracentrifugation analysis suggested that CDase I-5 was present as a dimer in the pH range of 5.0-6.0, while the dodecameric form was predominant at pH values above 6.5. No dissociation of the dodecamer was observed at pH 7.0 and the above. Gel filtration chromatography showed that CDase I-5 dissociated into dimers at a rate of 8.58 · 10 )2 h )1 at pH 6.0. A mutant enzyme with three histidine residues (H49, H89, and H539) substituted with valines dissociated into dimers faster than the wildtype enzyme at both pH 6.0 and 7.0. The tertiary structure indicated that the effect of pH on dissociation of the oligomer was mainly due to the protonation of H539. Unlike the pH-dependent process, the dissociation of wild-type CDase I-5 proceeded very fast at pH 7.0 in the presence of 0.2-1.0 m of KCl. Stopped-flow spectrophotometric analysis at various concentrations of KCl showed that the rate constants of dissociation (k d ) from dodecamers into dimers were 5.96 s )1 and 7.99 s )1 in the presence of 0.2 m and 1.0 m of KCl, respectively.Abbreviations CD, circular dichroism; CDase, cyclomaltodextrinase; FRET, fluorescence resonance energy transfer; ITC, isothermal titration calorimetry; ThMA, maltogenic amylase from a Thermus strain.

show abstract

“…Toluidine blue is a cationic dye that features a strong absorption band at 531 nm, and is a molecule that can bind, by ionic attraction, to certain negatively charged functional groups of heparin, such as the carboxyl group or the sulfonyl group. 41 Such a binding complex can be separated out from the solution in which the reagents have been placed, and the OD value of the resultant toluidine blue solution was demonstrated to have therefore decreased. If the carboxyl groups of heparins are depleted, it becomes difficult for the heparin molecule to bind with toluidine blue and thus only a small decrease in the OD value of the postcomplex solution occurs as compared with the case where heparin's carboxyl groups remain free.…”

Section: Discussionmentioning

confidence: 99%

Immobilization of NaIO₄‐treated heparin on PEG‐modified 316L SS surface for high anti‐thrombin‐III binding

Chuang

Lin

2007

J Biomedical Materials Res

View full text Add to dashboard Cite

Poor compatibility between blood and metallic coronary artery stents is one reason for arterial restenosis; however, the immobilization of anticoagulant agents on the surface of the stent is a feasible method of improving stent compatibility. Heparin, a well-known anticoagulant, has been frequently used to coat the surfaces of certain biomaterials to attain blood compatibility. The compound 1-ethyl-3-(3-dimethyl-aminopropyl) carbodiimide has often been utilized for the immobilization of heparin, but the critical carboxyl groups of heparin (with regards to heparin's anticoagulant activity) will be reduced by this method. This study examined possible methods of heparin immobilization without consuming these carboxyl groups. The 316L stainless steel surface was first activated with hexamethylene diisocyanate and then coupled with bis-amine-terminated poly (ethylene glycol) (BA-PEG) so as to create active amine groups. Sodium periodate (NaIO(4); SP) was then used to oxidize heparin to form aldehyde groups. The treated heparin could then be grafted onto the activated surface of the test material without losing its carboxyl groups. Effective surface modification of the hexamethylene diisocyanate-activated and BA-PEG-grafted 316L SS surface was confirmed using Fourier Transform Infrared Spectroscopy, electron spectroscopy for chemical analysis and a water contact angle test. After the heparin was immobilized on the BA-PEG-grafted 316L SS surface by SP, the surface showed an improvement in antithrombrin III (AT III) binding ability, its anticoagulant property, and hemocompatibility in comparison with heparin grafted by 1-ethyl-3-(3-dimethyl-aminopropyl) carbodiimide.

show abstract

Kinetics of Reduction of Toluidine Blue with Sulfite—Kinetic Salt Effect in Elucidation of Mechanism

Cited by 22 publications

References 1 publication

Easy to use program “Simkine3” for simulating kinetic profiles of multi-step chemical Systems and optimisation of predictable rate coefficients therein

Easy to use program “Simkine3” for simulating kinetic profiles of multi-step chemical Systems and optimisation of predictable rate coefficients therein

Dissociation/association properties of a dodecameric cyclomaltodextrinase

Immobilization of NaIO₄‐treated heparin on PEG‐modified 316L SS surface for high anti‐thrombin‐III binding

Contact Info

Product

Resources

About

Kinetics of Reduction of Toluidine Blue with Sulfite—Kinetic Salt Effect in Elucidation of Mechanism

Cited by 22 publications

References 1 publication

Easy to use program “Simkine3” for simulating kinetic profiles of multi-step chemical Systems and optimisation of predictable rate coefficients therein

Easy to use program “Simkine3” for simulating kinetic profiles of multi-step chemical Systems and optimisation of predictable rate coefficients therein

Dissociation/association properties of a dodecameric cyclomaltodextrinase

Immobilization of NaIO4‐treated heparin on PEG‐modified 316L SS surface for high anti‐thrombin‐III binding

Contact Info

Product

Resources

About

Immobilization of NaIO₄‐treated heparin on PEG‐modified 316L SS surface for high anti‐thrombin‐III binding