BioInorganic Reaction Mechanisms最新文献_第9页

Kinetics and Mechanism of the Reactions of Bis(biguanide)copper(II) Ion with Different Amino Acids in Aqueous Media 双(双胍)铜(II)离子在水溶液中与不同氨基酸反应的动力学及机理

BioInorganic Reaction Mechanisms Pub Date : 2000-01-01 DOI: 10.1515/irm-2000-0408

A. Das

{"title":"Kinetics and Mechanism of the Reactions of Bis(biguanide)copper(II) Ion with Different Amino Acids in Aqueous Media","authors":"A. Das","doi":"10.1515/irm-2000-0408","DOIUrl":"https://doi.org/10.1515/irm-2000-0408","url":null,"abstract":"Abstract The kinetics of the reaction of [Cu(bigH)2]2+ (bigH = biguanide) with an excess of different amino acids (LH) like ß-alanine, L-phenylalanine and L-valine in aqueous solution in the 7.60-9.00 pH range at different temperatures (30-40°C) have been studied by stopped-flow spectrophotometry and compared with those of different ligands reacting with the title copper(II) complex. The ligand replacement process has been suggested to pass through an intermediate formation of the ternary complex, [Cu(bigH)L]+ as the rate determining step, followed by the rapid transformation into the binary complex, [CuL2]. The overall ligand replacement process follows a two-term rate law, kobs = k0 + k1Ka[L]T/([H+] + Ka, where [L]T gives the total concentration of the entering ligand, i.e. amino acid, and Κa gives the deprotonation constant of the amino acid (LH). Thus the process experiences both the ligand independent path (i.e. k0) and ligand dependent path (i.e. k0). The solvent assisted k0 path leads to a copper(II) mono-biguanide complex followed by the rapid nucleophilic substitution; the k1 path is in agreement with an associative mechanism. The k0 path is independent of the structure and basicity of the entering amino acids while the k0 path is dependent on the basicity and steric crowding of the entering amino acid. The reactivity order is: glycine > α-alanine > ß-alanine > L-valine > L-phenylalanine. The activation parameters have been evaluated. An iso-kinetic trend for different amino acids and other nucleophiles reacting with the title copper(II) complex has been found to prevail.","PeriodicalId":8996,"journal":{"name":"BioInorganic Reaction Mechanisms","volume":"41 1","pages":"309 - 314"},"PeriodicalIF":0.0,"publicationDate":"2000-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"86547020","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 1

Aquation and Base Hydrolysis of trans-Tetraammine(methylamine)sulfatocobalt(III) Complex Ion 反式四胺(甲胺)硫酸盐钴(III)配合物离子的水化和碱水解

BioInorganic Reaction Mechanisms Pub Date : 2000-01-01 DOI: 10.1515/irm-2000-0410

Fabian Benzo, Alberto L. Capparelll, D. Mártire, B. Sienra

引用次数: 0

Substitution Reactions of Platinum(II) Dipicolinate Complex with Some Mono- and Bidentate Ligands - Rates and Mechanism 铂(II)二吡啶配合物与一些单齿和双齿配体的取代反应-速率和机理

BioInorganic Reaction Mechanisms Pub Date : 2000-01-01 DOI: 10.1515/irm-2000-0405

M. Ray, Sukalpa Dey, P. Banerjee

引用次数: 3

Kinetic and Mechanistic Studies on the Interaction of Inosine with Hydroxopentaaquarhodium(III) Ion 肌苷与羟基戊二钠离子相互作用的动力学和机理研究

BioInorganic Reaction Mechanisms Pub Date : 1999-09-01 DOI: 10.1515/IRM.2005.5.4.255

S. Mukhopadhyay, A. Ghosh

{"title":"Kinetic and Mechanistic Studies on the Interaction of Inosine with Hydroxopentaaquarhodium(III) Ion","authors":"S. Mukhopadhyay, A. Ghosh","doi":"10.1515/IRM.2005.5.4.255","DOIUrl":"https://doi.org/10.1515/IRM.2005.5.4.255","url":null,"abstract":"Kinetics of interacti on between uridine and [Rh(H10 )sOHf+ has been studied spectrophotometrically as a functi o n of [Rh(HzO)sOH 2 +] , [uridine] , pH and temperature. The reacti on has been monitored at 290 nm, the Amax of the substituted complex and where spectral difference between the reactant and product is maximum. The reaction rate increases with [uri dine] and reaches limiting value at higher ligand concentration. From the experimental findings an associative interchange mechanism for the substitution process is suggested. The activation parameters (t<.f{' = 46.5 ± 1.4 kJ mort, t<.S ~ =-181 ± 4 J K-'mor') support the proposition. The negative t<.C\" (-15.1 kJ mort) for the first equilibrium step al so supports the sponta neous formation of an outersphere association complex. Platinum complexes, particularly cis-platin, a pure inorganic compound, exhibit powerful anticancer properties l . 2 . Because of it's toxicity the search for other alternatives continued in other 3d, 4d and 5d metal ions 3 - 6 . It is now established 7 that cis-platin is first hydro lysed in biological conditions and the aqua variety is the active species. Some of the products of hydrolysis are responsible for toxicity. Thus it is expected that the aqua complexes, if used directly, will be less toxic. ]n order to examine the bioactivity of rho dium(IIl) complexes we have already reported studies on the interaction of rhodium(lII) with pyridine-2Id . 8 dl h\" 9 I . 10 d . II a oxtme, -met 10nIne, -cysteme , a enosme and cytidine l2 . Tn this paper the interaction of uridine with hydroxopentaaquarhodium(1J1) ion in aqueous medium is reported.","PeriodicalId":8996,"journal":{"name":"BioInorganic Reaction Mechanisms","volume":"57 1","pages":"255 - 263"},"PeriodicalIF":0.0,"publicationDate":"1999-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"86220849","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 3

Free Radical Induced Oxidation of L-Cystine by Alkaline Permanganate - A Kinetic Study 碱性高锰酸盐自由基诱导l -胱氨酸氧化动力学研究

BioInorganic Reaction Mechanisms Pub Date : 1999-07-01 DOI: 10.1515/irm-1999-0306

M. R. Kembhavi, R. G. Panari, S. Nandibewoor

引用次数: 2

The Hydrolysis Kinetics of ds-diamminedichloroplatinum(II). 10. Activation Volumes for Halide Anation of Some czs-[Pt(N)2(OH2)2]2+ Systems ds-二胺二氯铂的水解动力学(II)。10. 某些cz -[Pt(N)2(OH2)2]2+体系卤化活化体积

BioInorganic Reaction Mechanisms Pub Date : 1999-04-01 DOI: 10.1515/irm-1999-0204

K. Hindmarsh, D. A. House, R. Eldik

{"title":"The Hydrolysis Kinetics of ds-diamminedichloroplatinum(II). 10. Activation Volumes for Halide Anation of Some czs-[Pt(N)2(OH2)2]2+ Systems","authors":"K. Hindmarsh, D. A. House, R. Eldik","doi":"10.1515/irm-1999-0204","DOIUrl":"https://doi.org/10.1515/irm-1999-0204","url":null,"abstract":"Abstract For the following equations relating to the aquation and anation processes of cisplatin and similar squareplanar platinum(II) diamine complexes: rate constant (k-2, Μ-1 s-1,25°C), activation enthalpy (ΔΗ#, kJ mol-1) , activation entropy (ΔS#, JΚ-1 mol-1) and activation volume (ΔV#, cm3 mol-1) data have been found for the bromide anation of cis- [Pt(N)2(OH2)2]2+ where (N)2 = tn, en, cis-(NH3)2, trans-(NH3)2, Me2tn, chxn; CJS-(NH3)2: k-2 = 0.45, ΔH# = 68, ΔS# = -25, trans-(NH3)2: 4.23,56, -44, chxn: 1.13, 70, -9, Me2tn: 1.53, 65, -24, en: 1.29, 71, -5, ΔV# = -5.3, tn: 1.86,68, -12, ΔV# = -7.4. Further activation volumes (ΔV#, cm3 mol-1) have been determined for selected k-1 and k-2 bromide or chloride anation data. k-1(cm3 mol-1, CI-): en -7.4. k-1(cm3 mol-1, Br-): cis-(NH3)2-11, en -9.4, tn -7.66. k-2(cm3 mol-1, CI-): cis-(NH3)2-5.1, en -5.7, tn -5.8. For all kx above where ΔV# has been measured, values lie in the range -4 to -11 cm3 mol-1 and apart from two exceptions ΔS# is negative in 36 cases implying an associative mechanism for the substitution process at square-planar platinum(II) centres.","PeriodicalId":8996,"journal":{"name":"BioInorganic Reaction Mechanisms","volume":"87 1","pages":"107 - 120"},"PeriodicalIF":0.0,"publicationDate":"1999-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"81214998","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 2

Complexation of Pendant Arm Macrocycles with Cu(II) Hydroxo Complexes in Strongly Alkaline Solutions. Investigation of pH Dependences 悬垂臂大环与Cu(II)羟基配合物在强碱性溶液中的络合作用。pH依赖性研究

BioInorganic Reaction Mechanisms Pub Date : 1999-04-01 DOI: 10.1515/irm-1999-0209

P. Lye, G. Lawrance, M. Maeder

引用次数: 1

Kinetics of Dissociation of the Cobalt(II) and Copper(II) Complexes of 2,2′,2″-tris(monomethylamino)triethylamine in Aqueous Acidic Solution 钴(II)和铜(II)配合物2,2 '，2″-三(一甲基胺)三乙胺在酸性水溶液中的解离动力学

BioInorganic Reaction Mechanisms Pub Date : 1999-04-01 DOI: 10.1515/irm-1999-0202

F. Thaler, C. Hubbard, R. Eldik

{"title":"Kinetics of Dissociation of the Cobalt(II) and Copper(II) Complexes of 2,2′,2″-tris(monomethylamino)triethylamine in Aqueous Acidic Solution","authors":"F. Thaler, C. Hubbard, R. Eldik","doi":"10.1515/irm-1999-0202","DOIUrl":"https://doi.org/10.1515/irm-1999-0202","url":null,"abstract":"Abstract The stability constant of the complex formed between cobalt(II) and trimethyltren (Me3tren), 2,2′,2″-triaminotriethylamine monomethylated on each terminal amino group, in aqueous medium was determined (log Κ = 12.10 ± 0.01 at 25.0° C and ionic strength of 1.0 mol dm-3 (NaClO4)). The deprotonation constant of the aqua complex, [Co(Me3tren)(H2O)]2+, was also established (pKa = 9.31 ± 0.02 under the same conditions). It is concluded on the basis of these values and properties such as the UV/vis spectrum, that the complex possesses trigonal bipyramidal geometry, as does the corresponding copper(II) complex. Dissociation of both complexes, as a function of aqueous acid concentration, was monitored spectrophotometrically. For the copper(II) system there is a modest dependence on the acid concentration when [H+] < 0.4 mol dm-3 , and above this value the reaction is independent of acid concentration, with the firstorder rate constant reaching a limiting value of about 100 s-1 at 25.0°C. Dissociation of the cobalt(II) complex does not depend on the acid concentration and occurs at a rate of 34 s-1 . A mechanism accounting for these findings is proposed, and the rate and activation parameters are discussed in terms of the dissociation of other trigonal bipyramidal complexes.","PeriodicalId":8996,"journal":{"name":"BioInorganic Reaction Mechanisms","volume":"82 1","pages":"83 - 90"},"PeriodicalIF":0.0,"publicationDate":"1999-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"84396245","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 1

Kinetics and Mechanisms of the Reaction of Aluminium(III) with Polyaminocarboxylic Acids 铝(III)与聚氨基羧酸反应的动力学和机理

BioInorganic Reaction Mechanisms Pub Date : 1999-04-01 DOI: 10.1515/irm-1999-0207

Claire Τ. Tomany, M. Hynes

引用次数: 2

The Influence of Steric Effects on the Oxidation Kinetics of [FeII(aminopolycarboxylato)] Complexes with Dioxygen 位阻效应对FeII(氨基聚羧酸)配合物氧化动力学的影响

BioInorganic Reaction Mechanisms Pub Date : 1999-04-01 DOI: 10.1515/irm-1999-0203

S. Seibig, R. Eldik

引用次数: 3