Can metal ions be used as gas-phase disulfide bond cleavage reagents? A survey of coinage metal complexes of model peptides containing an intermolecular disulfide bond

2007 ◽  
Vol 21 (16) ◽  
pp. 2727-2733 ◽  
Author(s):  
Hadi Lioe ◽  
Mubing Duan ◽  
Richard A. J. O'Hair
Keyword(s):  
Metal Ions ◽  
Metal Complexes ◽  
Gas Phase ◽  
Disulfide Bond ◽  
Bond Cleavage ◽  
Coinage Metal ◽  
Intermolecular Disulfide Bond ◽  
Model Peptides

Ion–molecule reactions of transition-metal ions with nitriles in the gas phase: competitive formation of both "end-on" and "side-on" coordination

1991 ◽  
Vol 69 (12) ◽  
pp. 2002-2007 ◽  
Author(s):  
Lin-Zhi Chen ◽  
Jack M. Miller
Keyword(s):  
Metal Ions ◽  
Gas Phase ◽  
Metal Ion ◽  
Alkyl Radical ◽  
Bond Cleavage ◽  
Transition Metal Ions ◽  
Ion Molecule Reactions ◽  
Free Region ◽  
Competitive Coordination ◽  
Field Free Region

First field-free region B/E linked scan studies of metastable and particularly collision-induced dissociations show that two competitive coordination processes ("end-on" and "side-on") exist in the complexation of metal ions (Ni+, Co+, Fe+, and Mn+) with alkanenitriles in the FAB source of an E/B configuration mass spectrometer. Analysis of the B/E linked scan CA spectra gives approximate percentages of the end-on coordination mode in the reactive complexes. An unusual β-methyl migration, involved in the elimination of CH4 from end-on complexes, may be in competition with β-H migration/elimination of H2 and β-C—C bond cleavage/elimination of alkene. For the side-on complexes, the metal ions can insert into various C—C bonds followed by β-H transfer/competitive elimination of alkene and alkane or by a direct C—M+ bond cleavage to give an alkyl radical. Key words: FAB mass spectroscopy, metal-ion/nitrile reactions, collisional activation, coordination modes, ion–molecule reactions.

scholarly journals Spectroscopic Studies and Thermal Analysis of New Azo Dyes Ligands and their Complexes with some Transition of Metal Ions

2018 ◽  
Vol 13 (3) ◽  
pp. 511-523
Author(s):  
Baghdad Science Journal
Keyword(s):  
Metal Ions ◽  
Metal Complexes ◽  
Gas Phase ◽  
General Formula ◽  
Spectroscopic Studies ◽  
Bidentate Ligand ◽  
Tridentate Ligand ◽  
Spectroscopic Techniques ◽  
Vanadium Complex ◽  
1H And 13C Nmr

New Azo ligands HL1 [2-Hydroxy-3-((5-mercapto-1,3,4-thiadiazol-2-yl)diazenyl)-1-naphth aldehyde] and HL2 [3-((1,5-Dimethyl-3-oxo-2-phenyl-2,3-dihydro-1H-pyrazol-4-yl)diazenyl)-2-hydroxy-1-naphthaldehyde] have been synthesized from reaction (2-hydroxy-1-naphthaldehyde) and (5-amino-1,3,4-thiadiazole-2-thiol) for HL1 and (4-amino-1,5-dimethyl-2-phenyl-1H-pyrazol-3(2H)-one) for HL2. Then, its metal ions complexes are synthesized with the general formula; [CrHL1Cl3(H2O)], [VOHL1(SO4)] [ML1Cl(H2O)] where M = Mn(II), Co(II), Ni(II) and Cu(II), and general formula; [Cr(L2)2 ]Cl and [M(L2)2] where M = VO(II), Mn(II), Co(II), Ni(II) and Cu(II) are reported. The ligands and their metal complexes are characterized by phisco- chemical spectroscopic techniques (FT.IR, Mass, UV-Vis, 1H and 13C-NMR, TGA, (C.H.N.), molar conductivity, Atomic Absorbance, Chloride containing magnetic susceptibility). The spectral data suggest that the (HL1) behaves as a bidentate ligand in all complexes, whereas (HL2) behaves as a tridentate ligand for all complexes; bidentate ligand in Vanadium complex is coordinated with the metal ions through azo nitrogen and oxygen atoms. Theoretical studies of these ligands and their metal complexes in gas phase using Hyper chem.8. Studies of these compounds are prepared for their bacterial activity

scholarly journals Mechanisms and energetics of free radical initiated disulfide bond cleavage in model peptides and insulin by mass spectrometry

2015 ◽  
Vol 6 (8) ◽  
pp. 4550-4560 ◽  
Author(s):  
Chang Ho Sohn ◽  
Jinshan Gao ◽  
Daniel A. Thomas ◽  
Tae-Young Kim ◽  
William A. Goddard III ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
Free Radical ◽  
Disulfide Bond ◽  
Bond Cleavage ◽  
Radical Substitution ◽  
Model Peptides

Direct radical substitution at sulfur initiates disulfide bond cleavage by hydrogen-deficient radicals in peptides and proteins.

Synthesis, Characterization and in vitro Biological Evaluation of a New Schiff Base Derived from Drug and its Complexes with Transition Metal Ions

2018 ◽  
Vol 69 (7) ◽  
pp. 1678-1681
Author(s):  
Amina Mumtaz ◽  
Tariq Mahmud ◽  
M. R. J. Elsegood ◽  
G. W. Weaver
Keyword(s):  
Schiff Base ◽  
Transition Metal ◽  
Metal Ions ◽  
Metal Complexes ◽  
Transition Metal Complexes ◽  
Free Ligand ◽  
Transition Metal Ions ◽  
Biological Evaluation ◽  
Pyridoxal Hydrochloride

New series of copper (II), cobalt (II), zinc (II), nickel (II), manganese (II), iron (II) complexes of a novel Schiff base were prepared by the condensation of sulphadizine and pyridoxal hydrochloride. The ligand and metal complexes were characterized by utilizing different instrumental procedures like microanalysis, thermogravimetric examination and spectroscopy. The integrated ligand and transition metal complexes were screened against various bacteria and fungus. The studies demonstrated the enhanced activity of metal complexes against reported microbes when compared with free ligand.

The effect of partial exchange of sulphonated macroporous styrene-divinylbenzene copolymers for different ions on their catalytic activity

1981 ◽  
Vol 46 (10) ◽  
pp. 2354-2363 ◽  
Author(s):  
Svatomír Kmošták ◽  
Karel Setínek
Keyword(s):  
Catalytic Activity ◽  
Transition Metal ◽  
Metal Ions ◽  
Gas Phase ◽  
Transition Metal Ions ◽  
Exchange Capacity ◽  
Total Exchange Capacity ◽  
Styrene Divinylbenzene ◽  
Na Ions ◽  
Type Of Transition

The catalytic activity of sulphonated macroporous styrene-divinylbenzene copolymers, the exchange capacity of which was neutralized from 30, 50 and 80% by Fe(III) ions and from 30% by Na ions and that of Wofatit Y-37 ion exchanger neutralized from 10% of its total exchange capacity by several transition metal ions and by sodium has been studied in isomerisation of cyclohexene and dehydration of 1-propanol in the gas phase at 130 °C. It was demonstrated that in both reactions transition metal ions exhibit additional effect to the expected neutralization of the polymer acid groups. In the case of cyclohexene isomerization, this effect depends on the degree of crosslinking of polymer mass of the catalyst. Such dependence has not been, however, observed in dehydration of 1-propanol. The type of transition metal ions did not exhibit any significant effect on the catalytic activity of the polymer catalysts studied.

scholarly journals A comprehensive analysis of novel disulfide bond introduction site into the constant domain of human Fab

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Hitomi Nakamura ◽  
Moeka Yoshikawa ◽  
Naoko Oda-Ueda ◽  
Tadashi Ueda ◽  
Takatoshi Ohkuri
Keyword(s):  
Thermal Stability ◽  
Pichia Pastoris ◽  
Protein Stability ◽  
Disulfide Bond ◽  
Binding Activity ◽  
Comprehensive Analysis ◽  
The Other ◽  
Constant Domain ◽  
Intermolecular Disulfide Bond ◽  
Sds Page

AbstractGenerally, intermolecular disulfide bond contribute to the conformational protein stability. To identify sites where intermolecular disulfide bond can be introduced into the Fab’s constant domain of the therapeutic IgG, Fab mutants were predicted using the MOE software, a molecular simulator, and expressed in Pichia pastoris. SDS-PAGE analysis of the prepared Fab mutants from P. pastoris indicated that among the nine analyzed Fab mutants, the F130C(H):Q124C(L), F174C(H):S176C(L), V177C(H):Q160C(L), F174C(H):S162C(L), F130C(H):S121C(L), and A145C(H):F116C(L) mutants mostly formed intermolecular disulfide bond. All these mutants showed increased thermal stability compared to that of Fab without intermolecular disulfide bond. In the other mutants, the intermolecular disulfide bond could not be completely formed, and the L132C(H):F118C(L) mutant showed only a slight decrease in binding activity and β-helix content, owing to the exertion of adverse intermolecular disulfide bond effects. Thus, our comprehensive analysis reveals that the introduction of intermolecular disulfide bond in the Fab’s constant domain is possible at various locations. These findings provide important insights for accomplishing human Fab stabilization.

scholarly journals The Exchange of Cyclometalated Ligands

Molecules ◽  
2021 ◽  
Vol 26 (1) ◽  
pp. 210
Author(s):  
Alexander D. Ryabov
Keyword(s):  
Transition Metal ◽  
Metal Complexes ◽  
Transition Metal Complexes ◽  
Bond Activation ◽  
Bond Cleavage ◽  
Cyclopalladated Complexes ◽  
Derivatives Of ◽  
Cyclometalated Ligand ◽  
Incoming Ligand

Reactions of cyclometalated compounds are numerous. This account is focused on one of such reactions, the exchange of cyclometalated ligands, a reaction between a cyclometalated compound and an incoming ligand that replaces a previously cyclometalated ligand to form a new metalacycle: + H-C*~Z ⇄ + H-C~Y. Originally discovered for PdII complexes with Y/Z = N, P, S, the exchange appeared to be a mechanistically challenging, simple, and convenient routine for the synthesis of cyclopalladated complexes. Over four decades it was expanded to cyclometalated derivatives of platinum, ruthenium, manganese, rhodium, and iridium. The exchange, which is also questionably referred to as transcyclometalation, offers attractive synthetic possibilities and assists in disclosing key mechanistic pathways associated with the C–H bond activation by transition metal complexes and C–M bond cleavage. Both synthetic and mechanistic aspects of the exchange are reviewed and discussed.

scholarly journals Carbonic Anhydrase Inhibitors Part 721 Synthesis and Antiglaucoma Properties of Metal Complexes of p-Fluorobenzolamide

1999 ◽  
Vol 6 (2) ◽  
pp. 67-73 ◽  
Author(s):  
Claudiu T. Supuran ◽  
Andrea Scozzafava ◽  
Luca Menabuoni ◽  
Francesco Mincione ◽  
Fabrizio Briganti ◽  
...  
Keyword(s):  
Intraocular Pressure ◽  
Carbonic Anhydrase ◽  
Metal Ions ◽  
Metal Complexes ◽  
Carbonic Anhydrase Inhibitors ◽  
Physico Chemical ◽  
New Compounds

Metal complexes of a heterocyclic sulfonamides possessing very strong carbonic anhydrase (CA) inhibitory properties, i.e., 5-(p-fluorobenzenesulfonylamido)-1,3,4-thiadiazole-2-sulfonamide (p-fluorobenzolamide) were prepared. The new complexes contained metal ions such as Zn(II), Cu(II), Co(II), Ni(II), Cd(II) and Mn(II). The new compounds were characterized by standard physico-chemical procedures, and assayed as inhibitors of three CA isozymes, CA I, II and IV. Very good inhibition has been evidenced both for the parent sulfonamides as well as for the prepared complexes, against all three investigated isozymes. Some of these new complexes as well as the parent sulfonamide, strongly lowered intraocular pressure (IOP) in normotensive rabbits when administered as a 2% solution into the eye.

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