Binding of Oxovanadium(IV) to Dipeptides Containing Histidine and Cysteine Residues

Abstract

The complexation of the oxovanadium(IV) ion with five dipeptides containing L-histidine or L-cysteine (GlyHis, HisHis, HisGly, CysGly, GlyCys) was studied. L-histidinamide (HisNH 2 ) was assumed as a model system for dipeptides with L-histidine in the N-terminal position. The study was performed in aqueous solution through the combined application of potentiometric and spectroscopic (electronic absorption and EPR) techniques. The results indicate that simple dipeptides lacking a strong anchoring group can form monoand bischelated complexes with the V IV O ion if a suitable "donor" is present in the chain. The ligands behave like amino acids in the acidic and neutral pH range, inhibit the precipitation of hydroxides and suppress the formation of hy-

Potentiometric, Spectroscopic and DFT Study of the VIVO Complexes Formed by Di(pyridin‐2‐yl) Ligands

“…[15] The value of A z predicted by the "additivity rule" is 159 ϫ 10 O ion is -1 (VOLH -1 ) and -2 (VOLH -2 ), respectively. [13] The two expected values are significantly higher than those measured: as discussed later, it is possible to predict the A z value for the two species also by DFT methods, which give results comparable with those experimentally measured. However, by following what was done by Saladino and Larsen [31] for V IV O imidazole species after the fundamental work of Pecoraro and co-workers, [32] we studied through DFT calculations the value of 51 V A z in V…”

“…[11] Recently the role of the anchoring groups was studied with V IV O and it was found that phenolate O -, alcoholate O -, thiolate S -, carboxylate COO -, amino NH 2 , and imidazole N are effective in promoting peptide amide deprotonation and coordination. [12,13] Many examples of V IV O complexes containing a V-N -(amide) bond, both in solution and in the solid state, were characterized over the last years in the literature. [12][13][14] We recently demonstrated that the di(imidazol-2-yl) residue behaves as a good anchoring group, avoiding the hydrolysis and precipitation of vanadium hydroxide and allowing for the coordination of the amide nitrogen-N -.…”

“…[12,13] Many examples of V IV O complexes containing a V-N -(amide) bond, both in solution and in the solid state, were characterized over the last years in the literature. [12][13][14] We recently demonstrated that the di(imidazol-2-yl) residue behaves as a good anchoring group, avoiding the hydrolysis and precipitation of vanadium hydroxide and allowing for the coordination of the amide nitrogen-N -. [15] Pyridine nitrogen is known as a good donor group in vanadium coordination chemistry, [16] and therefore di(pyridin-2-yl) derivatives of amino acids could be good candidates to complex the V IV O ion and promote the coordination of an amide bond.…”

Preface: Recent Advances and Highlights of the 5th International Vanadium Symposium

“…catalysis, insulin-enhancing, anti-tumor) of already known compounds. For example: Schiff bases of the salen-type (66), reduced Schiff bases of salan-type (171,172,173), sal-amino acidate and other Schiff bases, including the reducedtype derivatives, (28,78,193,195,197,216,217), amino acids or peptides (186)(187)(188)(189)196), hydroxycarboxylates (198,218,219,221) 158,180,184,[224][225][226][227][228][229][230][231][232][233][234].…”

“…19,66,[171][172][173][174][175][176], pyrone, pyridinone and pyrimidinone complexes (177)(178)(179), several types of Schiff bases and related complexes (66, [180][181][182], picolinato (e.g. 183), quinoline derivatives (184) dipicolinato complexes (185), compounds involving ligands such as amino acids or derivatives (28,(186)(187)(188)(189)(190)(191)(192)(193)(194)(195)(196)(197), hydroxycarboxylates (198,199), but novel classes of coordination compounds and other new reports on previously known compounds are too many to name.…”