Complexation copper -amino acid

Pagliarin, R., G. Sello, and M. Sisti. 1994. Model Studies for Predicting the Diastereoselectivity in the Condensation of Aldehydes with Zinc and Copper Complexes of Amino Acid Derivatives. Part 1. Analysis and realisation of the models. J. Mol. Struct. (Theochem) 312, 251-259. 

Copper(II) complexes of amino acids have been explored as chiral Lewis acid catalysts in the Diels-Alder reaction of 3-phenyl-l-(2-pyridyl)-2-propen-l-one with cyclopentadiene. The best results were obtained using /V-methyl-/.-tryptophan, but more interestingly, the highest ee values for the major endo adduct were achieved in aqueous solution273. 

A chiral amino-acid/copper complex is bound to a silica- or polymeric stationary phase and copper ions are included in the mobile phase to ensure there is no loss of copper. Amino acids then may be separated by the formation of diastereomeric copper complexes. Water stabilizes the complex by coordinating in an axial position. Steric factors then determine which of the two complexes is more stable. One of the water molecules is usually sterically hindered from coordinating with the copper. i ... 

The complexes of amino acids with copper are formed according to the general reaction shown in Equation 7.14 [47]. The formation constants for the copper-amino acid complexes are generally greater than that for copper ammonia complex [48]. Therefore, it is anticipated that amino acids should be more effective than ammonia in assisting the dissolution of oxidized copper during CMP. 

Arylations. Heterocycles typified by a-pyridone are N-arylated using Cul, KjCOj, in refluxing DMF. a-Amino acids are similarly derived jt-coordination of the copper-amino acid complexes is thought to facilitate the substitution. ... 

Kober, P. A., and K. Sugiura The Copper Complexes of Amino Acids,... 

Correia dos Santos, M. M., and M. L. S. Simoes Goncalves (1986), Electroanalytical Chemistry of Copper, Lead, and Zinc Complexes of Amino Acids at the Ionic Strength of Seawater (0.70 M NaClOJ, J. Electroanal. Chem. 208, 137-152. 

As is also shown in Figure 6.1, an interleukin-1-mediated [29] acute-phase response to many diseases involves a release of copper-thioneine-stored copper from the liver as ceruloplasmin, copper amino-acid complexes, and a copper albumin complex to meet increased metabolic needs for copper, which exceed normal needs, and plasma copper concentrations increase 200-300% above normal, as illustrated in Figure 6.3. The appropriate increase coupled... 

As shown in Table 6.6, copper complexes of amino acids were also effective analgesics, while their ligands were ineffective in the acetic acid-induced pain... 

Copper complexes of amino acids have also been found to be effective in preventing and reducing the severity of Shay ulcers [267, 268]. As data in Table 6.17 show, the copper complex of glycine was the most effective of all of the amino-acid complexes studied and it was essentially as effective as Propantheline in reducing ulcer number as well as ulcer severity [267]. 

In 1965, Denny et al. for the first time reported a catalytic asymmetric Kharasch-Sosnovsky reaction by using Cu(II)-(a)-ethyl camphorate as a catalyst, though enantioselectivity was low (Scheme 9) [21]. A quarter of a century later, natural or synthetic amino acids were introduced as chiral auxiliaries and much improved enantioselectivity (up to 65% ee) was achieved (Scheme 10) [22]. Although no detailed information on the structures of these copper complexes has been obtained, the observed non-linear relationship between the ee of the chiral auxiliary and the ee of the product suggests that the copper-amino acid complex is not monomeric but instead is oligomeric (at least dimeric) species [22e]. 

Hemocyanin possesses a catalase-like action (10, 12), albeit a weak one, in that it decomposes hydrogen peroxide into water and oxygen just as the hemeprotein catalase. The catalase-like action of hemocyanin is due to the protein-bound copper since neither copper-free hemocyanin nor free copper ions exhibit activity under equivalent conditions. Copper-amino acid complexes have been tested for catalase-like action, and it was reported that only the copper-arginine complex possesses catalase-like activity (13). However, we have found (37) as have other investigators (29, 40), that other amino acid complexes of copper also decompose H202. 

In surface waters the dissolved forms of copper are mostly complex compounds. Organic complexes with amino acids and humic substances, and the [CuG03(aq)]° carbonate complex prevail. Only a small fraction consists of the simple ionic form [8]. 

Incubation of pro-CAO with copper(II) salts in air initially yields two species, which show absorptions at 350 nm and 380 nm that have been assigned to Tyr —> Cu charge-transfer transitions. The 380 nm band appears to be irrelevant to cofactor synthesis,and probably arises from copper(ll) ions complexed to amino acids outside the active site. The 350 nm species is not obtained if pro-CAO is treated anaerobically with copper, although O2 is not consumed during its aerobic formation. Since there is no evidence for a Cu—O2 bond in this species, this may imply the existence of a separate 02-binding site remote from the copper ion, which would induce a protein conformational change in the presence of O2 to allow the 350 nm complex to form. 

The chemical properties of the polypeptides depend greatly on their complexity. Like amino acids, all the ordinary polypeptides, when their solutions are boiled with precipitated copper oxide, give blue, sometimes blue-violet solutions, and in this way differ from the diketo-piperazines, whose solutions remain colourless, t.e., they do not give copper salts. Leucyl-proline forms again an exception. 

Maurya MR, Kumar M, Pessoa JC (2008) Oxidation of p-chlorotoluene and cyclohexene catalyzed by polymer-anchored oxovanadium(IV) and copper(II) complexes of amino acid derived tridentate ligands. Dalton Trans 4220 232... 

The availability of copper in the body is somewhat different from that of iron. Copper in the Mood serum is bound in caeruloplasmin, Excessive dietary copper is predominately carried by serum albumin. Serum albumin copper is in the equilibrium with low molecular mass complexes of amino acids or small peptides. Unfortunately, the concentration of such complexes is below the detection limit. Regardless of the... 

Yasui et al. (1965 Yasui, 1965) studied the CD spectra of copper-amino acid complexes in more detail and showed that copper complexes with l-amino acids in water exhibit four Cotton effects in the region of the d-d absorption band positive at 830 and 730 nm and negative at 635 and 565 nm. The CD curves of the complexes of proline, hydroxyproline, and histidine are considerably different from those of other amino acid complexes for which the main CD band at ca. 630 nm shows the opposite positive Cotton effect. It was suggested that the vicinal effect of the asymmetric a-carbon atom is stronger than that of the asymmetric j -carbon atom (L-threonine and L-allothreonine) and thus determines the sign of the Cotton effects. 

Table 8.11 Energy values and molecular interaction energies for complexes of amino acids with the binuclear copper(II) derivative of iV-salicylidene-(i )-2-amino-l,l-ZJZs(2-butoxy-5-tc/t-butylphenyl)-3-phenyl-l-propanol.

Figure 2. Suggested non-covalent interaction in copper(II) bis complexes of amino acids...

TABLE VI. Spin Hamiltonian Parameters for Copper(IT) Ternary Complexes with Amino Acids in Water/Methanol 90 10 Solution at 150K... 

Often chromatographers have asked the TLC plate manufacturers if they could make chiral TLC layers. This would allow them to determine which of the five classes of chiral columns would be most useful for their enantiomer separations. Unfortunately, such layers would be very costly since a TLC plate is used only once. Only one plate is available, typically with a chir in its name. It is composed of a layer that is impregnated with proline and copper(II) ion to allow complexation of amino acids and amino alcohols for enantiomer separation. Unfortunately, this... 

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