The effect of nickel(II) and cobalt(III) and other metal ions on the racemization of free and bound L-alanine

Smith, Grant Gill; Khatib, Awni; Reddy, G. S.

doi:10.1021/ja00340a026

Cited by 36 publications

(19 citation statements)

References 3 publications

(2 reference statements)

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“…Ionic mechanisms of racemization and epimerizationwere proposed by G. G. Smithand co-workers 6,[12][13][14][15][16][17][18][19][20] , whoshowed that the rates of racemization of peptides were faster than those of free amino acids. However, this research wasmainly restricted to the epimerization of linear peptides and the racemization of 2,5-diketopiperazines bearing one chiral center, and did not consider cyclic diastereomeric peptides.…”

Section: Oriental Journal Of Chemistrymentioning

confidence: 99%

Epimerization of Cyclic Alanyl-Alanine in Basic Solutions

Munegumia¹,

Fujimoto²,

MichioTakada³

et al. 2014

Orient. J. Chem

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Alanine anhydrides (Cyclo-(Ala-Ala)) are the simplest dipeptides that have two chiral centers and three diastereomers: Cyclo-(L-Ala-L-Ala), Cyclo-(D-Ala-D-Ala), and Cyclo-(L-Ala-D-Ala).Analysis of the epimerization of these peptides may throw light on the development of homochirality in proteins. We show that the epimerization rate of Cyclo-(L-Ala-L-Ala) and Cyclo-(D-Ala-D-Ala) is higher than that of Cyclo-(L-Ala-D-Ala), while the ring-opening rates of Cyclo-(L-Ala-L-Ala) and Cyclo-(D-Ala-DAla) arelower than that of Cyclo-(L-Ala-D-Ala) in basic aqueous solutions. The total reaction resulted in the preferred stability of Cyclo-(L-Ala-L-Ala) and Cyclo-(D-Ala-D-Ala) to Cyclo-(D-Ala-L-Ala).

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Section: Oriental Journal Of Chemistrymentioning

confidence: 99%

Epimerization of Cyclic Alanyl-Alanine in Basic Solutions

Munegumia¹,

Fujimoto²,

MichioTakada³

et al. 2014

Orient. J. Chem

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“…Ni (1)-O(3) 2.0422 (17) Ni (1)-O(1) 2.0567 (17) Ni (1) (1) 115.63 (13) are occupied by water molecules, and the equatorial plane is occupied by the chelating alanine ligands. Distortions about nickel atom are observed, in which slightly different bond distances to the coordinating water molecules; essentially identical bond distances to the nitrogens and slightly different bond distances to the chelating oxygens O1 and O3.…”

Section: Bond Distancementioning

confidence: 99%

“…Metals bound to amino acids are essential for the catalytic function of certain enzymes, and their chemistry has received a great deal of research interest due to their significant interaction with enzymes and with different organic ligands which enables a better understanding of the antitumor/viral activities of this class of compounds and for modeling substrates involved in enzyme inhibition [6,7]. A number of complexes of amino acids with many transition metal ions have been prepared and thoroughly studied [8][9][10][11][12][13][14]. A complex of alanine with nickel(II) was reported [15] and described as a neutral bis(alaninato)diaqua nickel(II), and its X-ray crystal structure seems not to have been explicitly studied.…”

Section: Introductionmentioning

confidence: 99%

Crystal Structure of [Bis(L-Alaninato)Diaqua]Nickel(II) Dihydrate

Khatib

Aqra

Deamer

et al. 2009

Research Letters in Inorganic Chemistry

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The title complex, [Ni(C 3 H 6 O 2 N) 2 (H 2 O) 2 ]·2H 2 O, has been prepared from nickel(II) chloride in aqueous solution by adding L-alanine and potassium hydroxide. It has been crystallized from aqueous solution, and its structure was determined by X-ray structure analysis. The nickel(II) ion adopts distorted octahedral coordination geometry with two bidentate L-alanine molecules and two water molecules. The complex is neutral and dihydrated. The crystal structure shows the hydrogen bonding between water and amide hydrogens within the lattice, and each fragment of the complex contains two water molecules as hydrated water. The L-alaninato ligand skeleton of the compound adopts the most stable trans-III configuration in the solid state. The alternating two five-membered chelate rings are in the stable gauche conformation.

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“…[6][7][8][9][10] When the enantioselective resolution of a racemate is combined with the concomitant racemization of the non, or only partially, transformed enantiomer, the results are ideally a 100% chemical yield and enantiomeric excess, namely a dynamic kinetic resolution (DKR). [11][12][13][14][15] For an effective DKR, several requirements have to be met. The resolution must be highly selective (E P 20-100), the process irreversible and the final product should be stable toward racemization.…”

Section: Introductionmentioning

confidence: 99%