Spectroscopic studies on some sulphur-containing amino acid complexes of cobalt, nickel and copper

1974 ◽  
Vol 27 (8) ◽  
pp. 1629 ◽  
Author(s):  
RJ Magee ◽  
W Mazurek ◽  
MJ O'Conner ◽  
AT Phillip
Keyword(s):  
Amino Acids ◽  
Amino Acid ◽  
Structural Analysis ◽  
Energy Level ◽  
Spectroscopic Studies ◽  
Optically Active ◽  
Ligand Field ◽  
Spectral Measurements ◽  
X Ray ◽  
Cobalt Nickel

The synthesis of three potentially sexadentate optically active sulphur-containing amino acids, 2,9- diamino-4,7-dithiadecanedioic acid [(R,R)-ebc], 2,ll-diamino-5,8-dithiadodecanedioic acid [(S,S)- ebhc] and 2,7-di(3'-thiabuty1)-3,6-diazaoctanedioic acid [(S,S)-ebm] are described. Some metal complexes of the acids with cobalt, nickel and copper are characterized by spectroscopic measurements. The complex�� (-)589[Co{(S,S)-ebm}] ClO4 is formed stereospecifically and an X-ray structural analysis shows it to have the Δ-trans(O) configuration. The c.d. spectrum shows the presence of three bands due to the splitting of the T1g energy level by the effective C2 symmetry of the ligand field. Some polymeric cobalt(11) and nickel(11) complexes are also described. Spectral measurements indicate an octahedral coordination of the ligands involved. Several copper(11) complexes are also described.

Circular dichroism spectra of amino acid complexes. II. Chelated amino acid complexes with the CoN5O chromophore

1970 ◽  
Vol 23 (9) ◽  
pp. 1735 ◽  
Author(s):  
CJ Hawkins ◽  
PJ Lawson
Keyword(s):  
Amino Acids ◽  
Circular Dichroism ◽  
Amino Acid ◽  
Visible Region ◽  
Optically Active ◽  
Circular Dichroism Spectra ◽  
Amino Acid Complexes ◽  
Similar Series ◽  
Cotton Effects ◽  
Circular Dichroïsm

The circular dichroism spectra of a series of optically active (α-aminocarboxylato)tetraamminecobalt(111) complexes have been measured in aqueous solution, and in the presence of salts of polarizable anions. The observed spectra in the visible region have been analysed to determine the signs of the Cotton effects of the three components of the 1A1g ↔ 1T1g cobalt(111) transition. For L-amino acids, the transition with A2g(D4h) parentage is negative, and the two transitions with Eg(D4h) parentage have opposite signs. Published circular dichroism spectra of complexes of the type [Co(en)2(L-am)]2+ were similarly interpreted in terms of a perturbed tetragonal chromophore, and it was shown that the vicinal effect of the L-amino acids imposed the same signs onto the component transitions as for the tetraammines and for a similar series of pentaamminecobalt(111) complexes.

Sorption of α-amino-acids by copper montmorillonite

Clay Minerals ◽  
1967 ◽  
Vol 7 (2) ◽  
pp. 167-176 ◽  
Author(s):  
W. Bodenheimer ◽  
L. Heller
Keyword(s):  
Amino Acids ◽  
Amino Acid ◽  
Complex Formation ◽  
Glutamic Acid ◽  
Acid Complex ◽  
X Ray ◽  
Ray Methods

AbstractSorption of an acidic, amphoteric, sulphur containing and basic α-amino-acid (glutamic acid, glycine, methionine and lysine) by copper montmorillonite was studied by chemical and X-ray methods. With glutamic acid complex formation occurs only in solution but increasing basicity of the aminoacid favours complex formation in the clay interlayers.

X-ray studies on crystalline complexes involving amino acids and peptides. XL. Conformational variability, recurring and new features of aggregation, and effect of chirality in the malonic acid complexes of DL- and L-arginine

2002 ◽  
Vol 58 (6) ◽  
pp. 1051-1056 ◽  
Author(s):  
N. T. Saraswathi ◽  
M. Vijayan
Keyword(s):  
Amino Acids ◽  
Hydrogen Bonding ◽  
Amino Acid ◽  
Crystal Structures ◽  
Malonic Acid ◽  
Conformational Flexibility ◽  
X Ray ◽  
Conformational Variability ◽  
Aggregation Pattern ◽  
Positively Charged

The crystal structures of the complexes of malonic acid with DL- and L-arginine, which contain positively charged argininium ions and negatively charged semimalonate ions, further demonstrate the conformational flexibility of amino acids. A larger proportion of folded conformations than would be expected on the basis of steric consideration appears to occur in arginine, presumably because of the requirements of hydrogen bonding. The aggregation pattern in the DL-arginine complex bears varying degrees of resemblance to patterns observed in other similar structures. An antiparallel hydrogen-bonded dimeric arrangement of arginine, and to a lesser extent lysine, is a recurring motif. Similarities also exist among the structures in the interactions with this motif and its assembly into larger features of aggregation. However, the aggregation pattern observed in the L-arginine complex differs from any observed so far, which demonstrates that all the general patterns of amino-acid aggregation have not yet been elucidated. The two complexes represent cases where the reversal of the chirality of half the amino-acid molecules leads to a fundamentally different aggregation pattern.

Preparation and Properties of Oxo-Centered Trinuclear Chromium(III) Complexes with Bridging Optically Active Amino Acids, [Cr3(μ3-O)(μ-O,O′-amino-acid)6(H2O)3]7+

1991 ◽  
Vol 64 (11) ◽  
pp. 3463-3465 ◽  
Author(s):  
Hisashi Kato ◽  
Kou Nakata ◽  
Akira Nagasawa ◽  
Tadashi Yamaguchi ◽  
Yoichi Sasaki ◽  
...  
Keyword(s):  
Amino Acids ◽  
Amino Acid ◽  
Optically Active

scholarly journals The Uncommon Active Site of D-Amino Acid Transaminase from Haliscomenobacter hydrossis: Biochemical and Structural Insights into the New Enzyme

Molecules ◽  
2021 ◽  
Vol 26 (16) ◽  
pp. 5053
Author(s):  
Alina K. Bakunova ◽  
Alena Yu. Nikolaeva ◽  
Tatiana V. Rakitina ◽  
Tatiana Y. Isaikina ◽  
Maria G. Khrenova ◽  
...  
Keyword(s):  
Amino Acids ◽  
Amino Acid ◽  
Structural Analysis ◽  
Active Site ◽  
Active Sites ◽  
Structural Basis ◽  
Active Site Residues ◽  
Type Iv ◽  
Fold Type ◽  
Arginine Residues

Among industrially important pyridoxal-5’-phosphate (PLP)-dependent transaminases of fold type IV D-amino acid transaminases are the least studied. However, the development of cascade enzymatic processes, including the synthesis of D-amino acids, renewed interest in their study. Here, we describe the identification, biochemical and structural characterization of a new D-amino acid transaminase from Haliscomenobacter hydrossis (Halhy). The new enzyme is strictly specific towards D-amino acids and their keto analogs; it demonstrates one of the highest rates of transamination between D-glutamate and pyruvate. We obtained the crystal structure of the Halhy in the holo form with the protonated Schiff base formed by the K143 and the PLP. Structural analysis revealed a novel set of the active site residues that differ from the key residues forming the active sites of the previously studied D-amino acids transaminases. The active site of Halhy includes three arginine residues, one of which is unique among studied transaminases. We identified critical residues for the Halhy catalytic activity and suggested functions of the arginine residues based on the comparative structural analysis, mutagenesis, and molecular modeling simulations. We suggested a strong positive charge in the O-pocket and the unshaped P-pocket as a structural code for the D-amino acid specificity among transaminases of PLP fold type IV. Characteristics of Halhy complement our knowledge of the structural basis of substrate specificity of D-amino acid transaminases and the sequence-structure-function relationships in these enzymes.

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