Brief History of Glyoxalase I and What We Have Learned about Metal Ion-Dependent, Enzyme-Catalyzed Isomerizations

2001 ◽  
Vol 387 (1) ◽  
pp. 1-10 ◽  
Author(s):  
Donald J. Creighton ◽  
Diana S. Hamilton
Keyword(s):  
Metal Ion ◽  
Glyoxalase I ◽  
History Of

Freeze-etch TEM of aqueous polymer gel network morphology

1986 ◽  
Vol 44 ◽  
pp. 796-797
Author(s):  
J. A. N. Zasadzinski ◽  
R. K. Prud'homme
Keyword(s):  
Metal Ion ◽  
Polymer Network ◽  
Polymer Gels ◽  
Polymer Gel ◽  
Deformation History ◽  
Crosslinked Polymer ◽  
Aqueous Polymer ◽  
History Of ◽  
Gel Network ◽  
Network Morphology

The rheological and mechanical properties of crosslinked polymer gels arise from the structure of the gel network. In turn, the structure of the gel network results from: thermodynamically determined interactions between the polymer chain segments, the interactions of the crosslinking metal ion with the polymer, and the deformation history of the network. Interpretations of mechanical and rheological measurements on polymer gels invariably begin with a conceptual model of,the microstructure of the gel network derived from polymer kinetic theory. In the present work, we use freeze-etch replication TEM to image the polymer network morphology of titanium crosslinked hydroxypropyl guars in an attempt to directly relate macroscopic phenomena with network structure.

scholarly journals Metabolomic Characterization of a Low Phytic Acid and High Anti-oxidative Cultivar of Turmeric

2015 ◽  
Vol 10 (2) ◽  
pp. 1934578X1501000
Author(s):  
Ken Tanaka ◽  
Masanori Arita ◽  
Donghan Li ◽  
Naoaki Ono ◽  
Yasuhiro Tezuka ◽  
...  
Keyword(s):  
Phytic Acid ◽  
Metal Ion ◽  
Curcuma Longa ◽  
Food Additives ◽  
Chemical Properties ◽  
Lower Amount ◽  
Low Phytic Acid ◽  
History Of ◽  
History Of Use

Turmeric, the rhizome of Curcuma longa, has a long history of use as a spice and also as a traditional medicine in many Asian countries. To reveal unique morphological features of a newly registered Curcuma cultivar, C longa cv. Okinawa Ougon (Ougon), non-targeted LC-MS and GC-MS analyses were conducted. The analysis revealed its distinctive chemical properties: lower amount of phytic acid and inorganic metals such as Fe, Mn, and Al, as well as higher concentrations of reduced derivatives of curcuminoids, such as dihydrobisdemethoxycurcumin, tetrahydrobisdemethoxycurcumin, dihydrodemethoxycurcumin, and tetrahydrodemethoxycurcumin. In addition, germacrane-type sesquiterpenes were almost absent although α-humulene and β-caryophyllene, generated by the same biosynthetic route, were present. Presumably the alternation of the metal ion content, serving as a cofactor of sesquiterpene synthase, modulates the resulting variation of the sesquiterpenes. In summary, the cultivar Ougon is considered a promising candidate for functional food additives.

Glyoxalase I – structure, function and a critical role in the enzymatic defence against glycation

2003 ◽  
Vol 31 (6) ◽  
pp. 1343-1348 ◽  
Author(s):  
P.J. Thornalley
Keyword(s):  
Metal Ion ◽  
Catalytic Mechanism ◽  
Critical Role ◽  
Glyoxalase I ◽  
Water Molecules ◽  
Glyoxalase System ◽  
E Coli ◽  
Antimalarial Agents

Glyoxalase I is part of the glyoxalase system present in the cytosol of cells. The glyoxalase system catalyses the conversion of reactive, acyclic α-oxoaldehydes into the corresponding α-hydroxyacids. Glyoxalase I catalyses the isomerization of the hemithioacetal, formed spontaneously from α-oxoaldehyde and GSH, to S-2-hydroxyacylglutathione derivatives [RCOCH(OH)-SG→RCH(OH)CO-SG], and in so doing decreases the steady-state concentrations of physiological α-oxoaldehydes and associated glycation reactions. Physiological substrates of glyoxalase I are methylglyoxal, glyoxal and other acyclic α-oxoaldehydes. Human glyoxalase I is a dimeric Zn2+ metalloenzyme of molecular mass 42 kDa. Glyoxalase I from Escherichia coli is a Ni2+ metalloenzyme. The crystal structures of human and E. coli glyoxalase I have been determined to 1.7 and 1.5 Å resolution. The Zn2+ site comprises two structurally equivalent residues from each domain – Gln-33A, Glu-99A, His-126B, Glu-172B and two water molecules. The Ni2+ binding site comprises His-5A, Glu-56A, His-74B, Glu-122B and two water molecules. The catalytic reaction involves base-catalysed shielded-proton transfer from C-1 to C-2 of the hemithioacetal to form an ene-diol intermediate and rapid ketonization to the thioester product. R- and S-enantiomers of the hemithioacetal are bound in the active site, displacing the water molecules in the metal ion primary co-ordination shell. It has been proposed that Glu-172 is the catalytic base for the S-substrate enantiomer and Glu-99 the catalytic base for the R-substrate enantiomer; Glu-172 then reprotonates the ene-diol stereospecifically to form the R-2-hydroxyacylglutathione product. By analogy with the human enzyme, Glu-56 and Glu-122 may be the bases involved in the catalytic mechanism of E. coli glyoxalase I. The suppression of α-oxoaldehyde-mediated glycation by glyoxalase I is particularly important in diabetes and uraemia, where α-oxoaldehyde concentrations are increased. Decreased glyoxalase I activity in situ due to the aging process and oxidative stress results in increased glycation and tissue damage. Inhibition of glyoxalase I pharmacologically with specific inhibitors leads to the accumulation of α-oxoaldehydes to cytotoxic levels; cell-permeable glyoxalase I inhibitors are antitumour and antimalarial agents. Glyoxalase I has a critical role in the prevention of glycation reactions mediated by methylglyoxal, glyoxal and other α-oxoaldehydes in vivo.

scholarly journals A universal graphitic interlayered centroid intercalation theory for intercalation chemistry

2021 ◽  
Author(s):  
Kemeng Ji ◽  
Kailong Hu ◽  
Yuhao Shen ◽  
Yoshikazu Ito ◽  
Cheng Liu ◽  
...  
Keyword(s):  
Metal Ion ◽  
Nitrogen Doping ◽  
Model Case ◽  
Storage Mechanism ◽  
Intercalation Reaction ◽  
Crystal Texture ◽  
Carbon Foams ◽  
History Of ◽  
Electrochemical Storage ◽  
New Research

Abstract Neither of the two widely used staging models in the long history of intercalation chemistry, namely the classical Rüdorff-Hofmann model proposed in 1938 and the pleated-layer domain-modified one in 1969, can explain the intercalation reaction phenomena and mechanism logically. Taking the landmark potassium-intercalation reaction of graphite as a model case and two advanced monolithic graphitic/graphenic carbon foams as model electrodes, here we have revealed that the electrochemical storage of potassium in graphitic/graphenic carbon (as that of lithium) obeys a simple interlayered centroid intercalation (ICIC) rule to achieve the staged potassium intercalation into each graphitic interlayer: C → KC72 → KC24 → KC8. Moreover, judging from the typical potassium-storage behaviors and crystal texture of graphitic electrodes, nitrogen doping and pre-embedded K atoms would enable incoming K+ ions to perform fast pseudocapacitive diffusion in graphitic gallery. This study not only makes clear the basic K-storage mechanism and phenomena in graphitic carbon, but also establishes a more reasonable ICIC model for intercalation chemistry, and thus may help open a new research era for this field as well as graphite-based metal-ion batteries.

scholarly journals Episodes of horizontal gene-transfer and gene-fusion led to co-existence of different metal-ion specific glyoxalase I

2013 ◽  
Vol 3 (1) ◽  
Author(s):  
Charanpreet Kaur ◽  
Anchal Vishnoi ◽  
Thilini Udayangani Ariyadasa ◽  
Alok Bhattacharya ◽  
Sneh Lata Singla-Pareek ◽  
...  
Keyword(s):  
Gene Transfer ◽  
Horizontal Gene Transfer ◽  
Metal Ion ◽  
Gene Fusion ◽  
Glyoxalase I

scholarly journals A Brief History of Photoactive Interlocked Systems Assembled by Transition Metal Template Synthesis

Photochem ◽  
2021 ◽  
Vol 1 (3) ◽  
pp. 411-433
Author(s):  
Vitor H. Rigolin ◽  
Liniquer A. Fontana ◽  
Jackson D. Megiatto
Keyword(s):  
Electron Transfer ◽  
Transition Metal ◽  
Electron Donor ◽  
Metal Ion ◽  
Energy And Electron Transfer ◽  
Donor Acceptor ◽  
History Of ◽  
Artificial Photosynthetic ◽  
Covalently Linked ◽  
Electron Transfer Processes

More than three decades of research efforts have yielded powerful methodologies based on transition metal template-directed syntheses for the assembly of a huge number of interlocked systems, molecular knots, machines and synthesizers. Such template techniques have been applied in the preparation of mechanically linked electron donor–acceptor artificial photosynthetic models. Consequently, synthetic challenging photoactive rotaxanes and catenanes have been reported, in which the chromophores are not covalently linked but are still associated with undergoing sequential energy (EnT) and electron transfer (ET) processes upon photoexcitation. Many interlocked photosynthetic models produce highly energetic, but still long-living charge separated states (CSS). The present work describes in a historical perspective some key advances in the field of photoactive interlocked systems assembled by transition metal template techniques, which illustrate the usefulness of rotaxanes and catenanes as molecular scaffolds to organize electron donor–acceptor groups. The effects of molecular dynamics, molecular topology, as well as the role of the transition metal ion used as template species, on the thermodynamic and kinetic parameters of the photoinduced energy and electron transfer processes in the interlocked systems are also discussed.

Comparative kinetics of Mg2+,Mn2+,Co2+, and Ni2+-activated glyoxalase I. Evaluation of the role of the metal ion

Biochemistry ◽  
1977 ◽  
Vol 16 (25) ◽  
pp. 5478-5484 ◽  
Author(s):  
Liang-Po B. Han ◽  
Christina M. Schimandle ◽  
Linda M. Davison ◽  
David L. Vander Jagt
Keyword(s):  
Metal Ion ◽  
Glyoxalase I ◽  
Kinetics Of

Bacterial glyoxalase I enzymes: structural and biochemical investigations

2014 ◽  
Vol 42 (2) ◽  
pp. 479-484 ◽  
Author(s):  
John F. Honek
Keyword(s):  
Metal Ion ◽  
Molecular Structures ◽  
Glyoxalase I ◽  
Structure Activity Relationships ◽  
Structure Activity

A number of bacterial glyoxalase I enzymes are maximally activated by Ni2+ and Co2+ ions, but are inactive in the presence of Zn2+, yet these enzymes will also bind this metal ion. The structure–activity relationships between these two classes of glyoxalase I serve as important clues as to how the molecular structures of these proteins control metal-activation profiles.

scholarly journals Investigation of metal binding and activation of Escherichia coli glyoxalase I: kinetic, thermodynamic and mutagenesis studies

2004 ◽  
Vol 377 (2) ◽  
pp. 309-316 ◽  
Author(s):  
Susan L. CLUGSTON ◽  
Rieko YAJIMA ◽  
John F. HONEK
Keyword(s):  
Escherichia Coli ◽  
Isothermal Titration Calorimetry ◽  
Metal Binding ◽  
Inductively Coupled Plasma ◽  
Metal Ion ◽  
Titration Calorimetry ◽  
Glyoxalase I ◽  
E Coli ◽  
Catalytic Metal ◽  
Bivalent Metals

GlxI (glyoxalase I) isomerizes the hemithioacetal formed between glutathione and methylglyoxal. Unlike other GlxI enzymes, Escherichia coli GlxI exhibits no activity with Zn2+ but maximal activation with Ni2+. To elucidate further the metal site in E. coli GlxI, several approaches were undertaken. Kinetic studies indicate that the catalytic metal ion affects the kcat without significantly affecting the Km for the substrate. Inductively coupled plasma analysis and isothermal titration calorimetry confirmed one metal ion bound to the enzyme, including Zn2+, which produces an inactive enzyme. Isothermal titration calorimetry was utilized to determine the relative binding affinity of GlxI for various bivalent metals. Each metal ion examined bound very tightly to GlxI with an association constant (Ka)>107 M−1, with the exception of Mn2+ (Ka of the order of 106 M−1). One of the ligands to the catalytic metal, His5, was altered to glutamine, a side chain found in the Zn2+-active Homo sapiens GlxI. The affinity of the mutant protein for all bivalent metals was drastically decreased. However, low levels of activity were now observed for Zn2+-bound GlxI. Although this residue has a marked effect on metal binding and activation, it is not the sole factor determining the differential metal activation between the human and E. coli GlxI enzymes.

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