Stringency of the 2-His–1-Asp Active-Site Motif in Prolyl 4-Hydroxylase

2011 ◽  
pp. 242-253
Author(s):  
Kelly Gorres ◽  
Khian Pua ◽  
Ronald Raines
Keyword(s):  
Active Site ◽  
Active Site Motif

scholarly journals Understanding the Role of Histidine in the GHSxG Acyltransferase Active Site Motif: Evidence for Histidine Stabilization of the Malonyl-Enzyme Intermediate

PLoS ONE ◽  
2014 ◽  
Vol 9 (10) ◽  
pp. e109421 ◽  
Author(s):  
Sean Poust ◽  
Isu Yoon ◽  
Paul D. Adams ◽  
Leonard Katz ◽  
Christopher J. Petzold ◽  
...  
Keyword(s):  
Active Site ◽  
Active Site Motif ◽  
Enzyme Intermediate

scholarly journals Glutathione-dependent activities of Trypanosoma cruzi p52 makes it a new member of the thiol:disulphide oxidoreductase family

1997 ◽  
Vol 322 (1) ◽  
pp. 43-48 ◽  
Author(s):  
Mireille MOUTIEZ ◽  
Eric QUÉMÉNEUR ◽  
Christian SERGHERAERT ◽  
Valérie LUCAS ◽  
André TARTAR ◽  
...  
Keyword(s):  
Trypanosoma Cruzi ◽  
Active Site ◽  
Catalytic Mechanism ◽  
Reductase Activity ◽  
Redox Balance ◽  
Ribonuclease A ◽  
Physiological Conditions ◽  
Active Site Motif ◽  
Key Enzyme ◽  
Low Rate

Trypanothione:glutathione disulphide thioltransferase of Trypanosoma cruzi (p52) is a key enzyme in the regulation of the intracellular thiolŐdisulphide redox balance by reducing glutathione disulphide. Here we show that p52, like other disulphide oxidoreductases possessing the CXXC active site motif, catalyses the reduction of low-molecular-mass disulphides (hydroxyethyldisulphide) as well as protein disulphides (insulin). However, p52 seems to be a poor oxidase under physiological conditions as evidenced by its very low rate for oxidative renaturation of reduced ribonuclease A. Like thioltransferase and protein disulphide isomerase, p52 was found to possess a glutathione-dependent dehydroascorbate reductase activity. The kinetic parameters were in the same range as those determined for mammalian dehydroascorbate reductases. A catalytic mechanism taking into account both trypanothione- and glutathione-dependent reduction reactions was proposed. This newly characterized enzyme is specific for the parasite and provides a new target for specific chemotherapy.

scholarly journals Kinetic and Structural Characterization of the First B3 Metallo-β-Lactamase with an Active Site Glutamic Acid

2021 ◽  
Author(s):  
Liam A. Wilson ◽  
Esmée G. Knaven ◽  
Marc T. Morris ◽  
Marcelo Monteiro Pedroso ◽  
Christopher J. Schofield ◽  
...  
Keyword(s):  
Glutamic Acid ◽  
Structural Characterization ◽  
Active Site ◽  
Structural Diversity ◽  
Kinetic Properties ◽  
Design Studies ◽  
Degrading Bacterium ◽  
Active Site Motif ◽  
Wide Range

The structural diversity in metallo-β-lactamases (MBLs), especially in the vicinity of the active site, has been a major hurdle in the development of clinically effective inhibitors. Representatives from three variants of the B3 MBL subclass, containing either the canonical HHH/DHH active site motif (present in the majority of MBLs in this subclass) or the QHH/DHH (B3-Q) or HRH/DQK (B3-RQK) variations were reported previously. Here, we describe the structure and kinetic properties of the first example (SIE-1) of a fourth variant containing the EHH/DHH active site motif (B3-E). SIE-1 was identified in the hexachlorocyclohexane-degrading bacterium Sphingobium indicum , and kinetic analyses demonstrate that although it is active against a wide range of antibiotics its efficiency is lower than that of other B3 MBLs, but with improved efficiency towards cephalosporins relative to other β-lactam substrates. The overall fold of SIE-1 is characteristic of the MBLs; the notable variation is observed in the Zn1 site due to the replacement of the canonical His116 by a glutamate. The unusual preference of SIE-1 for cephalosporins and its occurrence in a widespread environmental organism suggests scope for increased MBL-mediated β-lactam resistance. It is thus relevant to include SIE-1 into MBL inhibitor design studies to widen the therapeutic scope of much needed anti-resistance drugs.

Permutation of the Active Site Motif of Tryparedoxin 2

2000 ◽  
Vol 381 (3) ◽  
pp. 211-219 ◽  
Author(s):  
Peter Steinert ◽  
Karin Plank-Schumacher ◽  
Marisa Montemartini ◽  
Hans-Jürgen Hecht ◽  
Leopold Flohé
Keyword(s):  
Active Site ◽  
Active Sites ◽  
Antioxidant Defense ◽  
Positive Charge ◽  
Specific Activity ◽  
Molecular Targets ◽  
E Coli ◽  
Active Site Motif ◽  
Nickel Chelate ◽  
Sitedirected Mutagenesis

Abstract Tryparedoxins (TXN) are thioredoxinrelated proteins which, as trypanothione:peroxiredoxin oxidoreductases, constitute the trypanothionedependent antioxidant defense and may also serve as substrates for ribonucleotide reductase in trypanosomatids. The active site motif of TXN2, [40]WCPPCR[45], of Crithidia fasciculata was mutated by sitedirected mutagenesis and eight corresponding muteins were expressed in E. coli as terminally Histagged proteins, purified to homogeneity by nickel chelate chromatography, and characterized in terms of specific activity, specificity and, if possible, kinetics. Exchange of Cys41 and Cys44 by serine yielded inactive products confirming their presumed involvement in catalysis. Exchange of Arg45 by aspartate resulted in loss of activity, suggesting an activation of active site cysteines by the positive charge of Arg45. Substitution of Trp40 by phenylalanine or tyrosine resulted in moderate decrease of specific activity, as did exchange of Pro42 by glycine. Kinetic analysis of these three muteins revealed that primarily the reaction with trypanothione is affected by the mutations. Simulation of thioredoxin or glutaredoxin like active sites in TXN2 (P42G and W40T/P43Y, respectively) did not result in thioredoxin or glutaredoxin like activities. These data underscore that TXNs, although belonging to the thioredoxin superfamily, represent a group of enzymes distinct from thioredoxins and glutaredoxins in terms of specificity, and appear attractive as molecular targets for the design of trypanocidal compounds.

scholarly journals The Conserved Active Site Motif A ofEscherichia coliDNA Polymerase I Is Highly Mutable

2001 ◽  
Vol 276 (22) ◽  
pp. 18836-18842 ◽  
Author(s):  
Akeo Shinkai ◽  
Premal H. Patel ◽  
Lawrence A. Loeb
Keyword(s):  
Active Site ◽  
Active Site Motif ◽  
Polymerase I

Structure of PEP carboxykinase from the succinate-producingActinobacillus succinogenes: a new conserved active-site motif

2005 ◽  
Vol 61 (7) ◽  
pp. 903-912 ◽  
Author(s):  
Yvonne A. Leduc ◽  
Lata Prasad ◽  
Maris Laivenieks ◽  
J. Gregory Zeikus ◽  
Louis T. J. Delbaere
Keyword(s):  
Active Site ◽  
Active Site Motif ◽  
Pep Carboxykinase

scholarly journals An Extended Active-site Motif Controls the Reactivity of the Thioredoxin Fold

2014 ◽  
Vol 289 (12) ◽  
pp. 8681-8696 ◽  
Author(s):  
Despoina A. I. Mavridou ◽  
Emmanuel Saridakis ◽  
Paraskevi Kritsiligkou ◽  
Erin C. Mozley ◽  
Stuart J. Ferguson ◽  
...  
Keyword(s):  
Active Site ◽  
Active Site Motif
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