scholarly journals Active-Site Models for the Nickel–Iron Hydrogenases: Effects of Ligands on Reactivity and Catalytic Properties

2011 ◽  
Vol 50 (19) ◽  
pp. 9554-9563 ◽  
Author(s):  
Maria E. Carroll ◽  
Bryan E. Barton ◽  
Danielle L. Gray ◽  
Amanda E. Mack ◽  
Thomas B. Rauchfuss
Keyword(s):  
Active Site ◽  
Catalytic Properties ◽  
Nickel Iron

scholarly journals A comparative study of class-D β-lactamases

1993 ◽  
Vol 292 (2) ◽  
pp. 555-562 ◽  
Author(s):  
P Ledent ◽  
X Raquet ◽  
B Joris ◽  
J Van Beeumen ◽  
J M Frère
Keyword(s):  
Active Site ◽  
Gene Sequence ◽  
Catalytic Properties ◽  
Ion Exchange Chromatography ◽  
Exchange Chromatography ◽  
Beta Lactamase ◽  
Serine Residue ◽  
Beta Lactamases ◽  
Class D ◽  
Burst Kinetics

Three class-D beta-lactamases (OXA2, OXA1 and PSE2) were produced and purified to protein homogeneity. 6 beta-Iodopenicillanate inactivated the OXA2 enzyme without detectable turnover. Labelling of the same beta-lactamase with 6 beta-iodo[3H]penicillanate allowed the identification of Ser-70 as the active-site serine residue. In agreement with previous reports, the apparent M(r) of the OXA2 enzyme as determined by molecular-sieve filtration, was significantly higher than that deduced from the gene sequence, but this was not due to an equilibrium between a monomer and a dimer. The heterogeneity of the OXA2 beta-lactamase on ion-exchange chromatography contrasted with the similarity of the catalytic properties of the various forms. A first overview of the enzymic properties of the three ‘oxacillinases’ is presented. With the OXA2 enzyme, ‘burst’ kinetics, implying branched pathways, seemed to prevail with many substrates.

Synthesis, Characterization, and Reactions of Functionalized Nickel–Iron Dithiolates Related to the Active Site of [NiFe]-Hydrogenases

2018 ◽  
Vol 37 (6) ◽  
pp. 1050-1061 ◽  
Author(s):  
Li-Cheng Song ◽  
Xiu-Yun Gao ◽  
Wen-Bo Liu ◽  
Hong-Tao Zhang ◽  
Meng Cao
Keyword(s):  
Active Site ◽  
Nickel Iron

Dithiolato- and halogenido-bridged nickel–iron complexes related to the active site of [NiFe]-H2ases: preparation, structures, and electrocatalytic H2 production

2017 ◽  
Vol 46 (30) ◽  
pp. 10003-10013 ◽  
Author(s):  
Li-Cheng Song ◽  
Xiao-Feng Han ◽  
Wei Chen ◽  
Jia-Peng Li ◽  
Xu-Yong Wang
Keyword(s):  
Active Site ◽  
Iron Complexes ◽  
H2 Production ◽  
Nickel Iron

A new series of [NiFe]-H2ase mimics (5a,b–7a,b) has been prepared and structurally characterized; particularly, they have been found to be pre-catalysts for H2 production from Cl2CHCO2H under CV conditions.

Investigation of the Catalytic Properties of the Dysthrombin, Thrombin Quick

1979 ◽  
Author(s):  
R.A. Henriksen ◽  
W.G. Owen ◽  
M.E. Nesheim ◽  
K.G. Mann
Keyword(s):  
Active Site ◽  
Mayo Clinic ◽  
Active Sites ◽  
Fluorescence Enhancement ◽  
Catalytic Mechanism ◽  
Antithrombin Iii ◽  
Catalytic Properties ◽  
Inhibitor Binding ◽  
Equivalent Number ◽  
Aggregation Of Platelets

Thrombin Quick (TQ) may be isolated following treatment of Prothrombin Quick [Owen, et al, Mayo Clinic Proceedings, 53: 29-33, (1978)] with Taipan venom, phospholipid and Ca2+. The clotting activity of TQ with fibrinogen is 1/200 that of normal thrombin (T) The activation of Factors V and VIII, and the aggregation of platelets by TQ occurs with an effectiveness of about 1/50 that of thrombin. When incubated with antithrombin III, both T and TQ form inhibitor complexes as determined by dodecylsulfate gel electropheresis. Titration of T and TQ with the fluorescent inhibitor dansylarginine-4-ethylpiperidine amide indicates an equivalent number of active sites based on protein absorption at 280 nm. However, the two enzymes may be distinguished by the decreased fluorescence enhancement observed with TQ relative to T, indicating an increased polarity in the inhibitor binding site of TQ. With the substrate benzoylarginine ethylester, TQ has a Km = 4.5 x 10-5M and kcat - 6.93 compared to Km = 4.0 × 10-5M and kcat = 17.7 for T. This indicates that the defect in TQ esterase activity is in the catalytic mechanism itself and not in substrate binding. The rate of inhibition of TQ by diisopropylphosphofluoridate is decreased. Decreased acylation and deacylation rates for TQ relative to T are observed for tydrolysis of the active site titrant 4-methyumbel1 i feryl-p-guanidlnobenzoate.

Catalytic properties of key active site mutants of flavocytochrome P-450 BM3

1999 ◽  
Vol 27 (1) ◽  
pp. A44-A44 ◽  
Author(s):  
M.A. Noble ◽  
C.S. Miles ◽  
G.A. Reid ◽  
S.K. Chapman ◽  
A.W. Munro
Keyword(s):  
Active Site ◽  
Catalytic Properties ◽  
Active Site Mutants

Density Functional Calculations for Modeling the Oxidized States of the Active Site of Nickel−Iron Hydrogenases. 1. Verification of the Method with Paramagnetic Ni and Co Complexes

2002 ◽  
Vol 41 (17) ◽  
pp. 4417-4423 ◽  
Author(s):  
Christian Stadler ◽  
Antonio L. de Lacey ◽  
Belén Hernández ◽  
Víctor M. Fernández ◽  
Jose C. Conesa
Keyword(s):  
Active Site ◽  
Density Functional Calculations ◽  
Density Functional ◽  
Nickel Iron

Effect of E20D Substitution in the Active Site ofEscherichia coliInorganic Pyrophosphatase on Its Quaternary Structure and Catalytic Properties†

Biochemistry ◽  
1996 ◽  
Vol 35 (15) ◽  
pp. 4662-4669 ◽  
Author(s):  
Sergei E. Volk ◽  
Valerii Yu. Dudarenkov ◽  
Jarmo Käpylä ◽  
Vladimir N. Kasho ◽  
Olga A. Voloshina ◽  
...  
Keyword(s):  
Active Site ◽  
Quaternary Structure ◽  
Catalytic Properties
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