X-ray absorption spectroscopic evidence for binding of the competitive inhibitor 2-mercaptoethanol to the nickel sites of Jack bean urease. A new nickel-nickel interaction in the inhibited enzyme

1990 ◽  
Vol 29 (4) ◽  
pp. 579-581 ◽  
Author(s):  
Patrick A. Clark ◽  
Dean E. Wilcox ◽  
Robert A. Scott
Keyword(s):  
Competitive Inhibitor ◽  
Jack Bean Urease ◽  
Jack Bean ◽  
Spectroscopic Evidence ◽  
X Ray ◽  
X Ray Absorption ◽  
Inhibited Enzyme

scholarly journals The nickel ion environment in jack bean urease

1984 ◽  
Vol 220 (2) ◽  
pp. 591-595 ◽  
Author(s):  
L Alagna ◽  
S S Hasnain ◽  
B Piggott ◽  
D J Williams
Keyword(s):  
Fine Structure ◽  
Structure Study ◽  
Jack Bean Urease ◽  
Model Compounds ◽  
Deprotonated Form ◽  
Nickel Ion ◽  
Edge Structure ◽  
Jack Bean ◽  
X Ray ◽  
X Ray Absorption

Preliminary results of an extended X-ray absorption fine structure (e.x.a.f.s.) and X-ray absorption near edge structure study of jack bean urease have recently been reported [Hasnain & Piggott (1983) Biochem. Biophys. Res. Commun. 112, 279]. These results indicate that the environment of the nickel ion in the enzyme is similar to that in the model compounds Ni(L)2(L')1(ClO4)1 (where L is 1-n-propyl-2-alpha-hydroxybenzylbenzimidazole and L' is the deprotonated form) and Ni(HMB)3(Br)2 (where HMB is 2-hydroxymethylbenzimidazole), the closest similarity being with Ni(L)2-(L')1(ClO4)1. A detailed e.x.a.f.s. analysis has now been carried out and the crystal structures of the two model compounds solved. These results are reported here.

Crystallization and preliminary X-ray structure determination of jack bean urease with a bound antibody fragment

2002 ◽  
Vol 58 (2) ◽  
pp. 374-376 ◽  
Author(s):  
Louisa Sheridan ◽  
Carrie M. Wilmot ◽  
Karen D. Cromie ◽  
Paul van der Logt ◽  
Simon E. V. Phillips
Keyword(s):  
Structure Determination ◽  
Antibody Fragment ◽  
Jack Bean Urease ◽  
Jack Bean ◽  
X Ray

Jack bean urease (EC 3.5.1.5). III. The involvement of active-site nickel ion in inhibition by β-mercaptoethanol, phosphoramidate, and fluoride

1980 ◽  
Vol 58 (6) ◽  
pp. 481-488 ◽  
Author(s):  
Nicholas E. Dixon ◽  
Robert L. Blakeley ◽  
Burt Zerner
Keyword(s):  
Dissociation Constant ◽  
Active Site ◽  
Competitive Inhibitor ◽  
Jack Bean Urease ◽  
Nickel Ion ◽  
Nickel Ions ◽  
Jack Bean ◽  
Complex Fluoride ◽  
Spectral Changes ◽  
Hydrolysis Of

Interaction of β-mercaptoethanol with urease produces large, rapid and fully reversible spectral changes in that part of the electronic absorption spectrum which is associated with the tightly bound nickel ions. The spectrophotometrically determined value of the dissociation constant of the β-mercaptoethanol–urease complex (0.95 ± 0.05 mM at pH 7.12 and 25 °C) is in agreement with the Ki (0.72 ± 0.26 mM) for β-mercaptoethanol acting as a competitive inhibitor in the hydrolysis of urea. This constitutes direct evidence that the nickel in jack bean urease is at the active site. Inhibition of urease by phosphoramidate is slowly achieved and slowly reversed, and upon reactivation of the isolated phosphoramidate–urease complex, phosphoramidate is regenerated in good yield. Spectrophotometric experiments indicate that phosphoramidate binds to nickel ion in urease. Competition with β-mercaptoethanol was used to determine a dissociation constant (1.23 ± 0.10 mM at pH 7.12 and 25 °C) for a fluoride–urease complex in which fluoride ion also coordinates with an active-site nickel ion. Kinetic evidence is presented which indicates that in the presence of urea, a ternary complex (fluoride–urea–urease) is formed.

X-ray absorption spectroscopic evidence for a unique nickel site in Clostridium thermoaceticum carbon monoxide dehydrogenase

1987 ◽  
Vol 26 (15) ◽  
pp. 2477-2479 ◽  
Author(s):  
Stephen P. Cramer ◽  
Marly K. Eidsness ◽  
W. H. Pan ◽  
Thomas A. Morton ◽  
Steve W. Ragsdale ◽  
...  
Keyword(s):  
Carbon Monoxide ◽  
Carbon Monoxide Dehydrogenase ◽  
Clostridium Thermoaceticum ◽  
Spectroscopic Evidence ◽  
X Ray ◽  
X Ray Absorption
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