scholarly journals Catalytic and Structural Role of a Conserved Active Site Histidine in Berberine Bridge Enzyme

Biochemistry ◽  
2012 ◽  
Vol 51 (31) ◽  
pp. 6139-6147 ◽  
Author(s):  
Silvia Wallner ◽  
Andreas Winkler ◽  
Sabrina Riedl ◽  
Corinna Dully ◽  
Stefanie Horvath ◽  
...  
Keyword(s):  
Active Site ◽  
Structural Role ◽  
Berberine Bridge Enzyme ◽  
Active Site Histidine

scholarly journals Structural role of the active-site metal in the conformation of Trypanosoma brucei phosphoglycerate mutase

FEBS Journal ◽  
2012 ◽  
Vol 279 (11) ◽  
pp. 2012-2021 ◽  
Author(s):  
Gustavo F. Mercaldi ◽  
Humberto M. Pereira ◽  
Artur T. Cordeiro ◽  
Paul A. M. Michels ◽  
Otavio H. Thiemann
Keyword(s):  
Trypanosoma Brucei ◽  
Active Site ◽  
Phosphoglycerate Mutase ◽  
Structural Role

scholarly journals Catalytic role of the active site histidine of porcine pancreatic phospholipase A2 probed by the variants H48Q, H48N and H48K

1999 ◽  
Vol 12 (6) ◽  
pp. 497-503 ◽  
Author(s):  
Marcel J.W. Janssen ◽  
Wendy A.E.C. van de Wiel ◽  
Sigrid H.W. Beiboer ◽  
Muriel D. van Kampen ◽  
Hubertus M. Verheij ◽  
...  
Keyword(s):  
Phospholipase A2 ◽  
Active Site ◽  
Pancreatic Phospholipase ◽  
Pancreatic Phospholipase A2 ◽  
Catalytic Role ◽  
Active Site Histidine

scholarly journals Structural and catalytic effects of an invariant purine substitution in the hammerhead ribozyme: implications for the mechanism of acid–base catalysis

2014 ◽  
Vol 70 (9) ◽  
pp. 2256-2263 ◽  
Author(s):  
Eric P. Schultz ◽  
Ernesto E. Vasquez ◽  
William G. Scott
Keyword(s):  
Active Site ◽  
Metal Ion ◽  
Hammerhead Ribozyme ◽  
Base Catalysis ◽  
Metal Ion Binding ◽  
Acid Base ◽  
Kinetic Measurements ◽  
Structural Role ◽  
General Base

The hammerhead ribozyme catalyzes RNA cleavageviaacid–base catalysis. Whether it does so by general acid–base catalysis, in which the RNA itself donates and abstracts protons in the transition state, as is typically assumed, or by specific acid–base catalysis, in which the RNA plays a structural role and proton transfer is mediated by active-site water molecules, is unknown. Previous biochemical and crystallographic experiments implicate an invariant purine in the active site, G12, as the general base. However, G12 may play a structural role consistent with specific base catalysis. To better understand the role of G12 in the mechanism of hammerhead catalysis, a 2.2 Å resolution crystal structure of a hammerhead ribozyme fromSchistosoma mansoniwith a purine substituted for G12 in the active site of the ribozyme was obtained. Comparison of this structure (PDB entry 3zd4), in which A12 is substituted for G, with three previously determined structures that now serve as important experimental controls, allows the identification of structural perturbations that are owing to the purine substitution itself. Kinetic measurements for G12 purine-substituted schistosomal hammerheads confirm a previously observed dependence of rate on the pKaof the substituted purine; in both cases inosine, which is similar to G in pKaand hydrogen-bonding properties, is unexpectedly inactive. Structural comparisons indicate that this may primarily be owing to the lack of the exocyclic 2-amino group in the G12A and G12I substitutions and its structural effect upon both the nucleotide base and phosphate of A9. The latter involves the perturbation of a previously identified and well characterized metal ion-binding site known to be catalytically important in both minimal and full-length hammerhead ribozyme sequences. The results permit it to be suggested that G12 plays an important role in stabilizing the active-site structure. This result, although not inconsistent with the potential role of G12 as a general base, indicates that an alternative hammerhead cleavage mechanism involving specific base catalysis may instead explain the observed rate dependence upon purine substitutions at G12. The crystallographic results, contrary to previous assumptions, therefore cannot be interpreted to favor the general base catalysis mecahnism over the specific base catalysis mechanism. Instead, both of these mutually exclusive mechanistic alternatives must be considered in light of the current structural and biochemical data.

Structural role of the copper ions in the dinuclear active site of Carcinus aestuarii hemocyanin

Micron ◽  
2004 ◽  
Vol 35 (1-2) ◽  
pp. 43-44 ◽  
Author(s):  
S Gatto ◽  
V De Filippis ◽  
F Spinozzi ◽  
P Di Muro ◽  
L Bubacco ◽  
...  
Keyword(s):  
Active Site ◽  
Copper Ions ◽  
Structural Role

scholarly journals Evidence for a Dual Role of an Active Site Histidine in α-Amino-β-carboxymuconate-ε-semialdehyde Decarboxylase

Biochemistry ◽  
2012 ◽  
Vol 51 (29) ◽  
pp. 5811-5821 ◽  
Author(s):  
Lu Huo ◽  
Andrew J. Fielding ◽  
Yan Chen ◽  
Tingfeng Li ◽  
Hiroaki Iwaki ◽  
...  
Keyword(s):  
Active Site ◽  
Dual Role ◽  
Active Site Histidine
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