Stabilization of a Transition-State Analogue at the Active Site of Yeast Cytosine Deaminase:  Importance of Proton Transfers

2007 ◽  
Vol 111 (23) ◽  
pp. 6501-6506 ◽  
Author(s):  
Qin Xu ◽  
Haobo Guo ◽  
Andrey Gorin ◽  
Hong Guo
Keyword(s):  
Transition State ◽  
Active Site ◽  
Cytosine Deaminase ◽  
Transition State Analogue ◽  
Proton Transfers ◽  
Yeast Cytosine Deaminase

scholarly journals A Trojan horse transition state analogue generated by MgF3- formation in an enzyme active site

2006 ◽  
Vol 103 (40) ◽  
pp. 14732-14737 ◽  
Author(s):  
N. J. Baxter ◽  
L. F. Olguin ◽  
M. Golicnik ◽  
G. Feng ◽  
A. M. Hounslow ◽  
...  
Keyword(s):  
Transition State ◽  
Active Site ◽  
Trojan Horse ◽  
Enzyme Active Site ◽  
Transition State Analogue

MgF3−and α-Galactose 1-Phosphate in the Active Site of β-Phosphoglucomutase Form a Transition State Analogue of Phosphoryl Transfer

2009 ◽  
Vol 131 (45) ◽  
pp. 16334-16335 ◽  
Author(s):  
Nicola J. Baxter ◽  
Andrea M. Hounslow ◽  
Matthew W. Bowler ◽  
Nicholas H. Williams ◽  
G. Michael Blackburn ◽  
...  
Keyword(s):  
Transition State ◽  
Active Site ◽  
Phosphoryl Transfer ◽  
Transition State Analogue

scholarly journals Antibody-catalyzed formation of a 14-membered ring lactone

2002 ◽  
Vol 80 (12) ◽  
pp. 1643-1645 ◽  
Author(s):  
Michael D Pungente ◽  
Larry Weiler ◽  
Hermann J Ziltener
Keyword(s):  
Monoclonal Antibody ◽  
Transition State ◽  
Active Site ◽  
Large Scale ◽  
Competitive Inhibition ◽  
Membered Ring ◽  
Catalytic Antibodies ◽  
Transition State Analogue ◽  
Catalytic Experiment ◽  
Ether Extraction

Monoclonal antibody (MAb) F123, raised against a macrocyclic phosphonate transition-state analogue, catalyzed an intramolecular transesterification of the corresponding hydroxy ester to give a 14-membered ring lactone. The MAb reaction displayed enzyme-like Michaelis–Menten kinetics with a Km of 255 µM and a kcat of 0.01 min–1 based on p-nitrophenol release and calculated on an active-site basis. Substrate specificity and competitive inhibition by a transition state analogue (Ki = 3 µM) demonstrated that the catalytic activity was associated with binding in the antibody-combining site. The lactone product was isolated from a large-scale catalytic experiment through ether extraction and identified by gas chromatography – mass spectroscopy.Key words: macrocyclization, lactones, catalytic antibodies.

Structure of the Complex of Bovine Pancreatic Phospholipase A2 with a Transition-State Analogue

1998 ◽  
Vol 54 (3) ◽  
pp. 334-341 ◽  
Author(s):  
Kanagaraj Sekar ◽  
Amarendra Kumar ◽  
Xiaohong Liu ◽  
Ming-Daw Tsai ◽  
Michael H. Gelb ◽  
...  
Keyword(s):  
Hydrogen Bonds ◽  
Transition State ◽  
Active Site ◽  
Calcium Ion ◽  
Hydroxyl Group ◽  
Pentagonal Bipyramid ◽  
Water Molecules ◽  
Phosphonate Group ◽  
Pancreatic Phospholipase ◽  
Transition State Analogue

The 1.89 Å resolution structure of the complex of bovine pancreatic phospholipase A2 (PLA2) with the transition-state analogue L-1-O-octyl-2-heptylphosphonyl-sn-glycero-3-phosphoethanolamine (TSA) has been determined. The crystal of the complex is trigonal, space group P3121, a = b = 46.58 and c = 102.91 Å and isomorphous to the native recombinant wild type (WT). The structure was refined to a final crystallographic R value of 18.0% including 957 protein atoms, 88 water molecules, one calcium ion and all 31 non-H atoms of the inhibitor at 1.89 Å resolution. In all, 7 726 reflections [F\gt2\sigma(F)] were used between 8.0 and 1.89 Å resolution. The inhibitor is deeply locked into the active-site cleft and coordinates to the calcium ion by displacing the two water molecules in the calcium pentagonal bipyramid by the anionic O atoms of the phosphate and phosphonate group. The hydroxyl group of Tyr69 hydrogen bonds to the second anionic O atom of the phosphate group while that of the phosphonate group replaces the third water, `catalytic' water, which forms a hydrogen bond to Nδ1 of His48. The fourth water which also shares Nδ1 of His48 is displaced by the steric hinderance of the inhibitor. The fifth conserved structural water is still present in the active site and forms a network of hydrogen bonds with the surrounding residues. The structure is compared with the other known TSA–PLA2 complexes.

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