scholarly journals Contributions of Unique Active Site Residues of Eukaryotic UDP-Galactopyranose Mutases to Substrate Recognition and Active Site Dynamics

Biochemistry ◽  
2014 ◽  
Vol 53 (49) ◽  
pp. 7794-7804 ◽  
Author(s):  
Isabel Da Fonseca ◽  
Insaf A. Qureshi ◽  
Ritcha Mehra-Chaudhary ◽  
Karina Kizjakina ◽  
John J. Tanner ◽  
...  
Keyword(s):  
Active Site ◽  
Substrate Recognition ◽  
Active Site Residues

Differential Contribution of Active Site Residues in Substrate Recognition Sites 1 and 5 to Cytochrome P450 2C8 Substrate Selectivity and Regioselectivity†

Biochemistry ◽  
2004 ◽  
Vol 43 (24) ◽  
pp. 7834-7842 ◽  
Author(s):  
Oranun Kerdpin ◽  
David J. Elliot ◽  
Sanford L. Boye ◽  
Donald J. Birkett ◽  
Krongtong Yoovathaworn ◽  
...  
Keyword(s):  
Cytochrome P450 ◽  
Active Site ◽  
Substrate Recognition ◽  
Substrate Selectivity ◽  
Active Site Residues ◽  
Recognition Sites ◽  
Cytochrome P450 2C8 ◽  
Differential Contribution

scholarly journals CYP2E1 active site residues in substrate recognition sequence 5 identified by photoaffinity labeling and homology modeling

2007 ◽  
Vol 459 (1) ◽  
pp. 59-69 ◽  
Author(s):  
Samuel L. Collom ◽  
Arvind P. Jamakhandi ◽  
Alan J. Tackett ◽  
Anna Radominska-Pandya ◽  
Grover P. Miller
Keyword(s):  
Homology Modeling ◽  
Active Site ◽  
Substrate Recognition ◽  
Photoaffinity Labeling ◽  
Active Site Residues ◽  
Recognition Sequence

scholarly journals Characterization of glutamyl-tRNA–dependent dehydratases using nonreactive substrate mimics

2019 ◽  
Vol 116 (35) ◽  
pp. 17245-17250 ◽  
Author(s):  
Ian R. Bothwell ◽  
Dillon P. Cogan ◽  
Terry Kim ◽  
Christopher J. Reinhardt ◽  
Wilfred A. van der Donk ◽  
...  
Keyword(s):  
Amino Acids ◽  
Active Site ◽  
Substrate Recognition ◽  
Peptide Substrate ◽  
Active Site Residues ◽  
Food Preservative ◽  
Linear Peptide ◽  
Development Of Resistance ◽  
Subsequent Elimination

The peptide natural product nisin has been used as a food preservative for 6 decades with minimal development of resistance. Nisin contains the unusual amino acids dehydroalanine and dehydrobutyrine, which are posttranslationally installed by class I lanthipeptide dehydratases (LanBs) on a linear peptide substrate through an unusual glutamyl-tRNA–dependent dehydration of Ser and Thr. To date, little is known about how LanBs catalyze the transfer of glutamate from charged tRNAGlu to the peptide substrate, or how they carry out the subsequent elimination of the peptide-glutamyl adducts to afford dehydro amino acids. Here, we describe the synthesis of inert analogs that mimic substrate glutamyl-tRNAGlu and the glutamylated peptide intermediate, and determine the crystal structures of 2 LanBs in complex with each of these compounds. Mutational studies were used to characterize the function of the glutamylation and glutamate elimination active-site residues identified through the structural analysis. These combined studies provide insights into the mechanisms of substrate recognition, glutamylation, and glutamate elimination by LanBs to effect a net dehydration reaction of Ser and Thr.

Development of Xanthine Based Inhibitors Targeting Phosphodiesterase 9A

2017 ◽  
Vol 14 (10) ◽  
pp. 1122-1137 ◽  
Author(s):  
Nivedita Singh ◽  
Parameswaran Saravanan ◽  
M.S. Thakur ◽  
Sanjukta Patra
Keyword(s):  
Free Energy ◽  
Active Site ◽  
Signal Transduction Pathway ◽  
Docking Study ◽  
Primary Objective ◽  
Cgmp Level ◽  
Active Site Residues ◽  
Aromatic Fragment ◽  
Docking Approach ◽  
Free Energy Of Binding

Background: Phosphodiesterases 9A (PDE9A) is one of the prominent regulating enzymes of the signal transduction pathway having highest catalytic affinity for second messenger, cGMP. When the cGMP level is lowered, an uncontrolled expression of PDE9A may lead to various neurodegenerative diseases. To regulate the catalytic activity of PDE9A, potent inhibitors are needed. Objective: The primary objective of the present study was to develop new xanthine based inhibitors targeting PDE9A. This study was an attempt to bring structural diversification in PDE9A inhibitor development because most of the existing inhibitors are constructed over pyrazolopyrimidinone scaffold. Methods: Manual designing and parallel molecular docking approach were used for the development of xanthine derivatives. In this study, N1, N3, N9 and C8 positions of xanthine scaffold were selected as substitution sites to design 200 new compounds. Reverse docking and pharmaceutical analyses were used for final validation of most promising compounds. Results: By keeping free energy of binding cut-off of -6.0 kcal/mol, 52 compounds were screened. The compounds with substitution at N1, N3 and C8 positions of xanthine showed good occupancy in PDE9A active site pocket with a significant interaction pattern. This was further validated by screening different factors such as free energy of binding, inhibition constant and interacting active site residues in the 5Å region. Substitution at C8 position with phenyl substituent determined the inhibition affinity of compounds towards PDE9A by establishing a strong hydrophobic - hydrophobic interaction. The alkyl chain at N1 position generated selectivity of compounds towards PDE9A. The aromatic fragment at N3 position increased the binding affinity of compounds. Thus, by comparative docking study, it was found that compound 39-42 formed selective interaction towards PDE9A over other members of the PDE superfamily. Conclusion: From the present study, N1, N3 and C8 positions of xanthine were concluded as the best sites for substitution for the generation of potent PDE9A inhibitors.

scholarly journals An enzymatic activation of formaldehyde for nucleotide methylation

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Charles Bou-Nader ◽  
Frederick W. Stull ◽  
Ludovic Pecqueur ◽  
Philippe Simon ◽  
Vincent Guérineau ◽  
...  
Keyword(s):  
Amino Acids ◽  
Thymidylate Synthase ◽  
Active Site ◽  
De Novo ◽  
Crystallographic Structure ◽  
De Novo Synthesis ◽  
Active Site Residues ◽  
Enzymatic Activation ◽  
Enzyme Cofactors ◽  
Unique Ability

AbstractFolate enzyme cofactors and their derivatives have the unique ability to provide a single carbon unit at different oxidation levels for the de novo synthesis of amino-acids, purines, or thymidylate, an essential DNA nucleotide. How these cofactors mediate methylene transfer is not fully settled yet, particularly with regard to how the methylene is transferred to the methylene acceptor. Here, we uncovered that the bacterial thymidylate synthase ThyX, which relies on both folate and flavin for activity, can also use a formaldehyde-shunt to directly synthesize thymidylate. Combining biochemical, spectroscopic and anaerobic crystallographic analyses, we showed that formaldehyde reacts with the reduced flavin coenzyme to form a carbinolamine intermediate used by ThyX for dUMP methylation. The crystallographic structure of this intermediate reveals how ThyX activates formaldehyde and uses it, with the assistance of active site residues, to methylate dUMP. Our results reveal that carbinolamine species promote methylene transfer and suggest that the use of a CH2O-shunt may be relevant in several other important folate-dependent reactions.

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