Mechanism-based isocoumarin inhibitors for serine proteases: Use of active site structure and substrate specificity in inhibitor design

1989 ◽  
Vol 39 (1) ◽  
pp. 33-46 ◽  
Author(s):  
James C. Powers ◽  
Chih-Min Kam ◽  
Lakshmi Narasimhan ◽  
Joszef Oleksyszyn ◽  
Maria A. Hernandez ◽  
...  
Keyword(s):  
Substrate Specificity ◽  
Active Site ◽  
Serine Proteases ◽  
Inhibitor Design ◽  
Site Structure ◽  
Active Site Structure

scholarly journals Determinants of the substrate specificity of human cytochrome P-450 CYP2D6: design and construction of a mutant with testosterone hydroxylase activity

1998 ◽  
Vol 331 (3) ◽  
pp. 783-792 ◽  
Author(s):  
Gillian SMITH ◽  
Sandeep MODI ◽  
Ilona PILLAI ◽  
Lu-Yun LIAN ◽  
Michael J. SUTCLIFFE ◽  
...  
Keyword(s):  
Amino Acid ◽  
Substrate Specificity ◽  
Active Site ◽  
Homology Modelling ◽  
Structural Basis ◽  
Site Structure ◽  
Catalytic Selectivity ◽  
Active Site Structure ◽  
Debrisoquine Hydroxylase ◽  
Cytochrome P 450

Cytochrome P-450 CYP2D6, human debrisoquine hydroxylase, metabolizes more than 30 prescribed drugs, the vast majority of which are small molecules containing a basic nitrogen atom. In contrast, the similar mouse protein Cyp2d-9 was first characterized as a testosterone 16α-hydroxylase. No common substrates have been reported for the two enzymes. Here we investigate the structural basis of this difference in substrate specificity. We have earlier used a combination of NMR data and homology modelling to generate a three-dimensional model of CYP2D6 [Modi, Paine, Sutcliffe, Lian, Primrose, Wolf, C. R. and Roberts (1996) Biochemistry 35, 4541–4550]. We have now generated a homology model of Cyp2d-9 and compared the two models to identify specific amino acid residues that we believe form the substrate-binding site in each protein and therefore influence catalytic selectivity. Although there are many similarities in active site structure, the most notable difference is a phenylalanine residue (Phe-483) in CYP2D6, which in the model is located such that the bulky phenyl ring is positioned across the channel mouth, thus limiting the size of substrate that can access the active site. In Cyp2d-9, the corresponding position is occupied by an isoleucine residue, which imposes fewer steric restraints on the size of substrate that can access the active site. To investigate whether the amino acid residue at this position does indeed influence the catalytic selectivity of these enzymes, site-directed mutagenesis was used to change Phe-483 in CYP2D6 to isoleucine and also to tryptophan. CYP2D6, Cyp2d-9 and both mutant CYP2D6 proteins were co-expressed with NADPH cytochrome P-450 reductase as a functional mono-oxygenase system in Escherichia coliand their relative catalytic activities towards bufuralol and testosterone were determined. All four proteins exhibited catalytic activity towards bufuralol but only Cyp2d-9 catalysed the formation of 16α-hydroxytesterone. Uniquely, the CYP2D6F483I mutant acquired the ability to metabolize testosterone to a novel product, which was identified by MS and proton NMR spectroscopy as 15α-hydroxytestosterone. NMR spin relaxation experiments were used to measure distances between the haem iron and protons of testosterone bound to the CYP2D6F483I mutant. These experiments demonstrate that very minor modifications to the active site structure of CYP2D6 can have a profound influence on the substrate specificity of the enzyme.

Active site structure and catalytic mechanisms of human peroxidases

2006 ◽  
Vol 445 (2) ◽  
pp. 199-213 ◽  
Author(s):  
Paul G. Furtmüller ◽  
Martina Zederbauer ◽  
Walter Jantschko ◽  
Jutta Helm ◽  
Martin Bogner ◽  
...  
Keyword(s):  
Active Site ◽  
Site Structure ◽  
Active Site Structure ◽  
Catalytic Mechanisms

scholarly journals Iron-Imprinted Single-Atomic Site Catalyst-Based Nanoprobe for Detection of Hydrogen Peroxide in Living Cells

2021 ◽  
Vol 13 (1) ◽  
Author(s):  
Zhaoyuan Lyu ◽  
Shichao Ding ◽  
Maoyu Wang ◽  
Xiaoqing Pan ◽  
Zhenxing Feng ◽  
...  
Keyword(s):  
Hydrogen Peroxide ◽  
Active Site ◽  
Single Atom ◽  
Site Structure ◽  
Atomic Site ◽  
Ion Imprinting ◽  
Active Site Structure ◽  
In Situ Detection ◽  
Colorimetric Biosensing

AbstractFe-based single-atomic site catalysts (SASCs), with the natural metalloproteases-like active site structure, have attracted widespread attention in biocatalysis and biosensing. Precisely, controlling the isolated single-atom Fe-N-C active site structure is crucial to improve the SASCs’ performance. In this work, we use a facile ion-imprinting method (IIM) to synthesize isolated Fe-N-C single-atomic site catalysts (IIM-Fe-SASC). With this method, the ion-imprinting process can precisely control ion at the atomic level and form numerous well-defined single-atomic Fe-N-C sites. The IIM-Fe-SASC shows better peroxidase-like activities than that of non-imprinted references. Due to its excellent properties, IIM-Fe-SASC is an ideal nanoprobe used in the colorimetric biosensing of hydrogen peroxide (H2O2). Using IIM-Fe-SASC as the nanoprobe, in situ detection of H2O2 generated from MDA-MB-231 cells has been successfully demonstrated with satisfactory sensitivity and specificity. This work opens a novel and easy route in designing advanced SASC and provides a sensitive tool for intracellular H2O2 detection.

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