Homology modeling and SAR analysis of Schistosoma japonicum cathepsin D (SjCD) with statin inhibitors identify a unique active site steric barrier with potential for the design of specific inhibitors

2005 ◽  
Vol 386 (4) ◽  
pp. 339-349 ◽  
Author(s):  
Conor R. Caffrey ◽  
Lenka Placha ◽  
Cyril Barinka ◽  
Martin Hradilek ◽  
Jiří Dostál ◽  
...  
Keyword(s):  
Schistosoma Japonicum ◽  
Active Site ◽  
Cathepsin D ◽  
Three Dimensional ◽  
Homology Model ◽  
Three Dimensional Model ◽  
Pathogenic Yeast ◽  
Active Site Cleft ◽  
Chronic Morbidity ◽  
Sar Analysis

Abstract Proteases that digest the blood-meal of the parasitic fluke Schistosoma are potential targets for therapy of schistosomiasis, a disease of chronic morbidity in humans. We generated a three-dimensional model of the cathepsin D target protease of Schistosoma japonicum (SjCD) utilizing the crystal structure of human cathepsin D (huCD) in complex with pepstatin as template. A homology model was also generated for the related secreted aspartic protease 2 (SAP2) of the pathogenic yeast, Candida albicans. An initial panel of seven statin inhibitors, originally designed for huCD [Majer et al., Protein Sci. 6 (1997), pp. 1458–1466], was tested against the two pathogen proteases. One inhibitor showed poor reactivity with SjCD. Examination of the SjCD active-site cleft revealed that the poor inhibition was due to a unique steric barrier situated between the S2 and S4 subsites. An in silico screen of 20 potential statin scaffolds with the SjCD model and incorporating the steric barrier constraint was performed. Four inhibitors (SJ1–SJ4) were eventually synthesized and tested with SjCD, bovine CD and SAP2. Of these, SJ2 and SJ3 proved moderately more specific for SjCD over bovine CD, with IC50 values of 15 and 60 nM, respectively. The unique steric barrier identified here provides a structural focus for further development of more specific SjCD inhibitors.

Three-dimensional model and molecular dynamics simulation of the active site of the self-splicing intervening sequence of the bacteriophage T4 nrdB messenger RNA

Biochemistry ◽  
1990 ◽  
Vol 29 (45) ◽  
pp. 10317-10322 ◽  
Author(s):  
Lennart Nilsson ◽  
Agneta Aahgren-Staalhandske ◽  
Ann Sofie Sjoegren ◽  
Solveig Hahne ◽  
Britt Marie Sjoeberg
Keyword(s):  
Molecular Dynamics ◽  
Active Site ◽  
Messenger Rna ◽  
Bacteriophage T4 ◽  
Three Dimensional ◽  
The Self ◽  
Dynamics Simulation ◽  
Dimensional Model ◽  
Three Dimensional Model ◽  
Self Splicing

scholarly journals Structural Features of a Bacteroidetes-Affiliated Cellulase Linked with a Polysaccharide Utilization Locus

2015 ◽  
Vol 5 (1) ◽  
Author(s):  
A.E. Naas ◽  
A.K. MacKenzie ◽  
B. Dalhus ◽  
V.G.H. Eijsink ◽  
P.B. Pope
Keyword(s):  
Active Site ◽  
Three Dimensional ◽  
Structural Features ◽  
Structure And Function ◽  
Dimensional Structure ◽  
Active Site Cleft ◽  
Polysaccharide Utilization Locus ◽  
And Function ◽  
Rumen Metagenome

Abstract Previous gene-centric analysis of a cow rumen metagenome revealed the first potentially cellulolytic polysaccharide utilization locus, of which the main catalytic enzyme (AC2aCel5A) was identified as a glycoside hydrolase (GH) family 5 endo-cellulase. Here we present the 1.8 Å three-dimensional structure of AC2aCel5A and characterization of its enzymatic activities. The enzyme possesses the archetypical (β/α)8-barrel found throughout the GH5 family and contains the two strictly conserved catalytic glutamates located at the C-terminal ends of β-strands 4 and 7. The enzyme is active on insoluble cellulose and acts exclusively on linear β-(1,4)-linked glucans. Co-crystallization of a catalytically inactive mutant with substrate yielded a 2.4 Å structure showing cellotriose bound in the −3 to −1 subsites. Additional electron density was observed between Trp178 and Trp254, two residues that form a hydrophobic “clamp”, potentially interacting with sugars at the +1 and +2 subsites. The enzyme’s active-site cleft was narrower compared to the closest structural relatives, which in contrast to AC2aCel5A, are also active on xylans, mannans and/or xyloglucans. Interestingly, the structure and function of this enzyme seem adapted to less-substituted substrates such as cellulose, presumably due to the insufficient space to accommodate the side-chains of branched glucans in the active-site cleft.

Structure and specificity of antibody molecules

1975 ◽  
Vol 272 (915) ◽  
pp. 43-51 ◽  
Keyword(s):  
Active Site ◽  
Three Dimensional ◽  
Crystallographic Analysis ◽  
Spatial Proximity ◽  
Three Dimensional Model ◽  
Fab Fragment ◽  
Active Centre ◽  
Myeloma Protein ◽  
Close Spatial Proximity ◽  
Difference Fourier

The structure of the Fab' fragment of a human myeloma protein (IgG1 (λ) New) has been determined by X-ray crystallographic analysis to a nominal resolution of 0.2 nm. Each of the structure subunits corresponding to the variable and to the constant homology regions of the light and heavy polypeptide chains contains two irregular (3-sheets which are roughly parallel to each other and surround a tightly packed interior of hydrophobic side chains. The regions of the hypervariable sequences in the light and heavy chains occur in close spatial proximity at one end of the molecule, defining the active site of IgG New. The role of these hypervariable regions in defining the size and shape of the active site of different immunoglobulins is discussed on the basis of the three-dimensional model of Fab' New. Several ligands that bind to the active centre of IgG New have been used to obtain crystalline ligand-Fab' New complexes which were investigated by difference Fourier maps. These studies are analysed in terms of the biological function and specificity of antibodies.

scholarly journals Structural Modeling and Site-Directed Mutagenesis of the Actinorhodin β-Ketoacyl-Acyl Carrier Protein Synthase

2000 ◽  
Vol 182 (9) ◽  
pp. 2619-2623 ◽  
Author(s):  
Min He ◽  
Mustafa Varoglu ◽  
David H. Sherman
Keyword(s):  
Amino Acid ◽  
Active Site ◽  
Fatty Acid Synthase ◽  
Acyl Carrier Protein ◽  
Three Dimensional ◽  
Site Directed Mutagenesis ◽  
Directed Mutagenesis ◽  
Three Dimensional Model ◽  
Catalytic Active Site ◽  
Ketoacyl Synthase

ABSTRACT A three-dimensional model of the Streptomyces coelicolor actinorhodin β-ketoacyl synthase (Act KS) was constructed based on the X-ray crystal structure of the relatedEscherichia coli fatty acid synthase condensing enzyme β-ketoacyl synthase II, revealing a similar catalytic active site organization in these two enzymes. The model was assessed by site-directed mutagenesis of five conserved amino acid residues in Act KS that are in close proximity to the Cys169 active site. Three substitutions completely abrogated polyketide biosynthesis, while two replacements resulted in significant reduction in polyketide production. 3H-cerulenin labeling of the various Act KS mutant proteins demonstrated that none of the amino acid replacements affected the formation of the active site nucleophile.

scholarly journals A Three-dimensional Model of the Neprilysin 2 Active Site Based on the X-ray Structure of Neprilysin

2004 ◽  
Vol 279 (44) ◽  
pp. 46172-46181 ◽  
Author(s):  
Stéphanie Voisin ◽  
Didier Rognan ◽  
Claude Gros ◽  
Tanja Ouimet
Keyword(s):  
Active Site ◽  
Three Dimensional ◽  
Physiological Role ◽  
Site Directed Mutagenesis ◽  
Three Dimensional Model ◽  
X Ray ◽  
Amide Bonds ◽  
Inhibitory Compounds ◽  
Proposed Model

Neprilysin 2 (NEP2), a recently identified member of the M13 subfamily of metalloproteases, shares the highest degree of homology with the prototypical member of the family neprilysin. Whereas the study of thein vitroenzymatic activity of NEP2 shows that it resembles that of NEP as it cleaves the same substrates often at the same amide bonds and binds the same inhibitory compounds albeit with different potencies, its physiological role remains elusive because of the lack of selective inhibitors. To aid in the design of these novel compounds and better understand the different inhibitory patterns of NEP and NEP2, the x-ray structure of NEP was used as a template to build a model of the NEP2 active site. The results of our modeling suggest that the overall structure of NEP2 closely resembles that of NEP. The model of the active site reveals a 97% sequence identity with that of NEP with differences located within the S′2subsite of NEP2 where Ser133and Leu739replace two glycine residues in NEP. To validate the proposed model, site-directed mutagenesis was performed on a series of residues of NEP2, mutants expressed in AtT20 cells, and their ability to bind various substrates and inhibitory compounds was tested. The results confirm the involvement of the conserved Arg131and Asn567in substrate binding and catalytic activity of NEP2 and further show that the modifications in its S′2pocket, particularly the presence therein of Leu739, account for a number of differences in inhibitor binding between NEP and NEP2.

scholarly journals Potential Ebola drug targets – filling the gap: a critical step forward towards the design and discovery of potential drugs

Biologia ◽  
2017 ◽  
Vol 72 (1) ◽  
pp. 1-13 ◽  
Author(s):  
Marissa Balmith ◽  
Mahmoud E.S. Soliman
Keyword(s):  
Binding Site ◽  
Active Site ◽  
Active Sites ◽  
Binding Free Energy ◽  
Three Dimensional ◽  
Computational Prediction ◽  
Homology Model ◽  
Free Energy Calculations ◽  
Biologically Active ◽  
World Health

AbstractAmong the classified neglected infectious diseases, the Ebola virus (EboV) remains a challenging epidemic. This deadly virus has been reported as a category A bioweapon organism by the World Health Organization due to the serious threat it poses. To date, Ebola drug discovery proves challenging. Proteins need to be targeted at the relevant biologically active site for drug or inhibitor binding to be effective. Due to insufficient experimental data to confirm the biologically active binding site for novel protein targets, researchers often rely on computational prediction methods to identify binding sites. Many computational studies have attempted to identify the biological active site for EboV proteins, however, the methods employed are not sufficiently validated. This has prompted us to provide a comprehensive molecular understanding of the various targets of the EboV, including three-dimensional structures, active site identification and further validation. Herein we report the account of a three-dimensional homology model of the unresolved EboV RNA-dependent RNA polymerase (RdRp), as well as a comprehensive analysis of the binding site residues of all proteins of the EboV. Docking-aided active site determination was carried out to identify possible active sites on the homology model of RdRp. Binding free energy calculations revealed subtle differences in the binding at each site. These results can also provide some potential clues for further design of novel inhibitors to treat this killer virus and is a critical cornerstone of research into the EboV.

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