Search results for "Endopeptidases"
showing 10 items of 285 documents
"RKKH" peptides from the snake venom metalloproteinase of Bothrops jararaca bind near the metal ion-dependent adhesion site of the human integrin alp…
1999
Integrin alpha(1)beta(1) and alpha(2)beta(1) are the major cellular receptors for collagen, and collagens bind to these integrins at the inserted I-domain in their alpha subunit. We have previously shown that a cyclic peptide derived from the metalloproteinase domain of the snake venom protein jararhagin blocks the collagen-binding function of the alpha(2) I-domain. Here, we have optimized the structure of the peptide and identified the site where the peptide binds to the alpha(2) I-domain. The peptide sequence Arg-Lys-Lys-His is critical for recognition by the I-domain, and five negatively charged residues surrounding the "metal ion-dependent adhesion site" (MIDAS) of the I-domain, when mu…
News from an Ancient World: Two Novel Astacin Metalloproteases from the Horseshoe Crab
2008
In this work, we report the cloning, heterologous expression, and characterization of two novel astacin proteases from the chelicerate Limulus polyphemus (horseshoe crab), designated as LAST (Limulus astacin) and LAST_MAM (Limulus astacin containing a MAM domain), respectively. The expression pattern showed ubiquitous occurrence of LAST_MAM, while LAST was predominantly restricted to the eyes and brain, indicating a function in the nervous system. Both enzymes contain the characteristic metzincin-type zinc-binding region and Met turn. While LAST is made up only of the typical prodomain and astacin-like protease domain, LAST_MAM contains an additional MAM (meprin A5 protein tyrosine phosphat…
Tuning and Predicting Biological Affinity: Aryl Nitriles as Cysteine Protease Inhibitors
2012
A series of aryl nitrile-based ligands were prepared to investigate the effect of their electrophilicity on the affinity against the cysteine proteases rhodesain and human cathepsin L. Density functional theory calculations provided relative reactivities of the nitriles, enabling prediction of their biological affinity and cytotoxicity and a clear structure-activity relationship.
Flavonoids as noncompetitive inhibitors of Dengue virus NS2B-NS3 protease: Inhibition kinetics and docking studies
2014
NS2B-NS3 is a serine protease of the Dengue virus considered a key target in the search for new antiviral drugs. In this study flavonoids were found to be inhibitors of NS2B-NS3 proteases of the Dengue virus serotypes 2 and 3 with IC50 values ranging from 15 to 44 μM. Agathisflavone (1) and myricetin (4) turned out to be noncompetitive inhibitors of dengue virus serotype 2 NS2B-NS3 protease with Ki values of 11 and 4.7 μM, respectively. Docking studies propose a binding mode of the flavonoids in a specific allosteric binding site of the enzyme. Analysis of biomolecular interactions of quercetin (5) with NT647-NHS-labeled Dengue virus serotype 3 NS2B-NS3 protease by microscale thermophoresis…
Evidence for substrate binding-induced zwitterion formation in the catalytic Cys-His dyad of the SARS-CoV main protease.
2014
The coronavirus main protease (M(pro)) represents an attractive drug target for antiviral therapy of coronavirus (CoV) infections, including severe acute respiratory syndrome (SARS). The SARS-CoV M(pro) and related CoV proteases have several distinct features, such as an uncharged Cys-His catalytic dyad embedded in a chymotrypsin-like protease fold, that clearly separate these enzymes from archetypical cysteine proteases. To further characterize the catalytic system of CoV main proteases and to obtain information about improved inhibitors, we performed comprehensive simulations of the proton-transfer reactions in the SARS-CoV M(pro) active site that lead to the Cys(-)/His(+) zwitterionic st…
Structural basis for the sheddase function of human meprin β metalloproteinase at the plasma membrane.
2012
Ectodomain shedding at the cell surface is a major mechanism to regulate the extracellular and circulatory concentration or the activities of signaling proteins at the plasma membrane. Human meprin β is a 145-kDa disulfide-linked homodimeric multidomain type-I membrane metallopeptidase that sheds membrane-bound cytokines and growth factors, thereby contributing to inflammatory diseases, angiogenesis, and tumor progression. In addition, it cleaves amyloid precursor protein (APP) at the β-secretase site, giving rise to amyloidogenic peptides. We have solved the X-ray crystal structure of a major fragment of the meprin β ectoprotein, the first of a multidomain oligomeric transmembrane sheddase…
Jararhagin-derived RKKH Peptides Induce Structural Changes in α1I Domain of Human Integrin α1β1
2003
Integrin alpha(1)beta(1) is one of four collagen-binding integrins in humans. Collagens bind to the alphaI domain and in the case of alpha(2)I collagen binding is competitively inhibited by peptides containing the RKKH sequence and derived from the metalloproteinase jararhagin of snake venom from Bothrops jararaca. In alpha(2)I, these peptides bind near the metal ion-dependent adhesion site (MIDAS), where a collagen (I)-like peptide is known to bind; magnesium is required for binding. Published structures of the ligand-bound "open" conformation of alpha(2)I differs significantly from the "closed" conformation seen in the structure of apo-alpha(2)I near MIDAS. Here we show that two peptides,…
Cis autocatalytic cleavage of glycine-linked Zika virus NS2B-NS3 protease constructs.
2019
The flaviviral heterodimeric serine protease NS2B-NS3, consisting of the NS3 protease domain and the NS2B co-factor, is essential for ZIKA virus maturation and replication in cells. For in vitro studies a 'linked' construct, where a polyglycine linker connects NS2BCF and NS3pro , is often used. This construct undergoes autocatalytic cleavage. Here, we show that linked ZIKV NS2BCF -NS3pro is cleaved in cis in the NS2BCF exclusively at position R95 and not at the previously proposed alternate cleavage site at residue R29 in the NS3pro . Cleavage neither affects protease stability nor activity, despite some observed differences in spectroscopic behavior. This minimally modified construct may t…
The NS3/4A proteinase of the hepatitis C virus: unravelling structure and function of an unusual enzyme and a prime target for antiviral therapy
1999
The hepatitis C virus (HCV) is a major causative agent of transfusion-acquired and sporadic non-A, non-B hepatitis worldwide. Infections most often persist and lead, in approximately 50% of all patients, to chronic liver disease. As is characteristic for a member of the family Flaviviridae, HCV has a plus-strand RNA genome encoding a polyprotein, which is cleaved co- and post-translationally into at least 10 different products. These cleavages are mediated, among others, by a virally encoded chymotrypsin-like serine proteinase located in the N-terminal domain of non-structural protein 3 (NS3). Activity of this enzyme requires NS4A, a 54-residue polyprotein cleavage product, to form a stable…
Sortase A Inhibitors: Recent Advances and Future Perspectives
2015
Here, we describe the most promising small synthetic organic compounds that act as potent Sortase A inhibitors and cater the potential to be developed as antivirulence drugs. Sortase A is a polypeptide of 206 amino acids, which catalyzes two sequential reactions: (i) thioesterification and (ii) transpeptidation. Sortase A is involved in the process of bacterial adhesion by anchoring LPXTG-containing proteins to lipid II. Sortase A inhibitors do not affect bacterial growth, but they restrain the virulence of pathogenic bacterial strains, thereby preventing infections caused by Staphylococcus aureus or other Gram-positive bacteria. The efficacy of the most promising inhibitors needs to be com…