Search PubMedSearch

PubMed · 7765173

Engineering proteases with altered specificity.

Abstract

Recent analysis of the crystal structures, both of the retroviral aspartyl proteases from Rous sarcoma virus and human immunodeficiency virus type 1 and of the serine proteases subtilisin and alpha-lytic protease, has enabled the rational design of mutations in the substrate-binding pocket of these enzymes. Alterations in steady-state kinetic properties of the purified mutant enzymes have been detected in vitro by following the cleavage of synthetic peptide substrates. These analyses have identified key amino acid residues in each of these enzymes that are involved in substrate specificity, and they have provided the foundation for the design of proteases with novel substrate specificities.

Explore related subjects

Keep this discovery

Explore connections, maps & timelines

BibTeXRIS

J P Leis, C E Cameron. 1994. Engineering proteases with altered specificity.. https://doi.org/10.1016/0958-1669(94)90049-3

Cite the original work for its findings. Save a collection to share your selection of sources.

KEEP EXPLORING

Related citations

Dual plasmepsin IX and X inhibitors are refractory to development of resistance.

Artemisinin-based combination therapies (ACTs) remain the cornerstone of malaria treatment, but emerging resistance threatens their efficacy. The potential for the development of drug resistance against plasmepsin X (PMX)-selective inhibitors and dual plasmepsin IX/X (PMIX/X) inhibitors was investigated in Plasmodium falciparum. A series of PMX-selective (WM4, WM76, WM92) and PMIX/X dual inhibitors (WM382, WM09, WM42) were characterised for potency against parasite growth and enzyme inhibition. In vitro selection experiments showed that all compounds had a high barrier to resistance, although parasites with reduced sensitivity to PMX‑selective inhibitors could still be selected. Resistance mechanisms involved pmx gene amplification and point mutations (D245N, S315P, S359P, I363L) that alter inhibitor binding. Recombinant expression and Michaelis-Menten kinetics demonstrated that these mutations impair drug binding whilst preserving PMX catalytic function. Reverse genetics confirmed that introducing these mutations into the pmx gene resulted in decreased potency of the inhibitors. In this study, resistance to the PMIX/X dual inhibitors evaluated here could not be selected, despite prolonged selection pressure. Antimalarial Resistome Barcoding (AReBar) assays confirmed the absence of pre-existing resistance to either inhibitor class. Critically, PMIX/X dual inhibitors maintained efficacy against parasites with decreased sensitivity to PMX-selective compounds. These findings demonstrate that dual PMIX/X inhibitors present a substantially higher barrier to resistance than PMX-selective inhibitors, informing antimalarial drug development strategies and highlighting dual-target inhibition as a promising approach to mitigate resistance risks.

Aspartic Acid Endopeptidases

Evidence for intracellular endothelin-converting enzyme-2 expression in cultured human vascular endothelial cells.

We have previously reported the intracellular localization of the endothelin-converting enzyme-1 (ECE-1) in human umbilical vein endothelial cells. In the present study, we provide the first immunocytochemical and biochemical evidence for the presence of ECE-2 in human cells. ECE activity was determined by conversion of exogenously added big endothelin-1 (big ET-1) to ET-1 in subcellular fractions obtained by sucrose density gradient centrifugation of human umbilical vein endothelial cell homogenates. ECE-1 and ECE-2 can be differentiated by pH dependence for optimal activity and by sensitivity to phosphoramidon, which shows selectivity for ECE-2 over ECE-1 and PD159790, a novel ECE-1 selective inhibitor. Optimal ECE activity was measured at pH 6.0, a value intermediate between that reported for ECE-1 (pH 6.8) and ECE-2 (pH 5.5), indicating expression of both enzymes. At pH 6.9, conversion of big ET-1 was inhibited markedly by 30 micromol/L PD159790 and by 100 micromol/L phosphoramidon but not by 0.1 micromol/L phosphoramidon. In contrast, ECE activity was unaffected by 30 micromol/L PD159790 but was inhibited markedly by 0.1 and 100 micromol/L phosphoramidon at pH 5. 4 (IC50 1.5 nmol/L), consistent with ECE-2 activity. Confocal microscopy revealed a punctate pattern of ECE-2-like immunoreactive staining in the cell cytosol, suggesting localization to secretory vesicles with a possible role in processing big ET-1 while in transit to the cell surface via the constitutive secretory pathway.

Aspartic Acid Endopeptidases

Expression of endothelin-1, endothelin-converting enzyme, and endothelin receptors in chronic heart failure.

BACKGROUND: Elevated plasma levels of endothelin (ET)-1 have been reported in association with heart diseases, including heart failure. Furthermore, it has been suggested that ET-1 acts as a local autocrine/paracrine factor with biological activities such as vasoconstriction, mitogenesis, and inotropic effects on the heart. This study investigated alterations of ET-1, ET receptor, and endothelin-converting enzyme (ECE) expression in left ventricular myocardium from patients with end-stage heart failure. METHODS AND RESULTS: mRNA concentrations of ETA and ETB receptors, prepro-ET-1 (ppET-1), and ECE in left ventricles from nonfailing donors hearts (NF) and from patients with end-stage chronic heart failure (NYHA functional class IV) due to dilated cardiomyopathy (DCM) were compared by use of a competitive reverse transcription-polymerase chain reaction technique. There was no significant difference in mRNA expression for ppET-1, ECE-1, and ETA receptors, whereas a significant reduction of ETB-receptor mRNA was observed in DCM hearts. 125I-labeled ET-1 radioligand binding studies demonstrated a significant downregulation of ETB receptors, whereas ETA-receptor density was increased in membranes from DCM hearts. Phosphoramidon-sensitive ECE activity and immunodetectable amounts of ECE protein in left ventricular membrane preparations did not differ between NF and DCM hearts. Finally, immunoreactive ET-1 concentrations were increased in DCM hearts. CONCLUSIONS: The present study demonstrates changes in the ET-receptor expression pattern in favor of the ETA receptor in human end-stage heart failure. Furthermore, activation of the cardiac ET system with increased tissue ET-1 concentrations in the failing myocardium is observed. This is more likely due to decreased clearance than to increased synthesis, because ppET-1 gene expression and ECE activity are unchanged.

Aspartic Acid Endopeptidases