Structural and kinetic evidence of aging after organophosphate inhibition of human Cathepsin A
| Autor: | Jaimee R. Compton, Mark A. Guelta, Patricia M. Legler, Kayla D. Bouknight, Steven P. Harvey, Ilja V. Khavrutskii, Kayla M. Jurkouich |
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| Rok vydání: | 2020 |
| Předmět: |
Models
Molecular Protein Conformation alpha-Helical 0301 basic medicine Sarin Isoflurophate Time Factors Soman Cathepsin A Gene Expression Cyclosarin Crystallography X-Ray GPI-Linked Proteins Biochemistry Cell Line Substrate Specificity 03 medical and health sciences chemistry.chemical_compound Organophosphorus Compounds 0302 clinical medicine Humans Protein Interaction Domains and Motifs Chemical Warfare Agents Cholinesterase Pharmacology Binding Sites biology Organophosphate Organothiophosphorus Compounds Acetylcholinesterase Recombinant Proteins Dissociation constant Kinetics HEK293 Cells 030104 developmental biology chemistry 030220 oncology & carcinogenesis biology.protein Protein Conformation beta-Strand Cholinesterase Inhibitors Protein Binding |
| Zdroj: | Biochemical Pharmacology. 177:113980 |
| ISSN: | 0006-2952 |
| DOI: | 10.1016/j.bcp.2020.113980 |
| Popis: | Human Cathepsin A (CatA) is a lysosomal serine carboxypeptidase of the renin-angiotensin system (RAS) and is structurally similar to acetylcholinesterase (AChE). CatA can remove the C-terminal amino acids of endothelin I, angiotensin I, Substance P, oxytocin, and bradykinin, and can deamidate neurokinin A. Proteomic studies identified CatA and its homologue, SCPEP1, as potential targets of organophosphates (OP). CatA could be stably inhibited by low µM to high nM concentrations of racemic sarin (GB), soman (GD), cyclosarin (GF), VX, and VR within minutes to hours at pH 7. Cyclosarin was the most potent with a kinetically measured dissociation constant (KI) of 2 µM followed by VR (KI = 2.8 µM). Bimolecular rate constants for inhibition by cyclosarin and VR were 1.3 × 103 M−1sec−1 and 1.2 × 103 M−1sec−1, respectively, and were approximately 3-orders of magnitude lower than those of human AChE indicating slower reactivity. Notably, both AChE and CatA bound diisopropylfluorophosphate (DFP) comparably and had KIDFP = 13 µM and 11 µM, respectively. At low pH, greater than 85% of the enzyme spontaneously reactivated after OP inhibition, conditions under which OP-adducts of cholinesterases irreversibly age. At pH 6.5 CatA remained stably inhibited by GB and GF and |
| Databáze: | OpenAIRE |
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