Principle of Method
This assay is a sandwich Enzyme Linked-Immunosorbent Assay (ELISA) for quantitative determination of human ACE2 in cell culture supernatants, serum, plasma and urine. A polyclonal antibody specific for human ACE2 has been precoated onto the 96-well microtiter plate. Standards (STD) and samples are pipetted into the wells for binding to the coated antibody. After extensive washing to remove unbound compounds, ACE2 is recognized by the addition of a biotinylated monoclonal antibody specific for human ACE2 (DET). After removal of excess biotinylated antibody, streptavidin-peroxidase (STREP-HRP) is added. Following a final washing, peroxidase activity is quantified using the substrate 3,3’,5,5’-tetramethylbenzidine (TMB). The intensity of the color reaction is measured at 450nm after acidification and is directly proportional to the concentration of ACE2 in the samples.
Human ACE2 gene, localized in X chromosome, encodes for a 805 amino acid protein with an N-terminal signal sequence, a metalloprotease zinc binding site (HEMGH) and a hydrophobic region near the C-terminus acting as a membrane anchor (transmembrane domain). Angiotensin-converting enzyme 2 (ACE2) is a type I transmembrane metallocarboxypeptidase within the renin-angiotensin system (RAS), which plays a key role in blood pressure regulation, fluid and electrolyte balance, thirst, cardiac/renal function and growth (1). ACE2 is expressed on the cell surface of type 2 alveolar epithelial cells in the lungs as well as on cells in many other tissues (2). ACE2 shares approximately 60% homology with ACE, the other key enzyme of the RAS system (3).
ACE2 converts angiotensin II (Ang II) into Ang (1-7), which acts on the Mas receptor and plays a role in cardiovascular disease to lower blood pressure through vasodilation and by promoting kidney sodium and water excretion, but also to lower inflammation (4). The effects of ACE2 directly oppose those induced by ACE-Ang II signaling, whereby ACE converts Ang I into Ang II, which increases blood pressure by inducing vasoconstriction, increasing kidney reabsorption of sodium and water and promoting inflammation.
ACE2 has been identified as a key receptor on target cells for SARS-CoV infections in 2002 (5). ACE2 functions as the entry receptor of the new SARS-CoV-2 coronavirus which is the cause of the new disease COVID-19. Strong binding of the spike protein of SARS-CoV-2 to ACE2, along with proteolytic cleavage of ACE2 by transmembrane serine protease 2 (TMPRSS2), facilitates entry of the virus into cells, viral replication and cell-to-cell transmission.
ACE2 can undergo an ADAM17 (a disintegrin and metalloproteinase 17)-mediated “shedding” from endothelial cells, resulting in the release of the ectodomain into the circulation (6). This soluble form may act as a competitive interceptor of SARS-CoV-2 and other coronaviruses by preventing binding of the viral particle to the surface-bound, full-length ACE2 (7). Soluble ACE2 might also be used as biomarker of hypertension and cardiovascular diseases (6).
Sandwich type ELISA
Angiotensin-converting enzyme 2, ACE2, hACE2, ACE-related carboxypeptidase, Angiotensin-converting enzyme homolog, ACEH, Metalloprotease MPROT15
Serum, Plasma-EDTA, Plasma-Heparin, Plasma-Citrate, Urine, Cell culture supernatant
Serum and Plasma : 50 µL (actual amount of sample loaded in well after dilution); Urine: 25 µL (actual amount of sample loaded in well after dilution)
Calibration Range: 0.0625 - 4.0 ng/ml
Limit of Detection
Intra-assay (Within-Run) C.V.
Inter-assay (Run-to-Run) C.V.
Want to learn more about ACE2? We have compiled the links below which contain information that you may find interesting:
- UniProt Knowledgebase: UniProtKB - Q9BYF1 (ACE2_HUMAN): Angiotensin-converting enzyme 2
- Scialo et al. "ACE2: The Major Cell Entry Receptor for SARS-CoV-2." Lung vol. 198(6), 867-877. Dec. 2020. doi: 10.1007/s00408-020-00408-4
References to Summary
- Intrarenal renin-angiotensin system in regulation of glomerular function: L.G. Navar; Curr. Opin. Nephrol. Hypertens. 23, 38 (2014)
- Tissue distribution of ACE2 protein, the functional receptor for SARS coronavirus. A first step in understanding SARS pathogenesis: I. Hamming, et al.; J. Pathol. 203, 63 (2004)
- A human homolog of angiotensin-converting enzyme: cloning and functional expression as a captopril-insensitive carboxypeptidase: S.R. Tipnis, et al.; J. Biol. Chem. 275, 33238 (2000)
- Angiotensin-converting enzyme 2-a new cardiac regulator: M. Boehm, et al.; New Eng. J. Med. 347, 1795 (2002)
- SARS-CoV-2 Cell Entry Depends on ACE2 and TMPRSS2 and Is Blocked by a Clinically Proven Protease Inhibitor: M. Hoffmann, et al.; Cell 181, 271 (2020)
- Circulating ACE2 in Cardiovascular and Kidney Diseases: L. Anguiano, et al., Curr. Med. Chem. 24, 3231 (2017)
- Inhibition of SARS-CoV-2 Infections in Engineered Human Tissues Using Clinical-Grade Soluble Human ACE2: V. Monteil, et al., Cell 181, 905 (2020)