Human ASM (Acid Sphingomyelinase) ELISA Kit

The test principle applied in this kit is Sandwich enzyme immunoassay. The microtiter plate provided in this kit has been pre-coated with an antibody specific to Human ASM. Standards or samples are added to the appropriate microtiter plate wells then with a biotin-conjugated antibody specific to Human ASM. Next, Avidin conjugated to Horseradish Peroxidase (HRP) is added to each microplate well and incubated. After TMB substrate solution is added, only those wells that contain Human ASM, biotin-conjugated antibody and enzyme-conjugated Avidin will exhibit a change in color. The enzyme-substrate reaction is terminated by the addition of sulphuric acid solution and the color change is measured spectrophotometrically at a wavelength of 450nm ± 10nm. The concentration of Human ASM in the samples is then determined by comparing the OD of the samples to the standard curve. Protein Function: Converts sphingomyelin to ceramide (PubMed:12563314, PubMed:1840600, PubMed:18815062, PubMed:25339683, PubMed:25920558, PubMed:27659707, PubMed:33163980). Exists as two enzymatic forms that arise from alternative trafficking of a single protein precursor, one that is targeted to the endolysosomal compartment, whereas the other is released extracellularly (PubMed:20807762, PubMed:21098024, PubMed:9660788). However, in response to various forms of stress, lysosomal exocytosis may represent a major source of the secretory form (PubMed:12563314, PubMed:20530211, PubMed:20807762, PubMed:22573858, PubMed:9393854) , In the lysosomes, converts sphingomyelin to ceramide (PubMed:20807762, PubMed:21098024). Plays an important role in the export of cholesterol from the intraendolysosomal membranes (PubMed:25339683). Also has phospholipase C activities toward 1,2-diacylglycerolphosphocholine and 1,2-diacylglycerolphosphoglycerol (PubMed:25339683). Modulates stress-induced apoptosis through the production of ceramide (PubMed:8706124) , When secreted, modulates cell signaling with its ability to reorganize the plasma membrane by converting sphingomyelin to ceramide (PubMed:12563314, PubMed:17303575, PubMed:20807762). Secreted form is increased in response to stress and inflammatory mediators such as IL1B, IFNG or TNF as well as upon infection with bacteria and viruses (PubMed:12563314, PubMed:20807762, PubMed:9393854). Produces the release of ceramide in the outer leaflet of the plasma membrane playing a central role in host defense (PubMed:12563314, PubMed:20807762, PubMed:9393854). Ceramide reorganizes these rafts into larger signaling platforms that are required to internalize P.aeruginosa, induce apoptosis and regulate the cytokine response in infected cells (PubMed:12563314). In wounded cells, the lysosomal form is released extracellularly in the presence of Ca(2+) and promotes endocytosis and plasma membrane repair (PubMed:20530211) , This form is generated following cleavage by CASP7 in the extracellular milieu in response to bacterial infection (PubMed:21157428). It shows increased ability to convert sphingomyelin to ceramide and promotes plasma membrane repair (By similarity). Plasma membrane repair by ceramide counteracts the action of gasdermin-D (GSDMD) perforin (PRF1) pores that are formed in response to bacterial infection (By similarity) , (Microbial infection) Secretion is activated by bacteria such as P.aeruginosa, N.gonorrhoeae and others, this activation results in the release of ceramide in the outer leaflet of the plasma membrane which facilitates the infection , (Microbial infection) Secretion is activated by human coronaviruses SARS-CoV and SARS-CoV-2 as well as Zaire ebolavirus, this activation results in the release of ceramide in the outer leaflet of the plasma membrane which facilitates the infection , Lacks residues that bind the cofactor Zn(2+) and has no enzyme activity , Lacks residues that bind the cofactor Zn(2+) and has no enzyme activity [The Uniprot Consortium]