Human HTN3 (Histatin 3) 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 HTN3. Standards or samples are added to the appropriate microtiter plate wells then with a biotin-conjugated antibody specific to Human HTN3. 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 HTN3, 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 HTN3 in the samples is then determined by comparing the OD of the samples to the standard curve. Protein Function: Histatins are cationic and histidine-rich peptides mainly found in the saliva of higher primates (PubMed:3286634). They are considered to be major precursors of the protective proteinaceous structure on tooth surfaces (enamel pellicle). Hsts can be divided into two major groups according to their biological functions: antimicrobial Hsts (e.g. Hst 5/HTN3) and cell-activating Hsts (e.g. Hst 1/HTN1, Hst 2/HTN1 and Hst 3/HTN3) (PubMed:32225006) , Histatin 3 (Hst 3) is mostly involved in cell migration and wound healing in the oral cavity (PubMed:18650243). Also stimulates cell proliferation after binding to heat shock protein HSC70, which enhances HSC70-CDKN1B complex formation and subsequent ubiquitination during G1/S transition (PubMed:26775844). Also displays antifungal activity against pathogenic yeast Candida albicans, however with less effectiveness than Hst 5 (PubMed:11083804, PubMed:3286634) , Histatin 5 (Hst 5), a fragment of Hst 3, is the major histatin exhibiting antifungal and antibacterial activities (PubMed:10066791, PubMed:11083804, PubMed:11179305, PubMed:11717389, PubMed:12939362, PubMed:15485849, PubMed:2372245, PubMed:8945538). It is effective against pathogenic yeast C.albicans, C.neoformans, C.glabrata and S.cerevisiae as well as ESKAPE bacterial pathogens (PubMed:18974864, PubMed:23613860, PubMed:2372245, PubMed:28261570, PubMed:8945538). Secreted Hst 5 mediates a multi-step intracellular mechanism of action against the pathogen. Depending on peptide concentration and pathogen, uptake across the membrane can occur through transporters, direct interaction with plasma membrane and/or receptor-mediated endocytosis (PubMed:18974864, PubMed:20487276, PubMed:28261570). Binds C.albicans cell wall proteins SSA1 and SSA2 and glycans in an energy-independent manner, then is taken up by the cells through fungal polyamine transporters DUR3 and DUR31 in an energy-dependent manner (PubMed:12761219, PubMed:20487276, PubMed:22033918, PubMed:23613860). Internalized Hst5 is then targeted to the energized mitochondrion to induce reactive oxygen species (ROS) formation and subsequent release of intracellular non-lytic ATP which ultimately leads to fungal cell death (PubMed:10066791, PubMed:11083804, PubMed:11717389). In addition, inhibits C.albicans TRK1 potassium-transporter which causes exudation of intracellular K(+), generating an osmotic imbalance leading to delayed membrane lysis and cell death (PubMed:15485849). Also acts as a potent inhibitor of bacterial proteases such as Lys-gingipain and Arg-gingipain (rgpB) from P.gingivalis as well as human metalloproteases MMP2 and MMP9 (PubMed:11179305). The binding of metals such as zinc, copper or nickel with Hst 5 results in the protection of the enamel and antimicrobial activities such as the inhibition of microbial growth by decreasing the metal concentration, the formation of ROS commonly associated with redox-active metals, the induction of membrane disruption mediated by zinc binding (PubMed:19846304, PubMed:28261570, PubMed:28763199, PubMed:32751915). Also involved in coating oral surfaces in the form of a salivary film which reduces colonization by C.albicans on epithelial cell surfaces (PubMed:26379655). Secreted Hst 5 can also internalize mammalian epithelial cells and target the mitochondria although it does not exert cytotoxic effects in these cells (PubMed:32225006). In contrast with Hst 3, not able to promote wound healing in mammalian host cells (PubMed:18650243) [The Uniprot Consortium]