Does Low Fluorophore PKa = Low PH Sensitivity? - Microforum Home » What Does Low Pka Mean » Does Low Fluorophore PKa = Low PH Sensitivity? - Microforum Maybe your like What Does Low Resolution Mean What Does Lpl Stand For What Does Lt Tires Mean What Does Ltg Stand For What Does Ltm Stand For Does low fluorophore pKa = low pH sensitivity? Probes & Prep fluorescent-proteins LPUoO August 10, 2019, 8:56pm 1 Hi, Simple question : does low fluorophore pKa = low pH sensitivity ? Does for example a pKa of 4 mean that the fluorphore will be stable above pH 4 ? @talley Thanks a lot 1 Like talley August 10, 2019, 9:50pm 2 pKa is the pH at which fluorescence intensity drops to 50% of it’s maximal value… so yeah, a low pKa suggests the fluorophore is more acid-tolerant. Note though, that’s a bit of an oversimplification: it’s not a binary “on/off” above and below the pKa value. It’s a sigmoidal change, and the slope of that fluorescence-vs-pH curve (the Hill coefficient) also determines pH sensitivity. @joachimgoedhart may have more to say on the topic… he was on a recent paper that discussed this nicely… here’s an excerpt from that paper: … pH quenching curves can be described by a Hill fit that gives a pKa value and a Hill coefficient. The pH robustness can easily be misinterpreted by only looking at pKa values. However, FPs with a low pKa and a low Hill coefficient do not show a pH range in which the fluorescence remains constant and are still pH-sensitive. On the other hand, FPs with a low pKa and a high Hill coefficient are pH-insensitive as these FPs have a plateau at pH values above the pKa. Thus, pH-insensitive FPs are better identified based on these two parameters combined. In addition, pH sensitivity has always been described in vitro , neglecting the effect of cytolosic components on the pH quenching. How representative in vitro pH sensitivity is for the in vivo performance is unknown. Botman et al (2019). Scientific Reports 3 Likes joachimgoedhart August 18, 2019, 8:34pm 3 For fluorescent proteins it is usually true that a low pKa means high tolerance to acid. Note that FPs can have multiple pKa’s and that (as mentioned by Talley) and that the Hill coefficient may be relevant for the response to pH. Therefore, it’s best to check the fluorescence in response to a range of pH values (these data are often unavailable). 4 Likes Related topics Topic Replies Views Activity Mounting media and fluorophore compatibility 2 1677 August 4, 2020 Welcome to the Microtutor discussion forum Microtutor 2 219 October 12, 2024 Water Dipping Objective in pH 10-12 environment. A hazard for the Objective? Hardware 1 535 May 27, 2020 Sharp/bright fluorescent images vs pale? 3 661 April 12, 2023 Plant FP - please offer advice on what FP to choose Probes & Prep fluorescent-proteins 4 741 October 1, 2019 Tag » What Does Low Pka Mean 8.3: PKa Values - Chemistry LibreTexts PKa Definition In Chemistry - ThoughtCo What Is PKa? - ChemTalk PKa And Its Relationship With How Acidic Something Is - CHEMISTRY ... PKa And Dissociation Equilibrium - Shimadzu PKa - Definition, Calculation Of Pka, List Of PKa Values, Relationship ... PKa Meaning - An Introduction To Acid Dissociation Constant ... - Byju's [PDF] About PKa's What Does A High PKa Indicate? - Quora Posts Tagged "pKa" What Is The PKa Range For Weak Acids And Bases? Acid Base - How Do You Explain PKa To Non-professional? PKa & PH Values| Functional Groups, Acidity & Base Structures The PKa Table Is Your Friend - Master Organic Chemistry