Chelators in the lab: EDTA & EGTA biochemistry скачать в хорошем качестве

Chelators in the lab: EDTA & EGTA biochemistry

Metals have huge electron clouds - the places where electrons whizz around their atomic nuclei containing the positive protons reigning them in. When metals bond to other metals in metallic bonds, they kinda just merge some of their clouds into a vast, communal electron sea. And when electrons move throughout the sea you have electric current, which is why metals are good electrical conductors. But when metals bond to nonmetals, they often do so as COORDINATE COVALENT BONDS - these bonds form when one atom shares 2 electrons with a metal ion in the middle (in normal covalent bonds each atom shares one) - we call the result a COMPLEX and you can learn more about them here: https://bit.ly/2BDBml0 In order to complex with a metal, an atom has to have a lone pair of electrons they can share - like nitrogen or oxygen. If a molecule has more than one atom with a pair to spare, they can “bite down” on the metal in multiple places, hence POLYDENTATE. We call such multiple-toothed-biters CHELATORS A couple common chelators we use in the lab are EDTA and EGTA. We use EDTA more commonly but EGTA comes in handy when you really need to chelate calcium (and/or don’t want to strongly chelate magnesium). EGTA has a longer backbone that makes it hard to tightly grip magnesium so it has a much higher preference for Ca2+ compared to Mg2+. Here are some resources if you want to learn more: Chelation chemistry: General concepts of the chemistry of chelation, Dow Inc: https://www.dow.com/content/dam/dcc/d... Tsien R. Y. (1980). New calcium indicators and buffers with high selectivity against magnesium and protons: design, synthesis, and properties of prototype structures. Biochemistry, 19(11), 2396–2404. https://doi.org/10.1021/bi00552a018 free version: http://www.tsienlab.ucsd.edu/Publicat... Metal Chelates Table of Stability Constants: https://www.dojindo.eu.com/images/Pro... Preparation of 0.5 M EDTA Stock Solution from Anhydrous EDTA Free Acid, Laboratory Notes: https://www.laboratorynotes.com/prepa...   more about all sorts of things: #365DaysOfScience All (with topics listed) 👉 http://bit.ly/2OllAB0 or search blog: http://thebumblingbiochemist.com                                                          #scicomm #biochemistry #molecularbiology #biology #sciencelife #science #realtimechem