Chemical element isotopes: specifically the elements without any stable isotopes are technetium (atomic number 43), promethium (atomic number 61), and all observed elements with atomic numbers greater than 82. Of the 80 elements with at least one stable isotope, 26 have only one single stable isotope. The mean number of stable isotopes for the 80 stable elements is 3.1 stable isotopes per element. The largest number of stable isotopes that occur for a single element is 10 (for tin, element 50). The mass number of an element, "A", is the number of nucleons (protons and neutrons) in the atomic nucleus. Different isotopes
Sn-glycerol-1-phosphate dehydrogenase Sn-glycerol-1-phosphate dehydrogenase In enzymology, a "sn"-glycerol-1-phosphate dehydrogenase () is an enzyme that catalyzes the chemical reaction The 3 substrates of this enzyme are sn-glycerol 1-phosphate, NAD, and NADP, whereas its 4 products are glycerone phosphate, NADH, NADPH, and H. This enzyme belongs to the family of oxidoreductases, specifically those acting on the CH-OH group of donor with NAD or NADP as acceptor. The systematic name of this enzyme class is sn-glycerol-1-phosphate:NAD(P) 2-oxidoreductase. This enzyme is also called glycerol-1-phosphate dehydrogenase [NAD(P)]. G-1-P dehydrogenase is responsible for the formation of "sn"-glycerol 1-phosphate, the backbone of the membrane phospholipids of Archaea. The gene