Halftime of hydrolysis event of glycogen (10^5 glycosidic bonds) at 25°C

Value 50 years
Organism Generic
Reference Wolfenden R, Snider MJ. The depth of chemical time and the power of enzymes as catalysts. Acc Chem Res. 2001 Dec34(12):938-45. p.940 table 1 Table - link PubMed ID11747411
Method Reaction rates were measured at series of elevated temperatures, following them to completion. The resulting Arrhenius plot, if linear, can then be extrapolated to 25 °C. In much of this work, reaction mixtures were sealed in quartz, heated over various intervals, and then opened for analysis by proton NMR. The vapor pressure of water does not change enough to affect reaction rates significantly, but aqueous samples tend to burst at temperatures above 250 °C (40 atm). Explosions are avoided by placing reaction tubes in water inside a steel bomb, equalizing pressure across the wall of each tube. PTFE vessels must be used for alkaline solutions which attack quartz.
Comments Value calculated by dividing halftime of spontaneous polysaccharide hydrolysis at 25°C, 4.7×10^6 years (BNID 105353) by number of glucose molecules in glycogen. Halftime of hydrolysis event of glycosidic bond in glycogen at 100°C is 12 hours. See table link.
Entered by Uri M
ID 105359