A. Lehninger
1957
Citations
0
Influential Citations
18
Citations
Journal
Methods in Enzymology
Abstract
Publisher Summary There are two types of such preparations of DPNH which have gained some use: the disodium salt and the barium salt. In both cases, the diphosphopyridine nucleotide (DPN) is reduced chemically with hydrosulfite. In the former procedure, the disodium salt is isolated subsequent to the removal of sodium sulfite and sodium sulfate formed from the hydrosulfite by fractional crystallization from the aqueous solution at very low temperatures. From the analytical and spectrophotometric data presented, it appears permissible to conclude that the preparation was about 92% pure and that about half of the impurity was BaCO 3 . It is possible that the rest may be moisture not removed at 60 ° but labile at 100 °. Such preparations of DPNH were stored in the cold over calcium chloride. Preparations held in a desiccator for a year at room temperature showed a decline of the 340 mg: 260 mμ ratio to about 0.26 and a decline of enzymatic assay values to about 70 % purity.