To Measure the Absorbance at 328nm by Ultraviolet-Visible Spectrophotometer - an Alternative Pathway to Measure the Activity of Acetylcholinesterase

Abstract

Acetylcholinesterase (AChE) is an important enzyme in mammalian nervous systems. The Ellman assay is usually used to measure AChE activity and calculate the inhibition rate by measure the absorbance at 412nm by UV-Vis spectrophotometer. However, an alternative absorbance at 329nm which assigned as S-S of 5,5'-dithio-bis-2-nitrobenzoic acid (DTNB) was found, and it negatively correlated with the absorbance at 412nm. Therefore, the absorbance at 329nm was also possible used to measure AChE activity and calculate the inhibition rate. In addition, the reaction time should be considered in the process to transfer the relationship of these two absorbance values, because Cu (II) would combine with 5'-mercapto-2'-nitrobenzoic acid (5-MNBA).