Reversible Chemical Modification of Protein by 2-Methoxy-5-nitrotropone

Publisher Website
Google Scholar
Abstract
1. 2-Methoxy-5-nitrotropone, a new reagent for reversible chemical modification of amino groups in protein, was studied with Taka-amylase A [EC 3.2.1.1] as the sample protein. 2. Treatment of Taka-amylase A with 2-methoxy-5-nitrotropone results in about 65% loss of the amylase activity and some activation of the maltosidase activity. Nitrotroponyl Taka-amylase A can be denitrotroponylated by hydrazine. The regenerated Taka-amylase A is not distinguishable from intact Taka-amylase A by DEAE-cellulose column chromatopraphy, enzyme activities, optical rotatory dispersion or susceptibility to bacterial proteinase. 3. The c-amino groups of lysine residues in Taka-amylase A may not be essential for the amylase activity and the decrease of the amylase activity of nitrotroponyl Taka-amylase A may be due to a steric hindrance by the nitrotroponyl residue combined with the amino group of a lysine residue situated close to the active site.