2023 Volume 54 Issue 1 Pages 69-81
In Japan, two types of glucagon products, which contain recombinant glucagon or synthetic glucagon as an active ingredient, have been approved and marketed. On June 7th, 2021, the Glucagon (Genetical Recombination) monograph was newly listed in the eighteenth edition of the Japanese Pharmacopoeia (JP). In the monograph, peptide mapping with α-chymotrypsin was set as the identification test; however, the specification of theα-chymotrypsin reagent is unclear because there is no information about the substrate used in the activity assay, the definition of the enzyme unit or the purity. Therefore, selecting anα-chymotrypsin reagent can be an issue when performing the identification test. In this study, we measured the chymotrypsin activity and residual trypsin activity of severalα-chymotrypsins, including the United States Pharmacopeia and the European Pharmacopoeia chymotrypsin reference standards and commercially availableα-chymotrypsin reagents, and conducted an identification test according to the JP glucagon monograph; theseα-chymotrypsins were used to evaluate the effect of differences in the activity of the chymotrypsin and residual trypsin on the test results. As a result, it was found that the current specification for chymotryptic activity of the JPα-chymotrypsin reagent may be higher than necessary to obtain the intended peptide map, and slight tryptic activity is required to generate the reference peptide peaks. Based on these findings, we discuss the appropriate specification of the JPα-chymotrypsin reagent.
