Abstract
Thiaminase activity (thiamin : base 2-methyl-4-aminopyrimidine methyl transferase, EC 2.5.1.2) was detected in the silkworm, Bombyx mori. Extracts of the larvae and pupae of Bombyx mori exhibited thiaminase activity with an optimal temperature of 70°C and optimal pH value of 9.0. Bombyx thiaminase was a non-dialyzable protein with a molecular mass greater than approx. 10, 000 Da. This enzyme showed no activity towards any thiamin phosphate ester tested. Pyridoxine, several amino acids and some SH compounds were effective as a second substrate. It seems crucially important to inactivate thiaminase by heating when processing the larvae and pupae of Bombyx mori as a foodstuff.
