抄録
Monochlorotrifluoro-p-benzoquinone (CFQ) was used for investigating the state of the amino groups of acid-stable α-amylase and acid-unstable α-amylase. About half of the total amino groups in both enzyme molecules were reacted with the reagent. The unreactive amino groups seemed to exist in a different state from the reactive ones. Both enzymes whose amino groups were modified by CFQ still maintained the α-phenylmaltosidase activity in spite of losing or decreasing the amylase activity. These facts suggest that the amino groups of both enzymes were not in the active site but the modification of them caused steric hindrance.
The pH-stability of the acid-unstable α-amylase whose one or two amino groups were modified with succinic anhydride or 2, 4, 6-trinitrobenzene-1-sulfonate (TNBS) increased on the acidic side and decreased on the alkaline side, but further modification of them led to decrease the stability on both sides.
