Melanoidin, which was obtained by the Maillard reaction between D-gluc
ose and glycine, was found to exert a potent inhibitory effect on the
activity of trypsin with BANA as a synthetic substrate. The concentrat
ion of melanoidin required to reduce the activity of trypsin by 50% wa
s less than 1 mu g/ml, similar to that of soybean trypsin inhibitor an
d leupeptin. On the other hand, chymotrypsin was not affected by melan
oidin. The specific interaction between melanoidin and trypsin is disc
ussed.