Trypsin supported on MCM-41 is demonstrated as a stable catalyst for the transesterfication of N-acetyl-L-tyrosine ethyl ester with propan-1-ol. An enzyme loading of 5 micromoles of trypsin per gram of silicate was readily achieved. The ultimate enzyme loading was shown to depend strongly on enzyme purity. The adsorbed enzyme exhibited the same turnover frequency for the transesterification reaction as native trypsin, the catalyst could be reused without loss of activity following separation by centrifuging and the enzyme did not leach during testing.