The tail fibre of bacteriophage T4 is sensitive to proteases at elevated temperatures

Bacteriophage T4 wild-type is not sensitive to heating at 60 degrees C. Trypsin at this temperature quickly inactivates the bacteriophage, with first-order kinetics for about the first 60 min. The half-inactivation period is around 15 min. The characteristics of this inactivation reaction have been studied. Inactivation of T4 particles is paralleled by a loss in ability to adsorb to bacteria. SDS-PAGE reveals a 'clipping' of gp 37, the protein of the distal part of the long tail fibres, during the inactivation reaction. gp 37 is the only protein to be modified under these conditions. Mutants have been isolated which resist this modification, they map in gene 37.