Number of polypeptide components in bacteriophage T2L contractile sheaths.

Isolated purified contractile tail sheaths of bacteriophage T2L were analyzed for their carboxyl terminal amino acids by carboxypeptidase treatment and hydrazinolysis. Glycine and serine were identified as the only two carboxyl end groups. Using corrections for the yields of these two amino acids upon hydrazinolysis, we calculated that there are 154 (+/-30) moles of C-terminal glycine and 130 (+/-45) moles of C-terminal serine per mole of sheath. It appears likely that sheaths contain two types of polypeptide chains in equal numbers, probably 144 of each. The relation of these two components to the mechanism of sheath contraction is discussed.