The Activation of the Bacterial Virus T4 by l -Tryptophan

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Abstract
Expts. were performed in which samples of the bacterial virus T4 were exposed to a cofactor for adsorption, l-tryptophan, under various conditions. The samples were then mixed with suspensions of the host, Escherichia coli B, under identical conditions. The fractions of virus adsorbed varied with the conditions under which the virus had been exposed to its cofactor. The percentage activation varied with the following factors: (a) with tryptophan concn., it was negligible at 0.1 [gamma] per ml and rose sharply to high values at 2 [gamma] per ml; (b) with temp., it was maximum at 35 C and fell to low values at 0 C and 60 C; (c) with pH, it was maximum near pH 8; and (d) with the length of exposure (equilibrium with 2 [gamma] per ml was practically complete in 2 min. at 26 C). When incubated with tryptophan and then diluted in synthetic medium, the virus rapidly lost its ability to be adsorbed on its host. Upon re-exposure to an adequate concn. of a cofactor, it regained its ability to be adsorbed. It is concluded that the cofactor for adsorption, l-tryptophan, activated the bacterial virus T4 in a reversible manner. Possible functions of virus cofactors in the adsorption mechanism are discussed.
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