Influenza virus haemagglutinin: estimation of tryptophan and tyrosine content and localization of tryptophan residues -- Kharitonenkov et al. 50 (2): 419 -- Journal of General Virology

The tryptophan and tyrosine content of the bromelain-released subtype H3 haemagglutinin (H3 BHA) of influenza virus were measured by u.v. absorption and fluorescence techniques. The values obtained (8 and 18 residuces, respectively) are in close agreement with those derived from amino acid analysis. Essentially all of th tryptophan residues are demonstrated to be localized on the surface of the BHA molecule.