five viruses of this group , differing in tryptophan content of their coat proteins , were used : v-tm virus ( 3 tryptophan residues per protein subunit ) , strains hr and u2 ( 2 tryptophan residues per subunit ) , dolihos enation mosaic virus and cucumber virus 4 ( 1 tryptophan residue per subunit ) .
C1136102
coat proteins
C0042776
virus