The disulphide bonds of an Asian influenza virus neuraminidase

The arrangement of the disulphide bonds in the pronase-released neuraminidase heads of the Asian influenza virus A/Tokyo/3/67 have been examined by cyanogen bromide fragmentation, enzymic digestion and diagonal peptide mapping. There are 9 intrachain disulphide bridges and one interchain bridge which links pairs of monomers at the distal end of the stalk region of the neuraminidase tetramer. The disulphide bond arrangements of the remaining 3 half-cystine residues in the membrane-embedded stalk region of the neuraminidase were not examined.