Allosteric inhibition of the water-soluble C-terminal fragment of Sendai virus neuraminidase
Dallocchio, F.; Bellini, T.; Martuscelli, G.; Baiocchi, M.; Tomasi, M.
Biochemistry International 25(4): 663-668
1991
ISSN/ISBN: 0158-5231 PMID: 1726131 Document Number: 376006
Trypsin solubilized hemagglutinin-neuraminidase of Sendai virus (cHN) displays michaelian kinetics, with native fetuin as substrate, at 37 degrees C. Vmax and Km values are only marginally altered, as compared to intact viral neuraminidase. At lower temperatures, cHN follows non-michaelian kinetics, with marked substrate inhibition at 4 degrees C. With denaturated fetuin, michaelian kinetics are observed in all conditions, while asialo fetuin was an uncompetitive inhibitor of cHN, with native fetuin or sialyl lactose as substrates. These results can be explained assuming that the protein moiety of fetuin acts as an allosteric inhibitor of cHN.