Effect of some anthracycline antibiotics on the neuraminidase activity of Sendai virus and its isolated glycoproteins.

Anthracycline antibiotics violamycin BI (VBI) and adriamycin (Adr) strongly inhibited the neuraminidase (NA) activity of Sendai virus and of its isolated glycoproteins, occurring either in solution or associated in liposome-like particles. NA did not exhibit the classical Michaelis-Menten kinetics: the plot of reaction velocity versus substrate concentration was sigmoidal, while Hill's plotting indicated that the enzyme has at least two binding sites for the substrate. The reaction kinetics obtained suggested that Sendai virus NA acts as an allosteric enzyme, when its material support, the HN is located on the virus surface. The inhibitory effect of the anthracycline antibiotics in question on the NA activity seemed to be similar to that of negative effectors.