Enzymological heterogeneity of influenza B virus neuraminidase demonstrated by the fluorometric assay method.
The neuraminidase activity of 26 strains of influenza B virus isolated from all over the world was investigated colorimetrically, using fetuin as a substrate, and fluorometrically, using 4-methylumbelliferyl(4-MU)-N-Ac-alpha-D-neuraminide as a substrate, with special reference to enzymological heterogeneity. The activity of influenza A viral neuraminidases and of a commercially available pure viral one was strongly inactivated by either ethylenediaminetetraacetic acid or glycoletherdiaminetetraacetic acid, when measured by the fluorometric assay method, whereas that of influenza B ones was not at all. However, the viral neuraminidases of both influenza A and B viruses were found to be calcium ion-dependent by the colorimetric assay method. A difference in the catalytic rate between the two assay methods was observed with influenza B viral neuraminidase to a much greater extent as compared with that of influenza A. A difference in substrate specificity of these enzymes was demonstrated to be due to a difference in the degree of competitive inhibition by N-acetylneuraminic acid. These findings strongly suggest that enzymological heterogeneity in influenza B viral neuraminidase may be attributed to delicate structural differences, between the enzymes of influenza A and B viruses demonstratable only by the fluorometric neuraminidase assay method using 4-MU-N-Ac-alpha-D-neuraminide as a substrate.
Kiyotani
K
K
Takei
N
N
Matsuo
Y
Y
D003016:Clostridium perfringens / Q000187:drug effects / Q000201:enzymology; D003124:Colorimetry; D004305:Dose-Response Relationship, Drug; D004492:Edetic Acid / Q000494:pharmacology; D004533:Egtazic Acid / Q000494:pharmacology; D009980:Influenza A virus / Q000187:drug effects / Q000201:enzymology; D009981:Influenza B virus / Q000187:drug effects / Q000201:enzymology*; D009439:Neuraminidase / Q000032:analysis* / Q000037:antagonists & inhibitors; D013045:Species Specificity; D013050:Spectrometry, Fluorescence; D010948:Viral Plaque Assay
D004533:Egtazic Acid; D004492:Edetic Acid; D009439:Neuraminidase