Substrate Specificity of Neurotropic Influenza Virus Neuraminidases.

FIG. 1. Effect of incr-easing substrate concentrations upon the magnitude of reaction with three influenza virus enzymes. Substrate in 0.5 si phosphate-buffered saline (PBS), pH 6 as indicated, and PBS to a total of 0.25 ml (human ac-GP, 4 mg/ ml; ovo, 40 mg/nil; PSM, 30 mg/ml), 0.05 ml of enzyme. Enzymes for these studies were virus concentrates prepared from infected chorioallantoic fluid by centrifugation. Sialic acid was quantitated by the thiobarbituric acid method (Warren, J. Biol. Chem. 234:1971, 1959).