METCALF 



was reported recently by Noll, Aeyagi and Orlando (1961) and Mayren 

 et al. (1961). 



When ovomucin was used in place of neuraminmucoid, different 

 results were obtained, Enzymic destruction of substrate occurred 

 rapidly at all temperatures when measured by the IR method. Only 

 slight differences in the rate of of substrate hydrolysis and the time 

 required to reach the same endpoint could be shown. The results of 

 the TBA analyses showed the rate of enzymic attack on ovomucin to 

 be similar to the values found with neuraminmucoid. The efficiency 

 of the hydrolysis was considerably improved, however, and indicated 

 a more labile, more available enzyme-vulnerable structure (Fig. 3), 



The inhibitory titer of the two inhibitor preparations for indicator 

 virus varied markedly. Based on the bound neuraminic acid content, 

 ovomucin containing 3 x 10"'^ micrograms was inhibitory. Using the 

 same basis neuraminmucoid containing 7 x 10"^ micrograms was 

 inhibitory. The ovomucin inhibitory value of 3 x lO"'^ micrograms 

 agreed well with the value 4-8x10"'^ micrograms reported by Gott- 

 schalk and Lind (1949) for their preparation of ovomucin, Tamm and 

 Horsfall (1952) reported an inhibitor titer of 3 x 10" '^ for urinary 

 mucoprotein at equilibrium with influenza virus. There are no 

 values published for neuraminmucoid. 



Ovomucin contained 0,18 per cent total protein, determined by the 

 Biuret test ; 0.0 5 per cent hexose, deter mined by the modified Orcinol 

 method of Rosevear and Smith (1961); and 1.5 micrograms per ml of 

 total bound neuraminic acid. The neuraminmucoid preparation con- 

 tained 4.86 per cent total solids, 1.68 per cent total protein, 0.97 

 per centhexose,andllmicrogramsper mlof bound neuraminic acid. 



For the purposes of the study, the results showed that neuramini- 

 dase continued to attack substrate at 20° C, but with decreased 

 efficiency. Both the rate and extent of enzyme action were affected. 

 The marked difference in the values obtained with ovomucin and 

 neuraminmucoid substrates was interpreted as the result of chem- 

 ically different compounds possessing enzyme- labile structures of 

 varying accessibility and possibly different chemical composition. 



348 



