STRUCTURAL AND CHEMICAL ARCHITECTURE OF HOST CELLS 23 



reaction are as yet poorly characterized and it cannot yet be stated that the 

 T-even viruses act catalytically in lowering the energy of activation of a 

 specific reaction, it appears to be only a matter of time before the precise 

 character of the hydrolytic activity of these viruses is defined. 



CHOH 



CHj HCNHCGCHj 

 HOOC I I 



C CH 

 D-glucopyranose- (4-^ I) -/3-D -galactosyl q^ ^O^ I 



/ HC-O-COCHj 



viral enzyme I 

 or RDE HCOH 



I 

 CH,OH 



(a) Neuramin- lactose 



CH,OH 

 I CHOH 



, P 9\ C^ HCNHCOCH, 



[/ '\iHOOC I I 



protein-l C C-^^^l qj ^O | 



' / HC-O-COCH3 



viral enzyme ' 

 or RDE "Y°" 

 CH2OH 



(b) Prosthetic group of the mucoprotein of bovine 

 submaxillary gland 



Fig. 2. The mode of action of the neuraminidases of influenza virus and RDE 

 (Gottschalk, 19o7a,b). 



A somewhat more satisfying chemical position, summarized by Gottschalk 

 (1957a), has been attained with respect to the hydrolytic activity of influenza 

 virus. The virus appears to contain a glycosidase which has not yet been 

 found in any of the cells that support multiplication of influenza virus. A 

 similar soluble glycosidase is produced in cultures of Vibrio cJwlerae and has 

 been called the receptor-destroying enzyme (RDE). The substrate for viral 

 glucosidase and RDE is present at the surface of appropriate erythrocytes 

 and apparently on susceptible ceUs of mouse and ferret lung. Pre-treatment 

 of these ceUs with RDE hinders their subsequent infection by influenza virus. 

 In addition, many animal products, e.g., mucins, urinary mucoprotein, etc., 

 possess the ability of interfering with the ability of the virus to agglutinate 

 red cells and may be degraded by virus and RDE. It appears that both the 

 cellular receptors and soluble products contain a common grouping capable 

 of reactmg with the glycosidase. 



When the virus is incubated with a purified mucoprotein isolated from 

 human urine, an acetyl neuraminic acid (siahc acid) is released (see Fig. 2). 



