CHEMISTRY OF VIRUS RECEPTORS 55 



conditions of the chemical synthesis and fragmentation of NANA epimer- 

 ization had taken place. The OH- group at C 4 of NANA is in cis-position 

 to the acetamido group (Kuhn and Brossmer, 1957). The results 

 of periodate oxidation would indicate that NANA in aqueous solution 



CHOH CHOH 



H 2 C^ W> hh:NHAc H 2 C X >CNH a 



HO J | ^_9> HO J I 



^CW XH alkali ^C CH 



HOOC^ X | HOOC^ X X | 



N-ACETYL- ^ H ° H ) 2 NEURAMINIC (<f HOH )i 



NEURAMINIC ' nu ACID 



ACID ~ CH2 ° H o 



o 



i CH,OH 

 to 2 



I 



J 



\k 



HC=0 HCH -2H a O H f jf H f HO 



I + • alkali > " l H + (CHOH) 2 



H ^NH 2 0^ C ^COOH HC \ ^ C - C °2 H | 



(choh) 3 pyruvic 



N H CHOH 



ACID PYRROL E-2-CARB OX YLIC TETROSE 



CH 2 OH ACID 



D-GLUCOSAMINE 



Fig. 1. Degradation of N-acetylneuraniinic acid to pyrroIe-2-carboxylic acid. 



exists predominantly in the pyranose form and that ON-diacetylneur- 

 aminic acid has the O-acetyl group attached to C 7 (Blix et al., 1956 ; 

 Klenk et al, 1956). 



Sialic acid, the group name for ON-diacetylneuraminic acid, iV-acetyl- 

 neuraminic acid, iV-glycolylneuraminic acid, and other acylated neuraminic 

 acids (for nomenclature see Blix, et al, 1957), is an intrinsic component 

 of all hemagglutinin inhibitory mucoproteins (Odin, 1952, 1957; Gottschalk, 

 1955a, 1956a; Werner and Blix, 1956). NANA has been obtained crystalline 

 from UM, serum mucoprotein, from the inhibitory mucoproteins present in 

 meconium, ovarian cyst fluids, human cervical mucus, human milk, and from 

 ovomucin; diacetymeuraminic acid from BSM (Klenk et al., 1955; Bohm et 

 al., 1957; Zilliken et al., 1955; Odin, 1955; Blix, 1936). As product of enzymatic 

 cleavage (virus or vibrio enzyme) NANA has been obtained with BSM, UM, 

 and serum and meconium mucoproteins as substrates (Faillard, 1957; Bohm 

 et al., 1957; Zilliken et al., 1957). Moreover, Klenk and Lempfrid (1957) were 

 able to split off NANA from human erythrocytes with RDE and to crystallize 



