C. B. METZ 45 



Chemical studies have been restricted mainly to the fertilizins 

 from sea urchins. Sea urchin fertilizin (egg jelly or jelly coat 

 substance) can be prepared in rather pure form by brief extrac- 

 tion of washed eggs in acid solution ( see Tyler 1949, for method ) . 

 Such preparations give a single component on ultracentrifugal 

 and electrophoretic examination. These purified fertilizins have 

 been employed in the analytical studies. They are found to be 

 glycoproteins which, on hydrolysis, yield a number of amino 

 acids, one or a few monosaccharides and considerable sulfate. 

 The amino acid composition of several species has been examined. 

 In S. purpurattis chromatographic analyses (Tyler, 1948c, 1949, 

 1955 ) have revealed fifteen amino acid spots identified as glycine, 

 alanine, serine, threonine, valine, leucine, isoleucine, aspartic, 

 glutamic, arginine, lysine, phenylalanine, tyrosine, tryptophane, 

 and proline. In Echinus esculent us, Paracentrotus lividus, and 

 Strongylocentrotus droebachiensis nine (lysine, arginine, his- 

 tidine, valine, isoleucine, threonine, phenylalanine, tyrosine, and 

 proline) were demonstrated by microbiological assay (Vasseur, 

 1948, 1952a). Aspartic and glutamic acids were also found in 

 these fertilizins by chromatography (Vasseur, 1948). Thus a 

 considerable number of amino acids are present in sea urchin 

 fertilizin. The proportions of the amino acids showed little varia- 

 tion among the above three species studied by Vasseur. However, 

 Echinocardium cordatum fertilizin was low in lysine and valine. 



The monosaccharides found in hydrolyzates of several species 

 are listed in Table III. In contradistinction to the amino acids, the 

 number of different monosaccharides in any species is small. The 

 galactose of E. esculentus occurs mainly in the "unnatural" or 

 L-form (Vasseur, 1950). 



Sulfate has been found to the extent of about 25% in most 

 fertilizins (e.g., S. droebachiensis, Vasseur, 1947; S. purpuratus, 

 Tyler, 1949). Brissopsis hjrifera fertilizin, on the other hand, is low 

 in sulfate (about 4%). This, correlated with the fact that B. hjri- 

 fera fertilizin does not agglutinate sperm (Vasseur, 1952a; Vas- 

 seur and Carlsen, 1948'; Vasseur and Hagstrom, 1946), suggests 

 that sulfate gi^oups are essential for helping endow the molecule 

 with agglutinative properties (see below). 



