A study of the organic material of hen's-egg shell

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Abstract
Hen''s-egg-shell matrix, cuticle and membranes were prepared separately by decalcification of the shell with ethylenediaminetetraacetic acid. The matrix consists mainly of a protein -polysaccharide complex containing 11% of polysaccharide and at least 70% of protein. The matrix protein is characterized by the absence of hydroxyproline, the low concentration of aromatic and sulphur-containing amino acids and the presence of about twice as much dicarboxylic amino acids as basic amino acids. Chondroitin sulphates A and B are present in the matrix and comprise 35% of the total polysaccharide. Some galactosamine is present in a form other than chondroitin sulphate along with glucosamine, galactose, mannose and fucose. The concentration of galactose is greater than that of mannose, and fucose is present in trace amounts. The molar ratio hexosamine:neutral sugar is close to 1:1, but no information is available as to the form(s) in which they are combined. The membranes are mainly keratin with a small amount of polysaccharide containing hexosamine, galactose and probably mannose. Part of all of the polysaccharide may originate from the mammillary cores. Some 90% of the cuticle is protein, which is distinguished from the membrane and matrix proteins by its content of tyrosine, glycine lysine and cystine. Hexosamine is present together with galactose, mannose and fucose.