Ovomucoid, carbohydrate residue

It was found possible to saponify ovomucoid with sodium hydroxide and to methylate simultaneously with methyl Bulfate, the carbohydrate residue thereby forming an N-acetyl methyl derivative.14 Hydrolysis of this material yielded N-acetyl-3,4,6-trimethyl-D-glucosamine (7 moles) (LIVJ, D-mannopyranose (2 moles) (LV), 3,4,6-trimethyl-D-mannopy-ranose (1 mole) (LVI), and tetramethyl-D-galactopyranose (1 mole) (LVII). 

While it is impossible to make any precise statement regarding the structure of this blood group A polysaccharide until our present investigations are more advanced, it does seem possible that the structure of the alkali-stable carbohydrate residue is of a ramified type, bearing some general relationship to that deduced for ovomucoid, which, however, is much less resistant to hydrolysis than is this blood group A polysaccharide. 

Pspsin (EC 3.4.23.1) a protease in the stomach of all vertebrates with the exception of stomachless fish (e.g. carp). Purified P. shows maximal activity at pH 1-2, but in the stomach the optimal pH is 2-4. Above pH 6, P. is inactivated by denaturation. It preferentially catalyses hydrolysis of peptide bonds between two hydrophobic amino acids (Phe-Leu, Phe-Phe, Phe-TyrT With the exception of protamines, keratin, mucin, ovomucoid and other carbohydrate-rich proteins, most proteins are attacked by P. The products of P. action are peptone, i. e. mixtures of peptides in the M range 300-3,000. P. is a highly acidic (pi 1), single chain phosphoprotein (327 amino acid residues of known primary sequence, M, 34,500), which is released from its zymogen (pepsinogen, 42,500) by autocatalysis in the presence of hydrochloric acid. 

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