title: The acid and enzymic hydrolysis of O-acetylated sialic acid residues from rabbit Tamm-Horsfall glycoprotein.
abstract: Rabbit Tamm-Horsfall glycoprotein and bovine submaxillary glycoprotein were both found to contain sialic acid residues which are released at a slow rate by the standard conditions of acid hydrolysis. These residues are also resistant to neuraminidases from Vibrio cholerae and Clostridium perfringens. This behaviour was attributed to the presence of O-acetylated sialic acid, since the removal of O-acetyl groups by mild alkaline treatment normalized the subsequent release of sialic acid from rabbit Tamm-Horsfall glycoprotein by acid and by enzymic hydrolysis. Determination of the O-acetyl residues in rabbit Tamm-Horsfall glycoprotein indicated that on average two hydroxyl groups of sialic acid are O-acetylated, and these were located on the polyhydroxy side-chain of sialic acid or on C-4 and C-8. These findings confirm the assumption that certain O-acetylated forms of sialic acid are not substrates for bacterial neuraminidases. Several explanations have been suggested to explain the effect of O-acetylation of the side-chain on the rate of acidcatalysed hydrolysis of sialic acid residues.
mesh_terms: D000107:Acetylation; D000818:Animals; D002417:Cattle; D002854:Chromatography, Paper; D003016:Clostridium perfringens / Q000201:enzymology; D004952:Esters / Q000032:analysis; D005557:Formaldehyde; D006023:Glycoproteins / Q000032:analysis* / Q000652:urine; D006868:Hydrolysis; D009438:Neuraminic Acids / Q000032:analysis*; D009439:Neuraminidase; D010504:Periodic Acid; D011817:Rabbits; D012972:Sodium Hydroxide; D013363:Submandibular Gland / Q000032:analysis; D013464:Sulfuric Acids; D014733:Vibrio / Q000201:enzymology
chemical_list: D004952:Esters; D006023:Glycoproteins; D009438:Neuraminic Acids; D013464:Sulfuric Acids; D010504:Periodic Acid; D005557:Formaldehyde; D012972:Sodium Hydroxide; D009439:Neuraminidase