title: Isolation and partial characterization of a porcine parotid hormone that stimulates dentinal fluid transport.
abstract: A parotid hormone (PH-A beta) has been isolated and purified from porcine parotid glands. The biological effect of the hormone is the stimulation of a dentinal fluid transport (DFT) in molar teeth of rats. The method for purifying the PH-A beta includes: extraction at pH 7 and 5, ultrafiltration through Amicon membranes, ion exchange chromatography on carboxymethyl cellulose, gel filtration on Sephadex G-50, and preparative electrophoresis in polyacrylamide gel. The PH-A beta is characterized as a glycoprotein having a molecular weight of 8100 and containing 2% hexose. The amino acid composition suggests a molecule rich in glycine (46%) and proline (27.7%). Alanine, glutamic acid, arginine, serine, aspartic acid, leucine, and lysine account for the remaining 26% of the residues. The isoelectric point is pH 7.50. The partial N-terminal amino acid sequence was determined to be: NH2-Ala-Pro-Pro-Gly-Ala-Arg-Pro-Pro-Pro-Gly-Pro-Pro-Pro-Pro-Pro-Pro-(Glu)-(Pro)-?-(Pro)-(Pro)-Arg-(Pro)-(Pro)-(Pro)-Gly-(Gly)-(Gly). A 5.5 X 10(7)-fold increase in DFT activity has been achieved relative to the crude gland extract. As little as 9.7 pg PH-A beta are effective in stimulating DFT. The significance of the PH-A beta appears to be the maintenance of a functional DFT within teeth to allow the avascular dental tissues to meet their high metabolic requirements.
mesh_terms: D000595:Amino Acid Sequence; D000596:Amino Acids / Q000032:analysis; D000818:Animals; D001681:Biological Assay; D002241:Carbohydrates / Q000032:analysis; D003804:Dentin / Q000187:drug effects / Q000378:metabolism*; D004591:Electrophoresis, Polyacrylamide Gel; D008297:Male; D008970:Molecular Weight; D051381:Rats; D012471:Salivary Proteins and Peptides / Q000302:isolation & purification / Q000494:pharmacology; D013552:Swine
chemical_list: D000596:Amino Acids; D002241:Carbohydrates; D012471:Salivary Proteins and Peptides