title: The microfibrillar components of porcine lung elastic fiber.
abstract: Lung elastic fiber was isolated from anatomically defined porcine parenchymal tissue. Constituent microfibrillar acidic structural glycoproteins (external and meso) were obtained by mild dissociative quantitative procedures, leaving the elastin-rich fraction as the insoluble residue. The presumptive cross-link lysylnorleucine was identified in both of the highly aggregated acidic structural glycoprotein fractions. The external-acidic structural glycoproteins require dithiothreitol but not sodium dodecyl sulfate for solubility. Both sodium dodecyl sulfate and dithiothreitol at 55 degrees C are required to release meso-acidic structural glycoproteins from the elastic fiber. On the basis of physical characteristics, I propose a new fraction from elastic fiber, the meso-acidic structural glycoprotein. The meso-acidic structural glycoproteins may have been in longest and closest contact with the elastin core of the elastic fiber. Alkali-soluble peptides from the elastin-rich fraction contained desmosine and high concentrations of hydroxyproline, polar amino acids and lysylnorleucine. The cross-link, lysylnorleucine, may be evidence of covalent bonding of glycoprotein to elastin, explaining my inability to obtain the biopolymer elastin with the composition of tropoelastin corrected for the desmosine-lysine content.
mesh_terms: D000596:Amino Acids / Q000032:analysis; D000818:Animals; D002241:Carbohydrates / Q000032:analysis; D003599:Cytoskeleton / Q000032:analysis*; D004151:Dipeptides / Q000032:analysis; D004229:Dithiothreitol; D004548:Elasticity; D004549:Elastin / Q000302:isolation & purification*; D006023:Glycoproteins / Q000032:analysis*; D006909:Hydroxyproline / Q000032:analysis; D008168:Lung / Q000032:analysis*; D012995:Solubility; D013552:Swine
chemical_list: D000596:Amino Acids; D002241:Carbohydrates; D004151:Dipeptides; D006023:Glycoproteins; C002961:lysinenorleucine; D004549:Elastin; D006909:Hydroxyproline; D004229:Dithiothreitol