STUDIES OF HUMAN PULMONARY CONNECTIVE TISSUE .3. CHEMICAL CHANGES IN STRUCTURAL PROTEINS WITH EMPHYSEMA

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Abstract
Changes with aging of the structural proteins of lung include an increased resistance of fibrous collagen to enzymatic digestion and to autoclaving, and of elastic protein to digestion with pancreatic elastase. Connective tissue from lungs with severe anatomic emphysema showed amounts and types of fibrous proteins similar to those present in other adult lungs. Three major fractions were isolated following elastase digestion and gel filtration of components of lung crude connective tissue fibers. The larger sized glycopolypeptides were fluorescent, contained desmosine and hydroxylysine, and sialic acid, fucose, glucose, mannose, and galactose on gentle acid hydrolysis. They showed little significant variation in chemical composition in persons of different ages or in emphysematous subjects. The smallest sized polypeptide fraction showed striking increases in aromatic and basic amino acids, with reduced content of neutral amino acids in a male infant and in adult males dying with emphysema. These changes strongly suggest the presence of a genetic disorder involving elastic protein synthesis or metabolism that may be unique to lung connective tissue in emphysema.