Elastic properties of the lung are of a major importance to gas exchange. Decreased lung functions, especially those observed with the emphysemas and in aging, may be the result of changes in the elastic tissue in which decreased alveolar extensibility, fragmentation of the elastic continuum and decreased gas exchange have been observed histologically and measured physiologically. However, little is presently known of the quantitative and qualitative biochemical properties of the lung elastic tissue components at the molecular level. We will develop techniques for separation of lung parenchymal tissue from the bronchiolar systems, using swine lung. New, mild procedures largely developed in our laboratory, will be used for quantitative isolation of lung elastic fiber and component acidic structural glycoprotein and elastin samples. Using these initial purification steps, these proteins are less likely to contain artifacts and hence are suitable to use for sensitive qualitative biochemical measurements. These measurements will then allow us to determine certain biochemical interrelationships within the elastic fiber. An ultimate aim of this research is to determine biochemical changes in structural glycoprotein, a soluble complex resembling acidic structural glycoprotein and elastin samples from the elastin core, which may be responsible for the fragmentation and thinning of elastic fiber in diseased or aged lung for which histological evidence of damaged elastic fiber agrees well with altered elastic recoil.