Partial purification and characterization of a lung antiproteinase and its differentiation from serum antiproteinases.

Abstract

Model of Lung Growth. Unilateral pneumonectomy in the adult rabbit is followed by a compensatory doubling of the mass of the remaining lung within one month. This growth is accompanied by an increase in the total amount of collagen in the lung, yet the concentration of collagen per unit lung mass remains constant. This phenomenon is preceded by an apparent shift in the types of proteins synthesized by the growing lung, so that collagen synthesis is more pr~minent.~ Mechanisms of CoUagen Synthesis in Lung. A cellfree protein synthesizing system has been developed which actively synthesizes lung proteins including collagen. This technique has been used to demonstrate: (1) that collagen synthesis in lung takes place on large polysomes attached to the endoplasmic reticulum and (2) that the change in the relative rate of collagen synthesized in the developing neonatal lung is due, in part, to either a change in collagen gene expression or to a change in the number of cells synthesizing ~ollagen.~ Proteolysis of Collagen Synthesized in vitro. At least some of the collagen synthesized in vitro is lost following dialysis, suggesting that there must be mechanisms present in lung explant cultures to degrade collagen following synthesis. The relative amount of collagen hydrolyzed can be quantitated and the influence of serum proteins on this process can be investigated.