Isolation of a soluble cadmium-binding protein from pulmonary macrophages
Cox, C.C.; Waters, M.D.
Toxicology and Applied Pharmacology 46(2): 385-394
1978
ISSN/ISBN: 0041-008X PMID: 734667 Document Number: 138379
A soluble Cd binding protein, with properties similar to metallothionein, was isolated from rabbit alveolar macrophages. The macrophages were cultured in Medium 199 with Earle's salts for 24 h in the presence of 10 .mu.M CdCl2 and carrier-free 109Cd as a tracer. The isolation procedure began with application of a 100,000 g cell supernatant to a column of Sephadex G-75 Fine. The fraction containing the greatest amount of Cd was eluted at a relative elution volume, Ve/Vo, of 1.87. A MW determination performed following Sephadex chromatography indicated that the apparent MW of the impure protein was approximately 11,000. The fractions containing Cd were pooled and purification procedures were applied, including acetone fractionation, DEAE-cellulose chromatography and polyacrylamide gel electrophoresis. DEAE-cellulose chromatography following acetone fractionation indicated the presence of 2 forms of metalloprotein as demonstrated previously in the isolation of Cd-thionein from liver and kidney. The 2 forms of metalloprotein were subjected to polyacrylamide gel electrophoresis and, although separation was incomplete, bands obtained corresponded to those typically observed in rat liver.