Further studies on the purification and properties of a ribonuclease inhibitor from lens cortex

Abstract

A ribonuclease inhibitor protein has been purified 500-fold from a crude extract of bovine lens cortex. This protein has a molecular weight of 32,000 as determined by Sephadex gel filtration and migrates as a very acidic protein in disk electrophoresis. The inhibition of ribonuclease appears to involve the formation of an inactive ribonuclease-inhibitor complex. This complex was shown to have a molecular weight of 48,000 which indicates a 1:1 stoichiometry. The formation of this complex depends upon charge interaction since the presence of poly- l-lysine interferes with the inhibition of ribonuclease. Data are also preseted which show that there is no difference in absolute ribonuclease activity between normal and cataractous lenses, and that ribonuclease activity in the lens is located mainly in the lens epithelium.