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Abstract
Apparently homogenous crystalline protein fractions have been obtained from bovine, rabbit, and dog lenses by the use of ammonium sulfate fractionation methods and by a combination of these methods with DEAE-cellulose column chromatography. The proteins so obtained appear to be one of the organ specific antigens of these lenses. In addition, these fractions have a high proportion of the lactic dehydrogenase (LDH) activity of the lens of origin but the specific LDH activity is sufficiently low to cast serious doubt that the antigen is also the LDH enzyme.
While the LDH of the lens resembles the LDH of other tissues, namely, specific for L(+) lactate and DPN, catalyzes both lactate oxidation and pyruvate reduction, and has a different pH maximum for each of these reactions, at the same time it appears to be different. It remains in solution in 50 per cent saturated ammonium sulfate solutions. It is not inhibited by metal complexing compounds nor is it sensitive to phosphate concentration or sulfhydryl group reagents. It also crystallizes in a different crystalline form than does LDH of other mammalian sources.