Plasma 3S γ1-Globulin: Identity with Erythrocyte Carbonic Anhydrase B

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Science  03 May 1968:
Vol. 160, Issue 3827, pp. 538-539
DOI: 10.1126/science.160.3827.538


The 3S γ1, 2S γ2, and 0.5S γ2 fractions of human plasma are heterogeneous in protein composition. Although each fraction contained a relatively small amount of protein antigenically related to the immunoglobulin light chains, most of the proteins were unrelated to immunogloublin G or its light chains. Of the 3S γ1-globulins the greater part was immunochemically identical to carbonic anhydrase B and had carbonic anhydrase activity. These findings explain earlier reports of an immunochemical similarity between 3S γ1-globulins and immunoglobulin light chains in spite of marked differences in amino acid and peptide composition between the two. Apparently not all plasma γ-globulins are necessarily immunoglobulins.

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