Desialylation hormones

These studies demonstrating a protective effect of sialic acid residues on serum glycoproteins provide an explanation for earlier, conflicting observations about the biological effect of, for example, desialylated erythropoietin, which stimulates erythropoiesis only after direct application to bone-marrow cell-cultures, and not after injection into the blood stream.469 In the latter experiment, only the native, sialylated hormone was active. Rapid clearance and inactivation of follicle-stimulating hormone,470 or interferon,471 after treatment with sialidase may be explained by uptake into liver cells. 

Desialylated human chorionic gonadotrophin was found to be twice as effective as the native hormone in competing for the binding site of receptors in rat testis. However, it has been pointed out that caution must be exercised when radio-ligand receptors are used to assay preparations of human chorionic gonadotrophin of different sialic acid contents. 

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