Microheterogeneity in Buffalo Thyroid Stimulating Hormone

Microheterogeneity has been observed in the thyrotropin isolated from buffalo pituitary glands using the standard isolation and fractionation procedures. Crude thyrotropin was passed through CM-Sephadex column for enrichment, followed by sizing through Sephadex G-200 and ultimately DEAE-Sephacel was used for the segregation of TSH from LH. The buTSH obtained had 72% TSH immunoreactivity and a specific bioactivity of 71U/mg. It had only about 10% LH content in it. N-terminal analysis of buTSH revealed heterogeneity where the two N-termini were determined as Phe and Gly. The carbohydrate analysis of the buTSH fraction revealed the presence of three microheterogenous forms, out of which the form containing the biantennary carbohydrate structure had the highest immunoreactivity. However, buffalo TSH was found to be different from sheep TSH. The latter appears to have a high mannose/hybrid carbohydrate structure in the most immunoreactive fraction.