Audhya T, Schlesinger D H, Goldstein G
Proc Natl Acad Sci U S A. 1987 Jun;84(11):3545-9. doi: 10.1073/pnas.84.11.3545.
Human thymopoietin and splenin were isolated from human thymus and spleen, respectively, by monitoring tissue fractionation with a bovine thymopoietin RIA cross-reactive with human thymopoietin and splenin. Bovine thymopoietin and splenin are 49-amino acid polypeptides that differ by only 2 amino acids at positions 34 and 43; the change at position 34 in the active-site region changes the receptor specificities and biological activities. The complete amino acid sequences of purified human thymopoietin and splenin were determined and shown to be 48-amino acid polypeptides differing at four positions. Ten amino acids, constant within each species for thymopoietin and splenin, differ between the human and bovine polypeptides. The pentapeptide active site of thymopoietin (residues 32-36) is constant between the human and bovine thymopoietins, but position 34 in the active site of splenin has changed from glutamic acid in bovine splenin to alanine in human splenin, accounting for the biological activity of the human but not the bovine splenin on the human T-cell line MOLT-4.
人胸腺生成素和脾生成素分别从人胸腺和脾脏中分离得到，分离过程通过用与人类胸腺生成素和脾生成素具有交叉反应性的牛胸腺生成素放射免疫分析法监测组织分级分离来进行。牛胸腺生成素和脾生成素是49个氨基酸的多肽，仅在第34和43位有2个氨基酸不同；活性位点区域第34位的变化改变了受体特异性和生物学活性。已确定纯化的人胸腺生成素和脾生成素的完整氨基酸序列，显示它们是48个氨基酸的多肽，在四个位置不同。人源和牛源多肽之间有10个氨基酸不同，胸腺生成素和脾生成素在每个物种内是恒定的。胸腺生成素的五肽活性位点（第32 - 36位残基）在人源和牛源胸腺生成素之间是恒定的，但脾生成素活性位点的第34位已从牛脾生成素中的谷氨酸变为人类脾生成素中的丙氨酸，这解释了人类脾生成素而非牛脾生成素对人T细胞系MOLT - 4的生物学活性。
