Title: Splenin
CAS Registry Number: 1416-60-0
Additional Names: Thymopoietin III; SP
Literature References: Polypeptide hormone of the spleen which induces differentiation and maturation of both T- and B-cell precursors. Originally detected by its cross reactivity with thymopoietin, q.v., in radioimmunoassay. Human splenin (hSP) contains 48 amino acids; bovine splenin (bSP) contains 49. Splenopentin, a pentapeptide corresponding to residues 32-36, exhibits full bioactivity. The amino acid sequence of splenin is highly homologous with that of thymopoietin; the differences in bioactivity are attributed to a single amino acid substitution at position 34. Unlike the thymic hormone, splenin exhibits no neuromuscular effects. Isoln from bovine spleen and complete amino acid sequence: T. Audhya et al., Biochemistry 20, 6195 (1981). Synthesis: T. Abiko et al., Chem. Pharm. Bull. 34, 2133 (1986). Isoln and sequence of human splenin: T. Audhya et al., Proc. Natl. Acad. Sci. USA 84, 3545 (1987). Biological activities of bSP and comparison with thymopoietin: T. Audhya et al., ibid. 81, 2847 (1984). Effect on antibody production in vivo: W. Diezel et al., Biomed. Biochim. Acta 45, 1349 (1986). Effect of hSP on B-cell number in vitro: T. Abiko, H. Sekino, Chem. Pharm. Bull. 37, 391 (1989).
NOTE: The term, splenin, formerly referred to a crude mixture of bioactive substances extracted from mammalian spleen: G. Ungar, Endocrinology 37, 329 (1945). |