RÉSUMÉ
Objective: To isolate the key domain of a novel polypeptide fragment from NGN-β that functions like intact NGF molecule.Methods: NGF-β had been treated with cyanogen bromide and trypsin skillfully. The peptide fragment with the activity inducing PC12 pheochromocytoma cells differentiation was isolated and purified by Sephadex G-50 gel filtration chromatography , DE-52 celluloseion exchange chromatography and C-18 reversed-phase column HPLC after NGF-β cleavaged by CNBr at 9th met then by trypsin at Arg or Lyscleavaged by CNBr at 9th met then by trypsin at Arg or Lys. Amino acid sequencing of this novel peptide fragment was performed by Automatic Amino Acid Analyser and Amino Acid Sequencer. Results: The functional fragment from cleavaged NGF might induce differentiation of PC12 cells. The fragment was consisting of two linear polypeptides . One of them was 16 peptide, GEFSVCDSVSVWVGDK , and other was 14 peptide, HWNSYCTTTHTFVK, linked by a disulphide bridge corresponding to residues 10～25 and 75～88, respectively, of the amino acid sequence of nerve growth factor, the result of biological activity assay in PC12 cells showed that the optimum concentration of this peptide were 0.001～0.1 μg*L-1. Conclusion: A novel peptide inducing differentiation of PC12 cell line of pheochromocytoma cells was obtained in the study. It′s isolation and purification successfully will underlie synthesis or expression of hyperactive neurotrophic small molecular substance although the relationship between the configuration and functions is not clearly.