Screening Mimotopes Of Somatostatin With Phage 12-mer Peptides Library

Somatostatin is a peptide hormone having fourteen amino acid secreted from hypothalamus. The main physiological action of somatostatin is inhibit secreting of growth hormone.The results of this experiment are summarized as following:1. A prokaryotic expressing plamid pET-32a-ss was constructed and expressed in E.coli BL21(DE3). After induced by IPTG, an expressied protein was obtained and it's molecular weight was approximately 23.4 KD by SDS-PAGE .2. The specific sera were obtained by immunizing rabbits with somatostatin vaccine. After purified with saturated ammonia sulphate, the IgG was purified through DEAE-sephadex-A50 low pressure chromatography system. The IgG was tested by SDS-PAGE and it's content was measured using radioimmunoassay. Then the IgG was used as target, to screen the phage display 12-mer random peptides library for 4 rounds by competitive elution and absorption with negative sera. 22 clones eluted from the 4rd panning were picked out randomly and characterized. Six positive clones among 22 clones were identifited by ELISA and competitive ELISA. The ssDNA of the 6 positive clones were abstracted and sequenced . The results showed that five clones of them had the same sequence. Compared with somatostatin amino acid sequence, the homogerous sequence was FWK.