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目的分离、鉴定99mTc-depreotide异构体,并比较其生物活性。方法采用高压液相色谱仪分离99mTc-depreotide的一对顺式和反式异构体,采用质谱、CD光谱、1 H NMR分析异构体的结构特征,比较A549细胞对这对异构体的受体亲和性。结果高压液相色谱仪分离的顺式和反式异构体的含量比约为90∶10,顺式和反式异构体的分子质量均为1 469.5,均有不同的科顿效应;1 H NMR结果可显示二者的氨基酸序列和结构特征;顺式异构体的受体亲和性明显高于反式异构体(P<0.01)。结论 99mTc-depreotide存在顺式和反式异构体,且生物活性不同,在实际应用中应将2个异构体视作2个化合物。
Objective To isolate and identify 99mTc-depreotide isoforms and compare their bioactivity. METHODS: A pair of cis and trans isoforms of 99mTc-depreotide was isolated by high pressure liquid chromatography (HPLC). The structures of the isomers were analyzed by mass spectrometry, CD spectroscopy and 1 H NMR. Receptor affinity. Results The content ratio of cis and trans isomers separated by high pressure liquid chromatography was about 90:10, and the molecular mass of both cis and trans isomers was 1 469.5, which had different Cotton effect; 1 H NMR results showed the amino acid sequence and structural characteristics of the two isomers; cis receptor is significantly higher than the trans isomer (P <0.01). Conclusion 99mTc-depreotide has cis-and trans-isomers with different biological activities. Two isomers should be considered as two compounds in practical application.