Nuclear Science and Techniques

《核技术》(英文版) ISSN 1001-8042 CN 31-1559/TL     2019 Impact factor 1.556

Nuclear Science and Techniques ›› 2001, Vol. 12 ›› Issue (2): 99

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Labeling polypeptide with 99mTc and bioactivity get back

LI Shao, JIANG Xiao-Fei, PANG Hua, LIU Fang-Xin, SHI Qiong   

  1. Department of Nuclear Medicine, Chongging University of Medical Sciences, Chongqing 400016
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LI Shao, JIANG Xiao-Fei, PANG Hua, LIU Fang-Xin, SHI Qiong. Labeling polypeptide with 99mTc and bioactivity get back.Nuclear Science and Techniques, 2001, 12(2): 99

Abstract: A method for labeling polypeptide (insulin) with technetium- 99(99mTc ) was established without marked loss of biological activity. Following reduction of intrinsic disulfide bonds by mercaptoethanol and purification on a Sephadex G50 column, the polypeptide was labeled with 99mTc by transchelation from methylene diphosphonate (MDP). Tc labeled insulin was identified by thin layer chromatograph (TLC) and the change of blood sugar of mice injected, their hypoglycemic shock symptom was also observed. Six hours after labeling, the dissociation of labeled insulin was only 3%, From then on to 24h, there was no more dissociation. The blood sugar concentration of mice injected with the mercaptoethanol-reduced insulin was (5.0±3.2)μmol.L-1 , while those injected with the original insulin was (1.4±1.2)μmol.L-1 , the difference was significant (Q test, p<0.01). Blood sugar concentration of the mice was 0.3 ±0.2 μmol.L-1 . for the labeled insulin. and was about the same with that for the original msulin. The labeling efficiency was 74.31% for the labeled insulin, whereas the original insulin cannot be labeled with 99mTc. The result suggests that while disulfide bonds of polypeptide were reduced by mercaptoethanol, it became free sulthydryl group, and its bioactivity descended. Then free sulfhydryl group was chelated with 99mTc under mild condition. restablishing the disulfide bond, therefore, the bioactivity came backThe 99mTc-labeled insulin was stable during 24h.

Key words: Peptides, Biological assay, Tc-labeled insulin