Chin. J. Org. Chem. ›› 2017, Vol. 37 ›› Issue (9): 2409-2415.DOI: 10.6023/cjoc201704020 Previous Articles     Next Articles



葛巍巍a,b, 陈静a, 张也a, 宗良a, 张鸣a, 董俊军a   

  1. a 中国人民解放军防化学院生化防护系 北京 102205;
    b 公安消防部队高等专科学校训练部 昆明 650208
  • 收稿日期:2017-04-12 修回日期:2017-05-15 发布日期:2017-05-25
  • 通讯作者: 董俊军
  • 基金资助:


Semiregioselective Formation of Linaclotide with Orthogonal Cysteine Protection Strategy

Ge Weiweia,b, Chen Jinga, Zhang Yea, Zong Lianga, Zhang Minga, Dong Junjuna   

  1. a Department of Bio-Chem Defence, Institute of Nuclear, Biological and Chemical Defence, Beijing 102205;
    b Department of Training, Public Security Fire Forces College, Kunming 650208
  • Received:2017-04-12 Revised:2017-05-15 Published:2017-05-25
  • Contact: 10.6023/cjoc201704020
  • Supported by:

    Project supported by the State Key Laboratory of Toxicology and Medical Countermeasures of China (No. PMC201507) and the State Key Laboratory of Nuclear, Biological and Chemical Protection for Civilian (No. SKLNBC2013-01K).

Six linear precursors of linaclotide containing different protected cysteine residues were synthesized by Fmoc solid-phase methods. Wang resin was used in the peptide syntheses. The protective groups of cysteine thiol were trityl (Trt) and acetamidomethyl (Acm) in the different positions. The six linear precursors of linaclotide include three[4 Trt+2 Acm] and three[2 Trt+4 Acm] ones. The linaclotide with three disulfide bonds was prepared from these linear precursors by semiregioselective strategy. Firstly, linear peptides were cleaved from Wang resins by TFA-TIS-H2O. At the same time, the Trt groups were removed to give free thiol groups, whereas Acm groups were still remained in the peptides. Secondly, the free thiol groups were oxidized by 20% hemin/DIEA system to from disulfide bond(s). Finally, cysteines containing Acm groups were deprotected by CH3SiCl3/PhS(O)Ph/TFA coaktail and disulfide bond(s) were formed simultaneously. The precursors of peptides[4 Trt(2,5,10,13)+2 Acm(1,6)],[2 Trt(1,6)+4 Acm(2,5,10,13)] and[2 Trt(5,13)+2 Acm(1,2,6,10)] give linaclotide at the conversion ratios of 71.9%, 31.5%, and 81.4% respectively. Other three peptides failed in the conversion or were found to be less suitable to prepare linaclotide. Our results indicated that the order of disulfide bond formation is very important to prepare linaclotide by using semiregioselective or regioselective strategies. The Cys5-Cys13 disulfide bond is the most privileged and should be formed firstly among the three disulfide bonds in linaclotide.

Key words: linaclotide, disulfide, oxidation, semiregioselective