共查询到20条相似文献,搜索用时 31 毫秒
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David R. ColemanIV Kumaralal Kaluarachchi Zhiyong Ren Xiaomin Chen John S. McMurray 《International journal of peptide research and therapeutics》2008,14(1):1-9
To answer the question of whether the conformation of the Leu-Pro bond is cis or trans in Ac-pTyr-Leu-Pro-Gln-Thr-Val-NH2 when complexed with the SH2 domain of Stat3, we substituted 2,2-dimethyloxazolidines derived from serine (Ser(ΨMe,Mepro)) and threonine (Thr(ΨMe,Mepro)) for proline. The 2,2-dimethyloxazolidine and 2,2-dimethylthiazolidine pseudoproline (ΨPro) analogs induce predominantly
cis Xxx-ΨPro peptide bonds. As these ΨPro analogs are acid-labile, the phosphopeptides were synthesized using Fmoc-based SPPS
using unprotected phosphotyrosine and 4-hydroxybenzoate as the linker that allowed release from the support by alkaline ammonolysis,
conditions that kept the oxazolidine rings intact. Incorporation of Ser(ΨMe,Mepro) resulted in 69% cis Leu-ΨPro bond content in aqueous solution whereas that for Thr(ΨMe,Mepro) analog was 63%. Affinities for Stat3 were 3–5 fold lower than the lead compound and were inversely correlated with cis content. Thus we conclude that the Leu-Pro peptide bond is trans when the peptide is bound to Stat3. 相似文献
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Shan Huang Da Zhou Yu-Xuan Li Zhi-Yong Ming Ke-Zhi Li Guo-Bin Wu Chuang Chen Yin-Nong Zhao 《Journal of cellular physiology》2019,234(4):3500-3514
Hepatocellular carcinoma (HCC), as the third leading cancer-caused deaths, prevails with high mortality, and affects more than half a million individuals per year worldwide. A former study revealed that microRNA-221 (miR-221) was involved in cell proliferation of liver cancer and HCC development. The current study aims to evaluate whether miR-221 targeting SOCS3 affects HCC through JAK–STAT3 signaling pathway. A series of miR-221 mimic, miR-221 inhibitor, siRNA against SOCS3, and SOCS3 plasmids were introduced to SMMC7721 cells with the highest miR-221 expression assessed. The expression of JAK–STAT3 signaling pathway–related genes and proteins was determined by Western blot analysis. Cell apoptosis, viability, migration, and invasion were evaluated by means of flow cytometry, 3-(4,5-dimethylthiazol-2-yl)-2,5 diphenyl tetrazolium bromide, and transwell assays, respectively. HCC xenograft in nude mice was performed to measure HCC tumor growth. miR-221 was found to be highly expressed but SOCS3 was poorly expressed in HCC tissues. miR-221 expression was correlated with lymph node metastasis (LNM) and tumor node metastasis (TNM) of HCC, and SOCS3 expression was correlated with LNM, differentiation and TNM of HCC. SOCS3 is a target gene of miR-221. MiR-221 mimic or si-SOCS3 exposure was found to induce cell viability, migration, and invasion, and reduce apoptosis. MiR-221 inhibitor was observed to have inhibitory effects on HCC cell proliferation, migration, and invasion. Moreover, the expression of JAK–STAT3 signaling pathway was suppressed by miR-221 inhibitor. Downregulated miR-221 expression could promote its target gene SOCS3 to inhibit the proliferation, invasion and migration of HCC cells by repressing JAK–STAT3 signaling pathway. 相似文献
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Maokun Sun Shuai Guo Jie Yao Yilei Xiao Ruili Sun Wenyi Ma Zhaogang Dong 《Journal of cellular biochemistry》2019,120(2):1894-1902