Construction and Structure of Anti-ribavirin Single-chain Antibody Gene
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摘要:
目的 克隆构建利巴韦林(RBV)单链抗体(scFv)基因,对其理化特性进行分析并对蛋白质结构进行模拟,为后期检测方法的建立及分子改造提供参考依据。 方法 以分泌利巴韦林抗体的杂交瘤细胞株总RNA为模板,通过RT-PCR技术扩增抗体的重链可变区(VH)和轻链可变区(VL),然后以柔性连接短肽(Gly4Ser)3为接头拼接完整的scFv-RBV。利用生物信息学方法对scFv-RBV的理化性质及蛋白结构功能进行预测分析。 结果 构建的scFv基因编码240个氨基酸,相对分子质量为26 162.27 Da,理论等电点(pI)为8.57。在二级结构中,β-折叠(39.17%)和无规卷曲(45.41%)占主导地位,α-螺旋(5.42%)和β-转角(10%)相对较少。在三级结构中,VH和VL区域被Linker相互牵拉靠近,形成典型的口袋样形状的空间构象,符合单链抗体的结构特征,理论上可以与RBV抗原特异性结合。 结论 成功构建scFv-RBV基因,并利用生物信息学方法预测分析scFv的二级、三级结构,该结果可为后期进行单链抗体的表达、纯化及定向进化提供理论支撑。 -
关键词:
- 利巴韦林(RBV) /
- 单链抗体(scFv) /
- 生物信息学 /
- 结构预测
Abstract:Objective The ribavirin (RBV) single-chain antibody (scFv) gene was constructed, cloned, and physiochemically analyzed to establish a model for the detection method development and molecular modification. Method Using the total RNA of the hybridoma cell line secreting RBV antibody as a template, both heavy-chain (VH) and light-chain variable (VL) regions of the antibody were amplified by RT-PCR. Then the short peptide (Gly4Ser)3 was employed as the splicing joint to construct the complete scFv-RBV. Bioinformatics methods were applied to predict and analyze the physiochemical properties, protein structure, and functions of the gene. Results The constructed scFv-RBV encoded 240 amino acids with a relative molecular mass of 26,162.27 Da and a theoretical isoelectric point of 8.57. The secondary structure of the protein consisted of 39.17% β-sheets, 45.41% random coils, 5.42% α-helices, and 10% β-turns. In the tertiary structure, the VH and VL regions were pulled close by Linker, forming a typical pocket-like spatial configuration that conforms to the structural characteristics of a single-chain antibody. Theoretically, it could bind specifically to RBV antigens. Conclusion The successfully constructed scFv-RBV in this study afforded the utilization of bioinformatics methods to predict and analyze the secondary and tertiary structures of scFv gene paving the way for further studies on the expression, purification, and directed evolution of the single-chain antibodies. -
表 1 扩增scFv-RBV基因的引物序列
Table 1. Primer sequence for amplifying scFv-RBV
引物名称
Primer name引物序列(5′-3′)
Primer sequence (5'-3')VH-F AGG TSM ARC TGC AGS AGT TWGG VH-B TGA GGA GAC GGT GAC TGT GGT TCC TTG GCC CC VL-F GAC ATT GAG CTC ACC CAG TCT CCC VL-B ACG TTT GAT TTC CAG CTT GGT GCC VH-linker-For TTTTGGCCCAGCCGGCCC GGAGGTGAAGCTGGTGGA VH-linker-Back TCCACCGCCAGAACCTCCGCCACCAGAACCTCCACCGCC TGAGGAGACTGTGAGAGT VL-linker-For GGTGGCGGAGGTTCTGGCGGTGGAGGTTCG GA TA TCCAGA TGACACAGT VL-linker-Back TTTT GCGGCCGCTTA GGA TACAGTTGGTGCAG 注:VH-linker-For中的划线处为Sfi Ⅰ酶切位点;VL-linker-Back划线处为Not Ⅰ酶切位点; VH-linker-Back和VL-linker-For划线处为Linker序列。
Note: The underline in VH-linker-For is the Sfi Ⅰ restriction site; the underline in VL-linker-Back is the Not Ⅰ restriction site;The underlined VH-linker-Back and VL-linker-For are the Linker sequence.表 2 反转录cDNA的反应体系
Table 2. Reaction system of cDNA’s reverse transcription
试剂
Reagent体积
Volume/μL5 × PrimeScript RT master mix 4 Total RNA 10 ddH2O 6 注:反应条件:37 ℃ 15 min;85 ℃ 5 s;4 ℃保存。
Note:Eaction conditions: 37 ℃ for 15 min; 85 ℃ for 5 s; Storage at 4 ℃.表 3 PCR扩增VH和VL基因
Table 3. Amplification of VH and VL genes by PCR
样品
Sample体积
Volume/µL2 × Taq master mix 10 cDNA 1 VH-F/VL-F 1 VH-R/VL-R 1 ddH2O 7 注:反应条件:96 ℃ 5 min;96 ℃ 30 s,55 ℃ 30 s,30个循环;72 ℃ 10 min;4 ℃保存。
Note: Reaction conditions: 96 ℃ for 5 min; 96 ℃ for 30 s, 55 ℃ for 30 s, 30 cycles; 72 ℃ for 10 min; Storage at 4 ℃.表 4 scFv基因PCR反应体系(step1)
Table 4. PCR reaction system for scFv gene (step 1)
样品
Sample体积
Volume/µL2 × phanta max buffer 2 × phanta max buffer 25 dNTP mixture dNTP mixture 1 HS DNA polymerase HS DNA polymerase 1 VH VL 1 VH-linker-For VL-linker-For 1 VH-linker-Back VL-linker-Back 1 ddH2O ddH2O 20 注:PCR扩增程序:96 ℃ 90 s;96 ℃ 30 s,63 ℃ 30 s,72 ℃ 30 s,10个循环;72 ℃ 10 min;4 ℃保存。
Note: PCR amplification program: 96 ℃ 90 s; 96 ℃ 30 s, 63 ℃ 30 s, 72 ℃ 30 s, 10 cycles; 72 ℃ 10 min; store at 4 ℃.表 5 scFv基因PCR反应体系(step 2)
Table 5. PCR reaction system for scFv gene (step 2)
样品
Sample体积
Volume/µL2 × phanta max buffer 25 dNTP 1 HS DNA polymerase 1 上述反应产物 Among all above 10 VH-linker-For 1 VL-linker-Back 1 ddH2O 11 注:PCR扩增程序同表4。
Note: The PCR amplification procedure is the same as table 4.表 6 scFv基因与pCANTAB-5E载体连接体系
Table 6. scFv gene linked with pCANTAB-5E vector
样品Sample 体积Volume/µL T4 Ligation buffer(10 ×) 2 T4 DNA连接酶
T4 DNA ligase1 scFv酶切纯化产物
scFv enzyme digestion purified product1 pCANTAB-5E酶切纯化产物
pCANTAB-5E enzyme digestion purified product3 ddH2O 13 注:连接条件:16 ℃过夜。
Note: Connection conditions: 16 ℃ overnight. -
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