研究预处理和提取方法对杜仲橡胶提取效率的影响。结果表明:与超微粉碎预处理相比,生物酶解预处理能更好地保留杜仲橡胶在杜仲植物中的原貌,制得的杜仲橡胶的重均相对分子质量大(超过4.2×105),相对分子质量分布略宽;与常规提取相比...研究预处理和提取方法对杜仲橡胶提取效率的影响。结果表明:与超微粉碎预处理相比,生物酶解预处理能更好地保留杜仲橡胶在杜仲植物中的原貌,制得的杜仲橡胶的重均相对分子质量大(超过4.2×105),相对分子质量分布略宽;与常规提取相比,超声波提取的提取效率较高。采用生物酶解预处理、超声波提取(温度为50℃,时间为30 min,超声波频率为40 k Hz),杜仲橡胶的提取效率较高且能耗适中。展开更多
The aminopeptidase gene from thermophilic archaea Sulfolobustokodaii was cloned and expressed in Escherichia coli BL21 codon-plus（DE3）. To overexpress the aminopeptidase, the vector pET32a was constructed, in which ...The aminopeptidase gene from thermophilic archaea Sulfolobustokodaii was cloned and expressed in Escherichia coli BL21 codon-plus（DE3）. To overexpress the aminopeptidase, the vector pET32a was constructed, in which the target gene was fused with the genes of histidine-tag and thioredoxin（Trx）. The expressed protein was purified using Ni^2＋-column affinity chromatography and ion exchange chromatography and cleft with enterokinase（EK） to obtain the purified aminopeptidase（ST1737）. The biochemical and enzymic properties of the expressed ST1737 were characterized. The results show that its optimal pH and temperature are 8 and 80 ℃, respectively. The half-life of ST1737（0.2 mg/mL） is about 85 h at 90 ℃, indicating that the enzyme exhibits an excellent thermostability. The activity of ST1737 could still maintain over 85% after its treatment at 25 ℃ in different buffers with a pH range of from 6.0 to 10.5 for 24 h, demonstrating that ST1737 is stable in neutral or slight alkali environment. The enzyme shows a high activity for the substrates such as unmodified peptide Asp-Ala, while the pNPC8 shows an optimal esterase substrate specificity. These results indicate that the enzyme is a bifunctional enzyme, and different from the aminopeptidase reported before.展开更多
文摘研究预处理和提取方法对杜仲橡胶提取效率的影响。结果表明:与超微粉碎预处理相比,生物酶解预处理能更好地保留杜仲橡胶在杜仲植物中的原貌,制得的杜仲橡胶的重均相对分子质量大(超过4.2×105),相对分子质量分布略宽;与常规提取相比,超声波提取的提取效率较高。采用生物酶解预处理、超声波提取(温度为50℃,时间为30 min,超声波频率为40 k Hz),杜仲橡胶的提取效率较高且能耗适中。
基金Supported by the National Natural Science Foundation of China（No.20772046）.
文摘The aminopeptidase gene from thermophilic archaea Sulfolobustokodaii was cloned and expressed in Escherichia coli BL21 codon-plus（DE3）. To overexpress the aminopeptidase, the vector pET32a was constructed, in which the target gene was fused with the genes of histidine-tag and thioredoxin（Trx）. The expressed protein was purified using Ni^2＋-column affinity chromatography and ion exchange chromatography and cleft with enterokinase（EK） to obtain the purified aminopeptidase（ST1737）. The biochemical and enzymic properties of the expressed ST1737 were characterized. The results show that its optimal pH and temperature are 8 and 80 ℃, respectively. The half-life of ST1737（0.2 mg/mL） is about 85 h at 90 ℃, indicating that the enzyme exhibits an excellent thermostability. The activity of ST1737 could still maintain over 85% after its treatment at 25 ℃ in different buffers with a pH range of from 6.0 to 10.5 for 24 h, demonstrating that ST1737 is stable in neutral or slight alkali environment. The enzyme shows a high activity for the substrates such as unmodified peptide Asp-Ala, while the pNPC8 shows an optimal esterase substrate specificity. These results indicate that the enzyme is a bifunctional enzyme, and different from the aminopeptidase reported before.
