The title compounds were prepared by the enzymatic resolution of the corresponding N-acetylated DL-amino acids methyl esters, which were obtained from t-butyl chloride via an 8-step synthesis.
Chemical synthesis of peptides and proteins has evolved into an indispensable tool for chemical biology. Peptide ligation is a straightforward technique for joining two short peptide fragments together via a native pe...Chemical synthesis of peptides and proteins has evolved into an indispensable tool for chemical biology. Peptide ligation is a straightforward technique for joining two short peptide fragments together via a native peptide bond to afford a larger natural peptide or protein. However, the junction sites are limited to several specific amino acids because most peptide ligations involve participation of the side-chain functional groups of the junction-site amino acids. To overcome such intrinsic limitations, "general"peptide ligations which do not rely on the side-chain functional group have been developed. This review summarized the recent developments in peptide ligations that are independent of side-chain functional group of ligation-junction-site amino acid.展开更多
The effects of the amino, hydroxyl, imidazole and carboxyl groups of Ser His on DNA cleavage reaction were studied. It was found that the amino and hydroxyl groups were essential for the DNA cleavage activity of Ser H...The effects of the amino, hydroxyl, imidazole and carboxyl groups of Ser His on DNA cleavage reaction were studied. It was found that the amino and hydroxyl groups were essential for the DNA cleavage activity of Ser His, and that anyone of them blocked would result into the loss of cleavage activity. The carboxyl group was not the necessary group. The presence of the imidazole group would enhance the cleavage activity. However, the histidyl serine dipeptide, as the formula isomer of Ser His with the inverse peptide sequence, could not cleave DNA at all. Based on the above experimental results, a presumed cleavage mechanism of Ser His on DNA was proposed. [WT5HZ]展开更多
羟基硅油(HSO)和N-(β-氨乙基)-γ-氨丙基甲基二甲氧基硅烷(DL-602)先通过本体聚合反应制得侧链氨基聚硅氧烷(ASO-1),之后与异佛尔酮二异氰酸酯(IPDI)、聚醚二元醇(PEG-1000)等为原料合成的聚氨酯预聚体发生反应,制备了一种交联网络结...羟基硅油(HSO)和N-(β-氨乙基)-γ-氨丙基甲基二甲氧基硅烷(DL-602)先通过本体聚合反应制得侧链氨基聚硅氧烷(ASO-1),之后与异佛尔酮二异氰酸酯(IPDI)、聚醚二元醇(PEG-1000)等为原料合成的聚氨酯预聚体发生反应,制备了一种交联网络结构的聚氨酯改性侧链氨基聚硅氧烷(PUASO-1)。用红外光谱(IR)、核磁共振氢谱(1H-NMR)、扫描电子显微镜(SEM)等对PUASO-1进行结构表征、成膜性观察及应用性能的研究。结果表明,PUASO-1易乳化为平均粒径为135.8 nm,电位为54.1 m V的乳液PUAS-1;将PUAS-1应用于棉织物的后整理,能使处理后的棉纤维表面光滑平整。当ASO-1的氨值为0.3 mmol/g、聚氨酯(PU)质量分数为20%,PUAS-1质量浓度为10 g/L,焙烘温度170℃,焙烘时间90 s时,经PUAS-1整理后的棉织物弯曲刚度达到813 m N,白度为81.83,静态吸水时间为1.41 s,折皱回复角达到196.71°。展开更多
应用量子化学方法,分别在气相和水溶液中对氨基酸侧链与氧化鸟嘌呤碱基对(8-oxo-G∶C)形成的三体复合物的氢键键能、几何结构、电荷分布及二阶稳定化能进行了研究.结果表明,水溶液的存在削弱了复合物中的氢键强度,电荷分布变化明显,水...应用量子化学方法,分别在气相和水溶液中对氨基酸侧链与氧化鸟嘌呤碱基对(8-oxo-G∶C)形成的三体复合物的氢键键能、几何结构、电荷分布及二阶稳定化能进行了研究.结果表明,水溶液的存在削弱了复合物中的氢键强度,电荷分布变化明显,水溶液中形成氢键位点的电荷变化量约为气相中的10倍,而几何结构变化不明显、对于酶与DNA之间的相互作用的研究需在水溶液中进行.水溶液对带电三体复合物中8-oxo-G∶C与氨基酸侧链间的氢键有较大影响,键能平均减小了69.23 k J/mol,不带电复合物仅减小了3.60k J/mol.水溶液中三体复合物中8-oxo-G∶C间的氢键受侧链的影响不大,且与侧链带电与否无关,带电复合物和不带电复合物的氢键强度分别减小了24.57和30.05 k J/mol,且二阶稳定化能越大,其对应的氢键键长越短.展开更多
基金This work was supported by the Natural Science Foundation of Jiangsu Province.
文摘The title compounds were prepared by the enzymatic resolution of the corresponding N-acetylated DL-amino acids methyl esters, which were obtained from t-butyl chloride via an 8-step synthesis.
基金supported by the National Natural Science Foundation of China (21462023), and the Natural Science Foundation of Jiangxi Province (20143ACB20007, 20153BCB23018)
文摘Chemical synthesis of peptides and proteins has evolved into an indispensable tool for chemical biology. Peptide ligation is a straightforward technique for joining two short peptide fragments together via a native peptide bond to afford a larger natural peptide or protein. However, the junction sites are limited to several specific amino acids because most peptide ligations involve participation of the side-chain functional groups of the junction-site amino acids. To overcome such intrinsic limitations, "general"peptide ligations which do not rely on the side-chain functional group have been developed. This review summarized the recent developments in peptide ligations that are independent of side-chain functional group of ligation-junction-site amino acid.
文摘The effects of the amino, hydroxyl, imidazole and carboxyl groups of Ser His on DNA cleavage reaction were studied. It was found that the amino and hydroxyl groups were essential for the DNA cleavage activity of Ser His, and that anyone of them blocked would result into the loss of cleavage activity. The carboxyl group was not the necessary group. The presence of the imidazole group would enhance the cleavage activity. However, the histidyl serine dipeptide, as the formula isomer of Ser His with the inverse peptide sequence, could not cleave DNA at all. Based on the above experimental results, a presumed cleavage mechanism of Ser His on DNA was proposed. [WT5HZ]
文摘羟基硅油(HSO)和N-(β-氨乙基)-γ-氨丙基甲基二甲氧基硅烷(DL-602)先通过本体聚合反应制得侧链氨基聚硅氧烷(ASO-1),之后与异佛尔酮二异氰酸酯(IPDI)、聚醚二元醇(PEG-1000)等为原料合成的聚氨酯预聚体发生反应,制备了一种交联网络结构的聚氨酯改性侧链氨基聚硅氧烷(PUASO-1)。用红外光谱(IR)、核磁共振氢谱(1H-NMR)、扫描电子显微镜(SEM)等对PUASO-1进行结构表征、成膜性观察及应用性能的研究。结果表明,PUASO-1易乳化为平均粒径为135.8 nm,电位为54.1 m V的乳液PUAS-1;将PUAS-1应用于棉织物的后整理,能使处理后的棉纤维表面光滑平整。当ASO-1的氨值为0.3 mmol/g、聚氨酯(PU)质量分数为20%,PUAS-1质量浓度为10 g/L,焙烘温度170℃,焙烘时间90 s时,经PUAS-1整理后的棉织物弯曲刚度达到813 m N,白度为81.83,静态吸水时间为1.41 s,折皱回复角达到196.71°。
文摘应用量子化学方法,分别在气相和水溶液中对氨基酸侧链与氧化鸟嘌呤碱基对(8-oxo-G∶C)形成的三体复合物的氢键键能、几何结构、电荷分布及二阶稳定化能进行了研究.结果表明,水溶液的存在削弱了复合物中的氢键强度,电荷分布变化明显,水溶液中形成氢键位点的电荷变化量约为气相中的10倍,而几何结构变化不明显、对于酶与DNA之间的相互作用的研究需在水溶液中进行.水溶液对带电三体复合物中8-oxo-G∶C与氨基酸侧链间的氢键有较大影响,键能平均减小了69.23 k J/mol,不带电复合物仅减小了3.60k J/mol.水溶液中三体复合物中8-oxo-G∶C间的氢键受侧链的影响不大,且与侧链带电与否无关,带电复合物和不带电复合物的氢键强度分别减小了24.57和30.05 k J/mol,且二阶稳定化能越大,其对应的氢键键长越短.
