Computational Exploration of Conformations of Glycine-Arginine and a Deduced Model on Global Minimum Configurations of Dipeptides in Gas Phase

An extensive computational study on the conformations of gaseous dipeptide glycinearginine, GlyArg, has been performed. A large number of trail structures were generated by systematically sampling the potential energy surface (PES) of GlyArg. The trial structures were successively optimized with the methods of PM3, HF/3-21G^*, BHandHLYP/6-31G^*, and BHandHLYP/6-311++G^** in order to reliably find the low energy conformations. The conformational energies were finally determined with the methods of BHandHLYP, camB3LYP, B97D, and MP2 using the basis set of 6-311++G(3df,3pd). The results establish firmly that gaseous GlyArg exists primarily in its canonical form, in sharp contrast with ArgGly that adopts the zwitterionic form. Important data such as the rotational constants, dipole moments, vertical ionization energies, temperature distributions and IR spectra of the low energy conformers are represented for the understanding of the future experiments. Moreover, considering the global minima of all amino acids and many dipeptides, combined with the hydrophobicities of amino acids, a model predicting whether the global minimum configuration of a dipeptide is canonical or zwitterionic is developed.     

4:3-β-naphthapyrone-4-acetic acidN-hydroxysuccinimidyl ester as a fluorescent labeling reagent for amino acids and oligopeptides in high-performance liquid chromatography

Summary 4:3-β-Naphthapyrone-4-acetic acidN-hydroxysuccinimidyl ester (NPA-OSu) is a highly sensitive and moderately reactive derivatizing reagent with a naphthapyrone moiety as fluorophore and anN-hydroxysuccinimidyl active ester as reactive group toward amino compounds. It is readily prepared in two steps. The fluorescence properties of NPA-OSu and its hydrolysis product have been studied in detail, and the conditions for derivatization and separation of the NPA-OSu derivatives of some amino acids and oligopeptides have been investigated. Atλ _ex = 352 nm andλ _em = 422 nm the detection limits (signal-to-noise ratio=3) for amino acids and oligopeptides reached fmol levels, for injection of 20 μL; this sensitivity was comparable with that obtained by use of 7-(diethylamino)coumarin-3-carboxylic acid succinimidyl ester as derivatizing reagent in the analysis of amino acids by capillary electrophoresis with laser-induced-fluorescence detection.     

姬松茸低聚肽的制备及性质

采用超临界CO2萃取对姬松茸进行脱脂处理后, 用微波提取姬松茸多糖, 以脱脂脱多糖的姬松茸为原料, 采用双酶法制取姬松茸低聚肽, 并对姬松茸低聚肽的抗氧化能力进行了研究. 结果表明, Alcalase 2.4L碱性蛋白酶的最佳酶解条件为: pH=8.5, 温度55 ℃, 酶解时间2 h, 底物浓度5％, 酶用量1.5％, 肽得率为74.7%. Flavourzyme风味蛋白酶最佳酶解的条件为: pH=7.0, 温度50 ℃, 时间1.5 h, 酶用量为4％, 最终肽得率为80.6%. 姬松茸低聚肽分子量集中在5600以下, 人体必需氨基酸含量为50.91%(质量分数). 姬松茸低聚肽对邻苯三酚自氧化具有明显的抑制作用, 抑制率为35.6%.     

Synthesis and anti-HIV-1 activity of the conjugates of gossypol with oligopeptides and D-glucosamine

A series of novel gossypol derivatives were synthesized and screened for their in vitro anti-HIV- 1I activity. The results showed that replacing the aldehyde groups of gossypol with certain oligopeptides and Dglucosamine not only reduced the cytotoxicity of gossypol derivatives but also enhanced their antiviral activity against HIV-1. Interestingly, D-glucosamine derivative of gossypol that lacked the COONa group also exhibited the same potent anti-HIV-1 activity as oligopeptide derivatives with the COONa group. These compounds blocked the entry of HIV-1ⅢB into target cell. which was similar to T20. Furthermore, the molecular docking analysis rationalized their anti-HIV-1 activity. The results also implied that certain oligopeptides and D-glucosamine were important moities to prepare gossypol derivatives as HIV- 1 entry inhibitors besides certain amino acids.     

甘氨酸精氨酸二肽的结构计算和二肽气相最低能构象模型

研究了气相下的甘氨酸精氨酸二肽体系．在考虑三种异构体内轴转动时对势能面进行了系统采样．大量的初始构型经PM3、 HF/3-21G^*、 BHandHLYP/6-31G^*及BHandHLYP/6-311++G^**方法逐级优化获取了最终的稳定构型,低能的结构进一步运用BHandHLYP、cam-B3LYP、 B97D及MP2方法在6-311++G(3df,3pd)基组下进行了单点能计算．计算了重要构象的转动常量、偶极矩、垂直电离能、温度分布及红外光谱．最终数据表明,气相GlyArg主要以电中性的状态存在,参考所有的氨基酸及部分二肽的稳定结构特征,结合各类氨基酸的疏水性,归纳出了各种不同二肽的最低能构象是中性或双电性构型的理论模型．     

Nanoscale substrate recognition by porphyrin dendrimers with patched structures

Dendrimer technology has enabled us to build macromolecules with nanosized defined structures. By introducing unsymmetrical patched structures in dendrimers, sophisticated artificial receptors exhibiting nanoscale substrate recognition can be obtained. In this review article, our recent studies on molecular recognition by porphyrin dendrimers with patched structures are summarized. Three topics are presented: (1) oligopeptide-patched dendrimers as a nanoscale receptor of cytochrome c protein; (2) pocket dendrimers as a nanoscale receptor for bimolecular guest accommodation; and (3) energy transfer in unsymmetrical dendrimers. These dendrimers nicely mimic proteins and enzymes, and also act as photofunctional artificial receptors, in which porphyrin’s strong photoabsorption and intense fluorescence signals can respond sensitively to the substrate binding.     

5-氟尿嘧啶N1-甲酰基氨基酸、短肽的合成及抗肿瘤活性

5-氟尿嘧啶N¹-甲酰氯分别与Gly、Val、Leu、Ile、Phe、Asp和Glu的苄酯反应,制备了7种5-氟尿嘧啶-N¹-甲酰基氨基酸苄酯。氢解后得到了相应的5-氟尿嘧啶N¹-甲酰氨基酸。将其进一步与氨基酸甲酯或二肽甲酯缩合,制备了5-氟尿嘧啶N¹-甲酰基二肽甲酯和三肽甲酯。5-氟尿嘧啶-N¹-甲酰基二肽甲酯也可采用5-氟尿嘧啶-N¹-甲酰氯与二肽甲酯直接反应制备。