Identification and Characterization of Peptide Mimics of Blood Group A Antigen

In order to investigate peptide mimics of carbohydrate blood group A antigen, a phage display 12-mer peptide library was screened with a monoclonal antibody against blood group A antigen, NaM87-1F6. The antibody-binding properties of the selected phage peptides were evaluated by phage ELISA and phage capture assay. The peptides were co-expressed as glutathione S-transferase （GST） fusion proteins. RBC agglutination inhibition assay was performed to assess the natural blood group A antigen-mimicking ability of the fusion proteins. The results showed that seven phage clones selected bound to NaM87-1F6 specifically, among which, 6 clones bore the same peptide sequence, EYWYCGMNRTGC and another harbored a different one QIWYERTLPFTF. The two peptides were successfully expressed at the N terminal of GST protein. Both of the fusion proteins inhibited the RBC agglutination mediated by anti-A serum in a concentration-dependent manner. These results suggested that the fusion proteins based on the selected peptides could mimic the blood group A antigen and might be used as anti-A antibody-adsorbing materials when immunoabsorption was applied in ABO incompatible transplantation.

Amino acid identification and sequence analysis of peptides by reaction mass spectrometry

Fast atom bombardment mass spectrometry (FAB-MS) is applied to distinguish N- terminal series ions from C-terminal series ions of a peptide by on-probe acetylation, it provides valuable information about the sequence of an unknown peptide. The FAB mass spectra contain a number of characteristic ions at low-mass region in addition to the sequence ions at high-mass region. It was found that the ions below m/z 200 are characteristic of the amino acid composition of the peptide, from which the amino acid composition of the peptide could be estimated. Additionally, mixture analysis is also discussed.

A Novel Peptide from Buthus martensii Karch

A novel peptide was purified and characterized from Buthus martensii Karch.The peptide,named BmK M6,is a single-chain polypeptide cross-linked by four intramolecular disulfide bridges.The molecular weight of the peptide was determined by MOLDI-TOF-MS as 7034 Da.The partial amino acid sequence of BmK M6 from N-terminal is VRDAYIAKPEN CVYECGITQDCNKLCTENG.

Quantum-Chemical Description of Influence of the R-Groups on Formation of Peptide Bond

The description of influence of the R-groups on formation of the peptide bond by quantum-chemical method of density functional theory (DFT) is carried out. The criterion of probability of formation of the peptide bond has been constructed. In particular it is shown that the propensity to formation of the peptide bond is increased as a result of 1) decrease of the CO and NH bond orders (PCO and PNH) and of activation energy (ΔE#), 2) increase of OH and CN bond orders (POH and PCN), 3) exothermic property of this reaction (ΔE < 0).

A novel vector of topological and structural information for amino acids and its QSAR applications for peptides and analogues

A new descriptor, called vector of topological and structural information for coded and noncoded amino acids (VTSA), was derived by principal component analysis (PCA) from a matrix of 66 topological and structural variables of 134 amino acids. The VTSA vector was then applied into two sets of peptide quantitative structure-activity relationships or quantitative sequence-activity modelings (QSARs/QSAMs). Molded by genetic partial least squares (GPLS), support vector machine (SVM), and immune neural network (INN), good results were obtained. For the datasets of 58 angiotensin converting enzyme inhibitors (ACEI) and 89 elastase substrate catalyzed kinetics (ESCK), the R 2, cross-validation R 2, and root mean square error of estimation (RMSEE) were as follows: ACEI, R cu 2 ?0.82, Q cu 2 ?0.77, E rmse?0.44 (GPLS+SVM); ESCK, R cu 2 ?0.84, Q cu 2 ?0.82, E rmse?0.20 (GPLS+INN), respectively.

澳洲坚果抗菌肽分离纯化及其肽段鉴定与分析

以液压压榨澳洲坚果粕为原料,采用碱性蛋白酶水解制备澳洲坚果多肽(macadamia nut peptide⁃0,MNP⁃0),以对金黄色葡萄球菌与白色念珠菌的抑菌活性为跟踪指标,通过超滤、DA201⁃C型大孔吸附树脂、交联葡聚糖凝胶Sephadex G⁃25对其进行逐级分离纯化,获得抑菌活性较强的抗菌肽,并运用液相色谱串联质谱(liquid chromatography tandem mass spectrometry,LC⁃MS/MS)技术对其进行肽段组成与氨基酸序列分析。结果表明:超滤分离的不同分子量澳洲坚果多肽在所有多肽中所占质量分数不同,抑菌活性也有所差异。其中,澳洲坚果多肽组分MNP⁃4占比最高,为29.55%;抑菌活性也最强,对金黄色葡萄球菌与白色念珠菌的抑菌圈直径分别为10.01 mm与9.41 mm。大孔吸附树脂纯化多肽组分MNP⁃4的技术条件为75%乙醇溶液为解吸剂,静态吸附3 h,动态洗脱体积60 mL。经大孔吸附树脂与交联葡聚糖凝胶Sephadex G⁃25分离纯化,获得3个澳洲坚果纯化多肽(macadamia nut purified peptide,MPP)组分,其中组分MPP⁃2的抑菌活性最强,对金黄色葡萄球菌与白色念珠菌的抑菌圈直径分别为18.67 mm与16.83 mm,优于多肽MNP⁃0与超滤分离多肽组分。分离纯化的澳洲坚果抗菌活性多肽MPP⁃2含有DDLTDPAPA、VLL、WDY、VPV、WDL、LLW、LWL、FDW 8个肽段,经预测分析,属于抗菌肽的肽段为WDL与FDW,其概率得分a(1.00≥a≥0.50)均为1.00,疏水率均为66.67%,均带有1个负电荷,等电点分别为0.69与0.67,并具有较好的溶解性。研究结果表明澳洲坚果可通过酶法制备具有抗菌活性的肽类成分。

A Novel Polypeptide from Cervus elaphus Linnaeus

A novel polypeptide having stimulant effect on some cell proliferation was isolated from the velvet antler (Cervus elaphus Linnaeus). The velvet antler polypeptide consists of a single chain of 32 amino acid residues. Amino acid sequence of the polypeptide was identified as: VLSAADKSNVKAAWGKVGGNAPAFGAEALLRM.

A novel peptide from Apis mellifera and solid-phase synthesis of its analogue

A novel peptide designated secapin-1, was purified and characterized from Apis mellifera. The molecular weight of 25 amino acid peptide secapin-1 was found to be 2821.5625 Da by ESI-FTICR-MS. It showed high identity to secapin. The sequence of secapin-1 was determined to be YIINVPPRCPPGSKFVKNKCRVIVP by automatic Edman degradation. A disulfide bond was formed between Cys9 and Cys20 residues. In addition, an analogue of secapin-1 was synthesized by solid phase peptide synthesis method. The synthesis product was successfully purified and identified to homogeneity by using a combination of SEC, IEC, and RP-HPLC techniques.

紫苏粕蛋白抗氧化活性肽的制备、分离纯化及序列鉴定

以紫苏粕粉为原料,使用碱性蛋白酶进行水解反应,制备抗氧化活性肽。采用超滤离心、凝胶过滤色谱和反相色谱等分离纯化手段对其富集。结果表明,相较其它3种蛋白酶,碱性蛋白酶Alcalase对紫苏粕蛋白的水解程度最高,约为(25.94±0.21)%;碱性蛋白酶作用紫苏蛋白后的酶解产物的抗氧化活性最好,对DPPH自由基清除率约为(91.01±0.73)%。酶解上清液经超滤离心分离后最小分子质量组分F1(小于3 ku)抗氧化活性最强,F1组分经Sephadex G-25凝胶过滤色谱分离后按照分子质量大小依次得到P1、P2、P33个组分,其中分子质量最小的P3组分抗氧化活性最高。P3组分经反相色谱分离所得4个组分中,最后被洗脱出来的P3-4组分疏水性最强且DPPH·自由基清除率最高,质量浓度为3μg/mL的P3-4溶液的DPPH·清除率为(58.8±0.78)%。通过LC-MS-MS鉴定,抗氧化活性肽P3-4组分为十二肽,其氨基酸序列为Lys-Leu-Lys-Asp-Ser-Phe-Glu-Arg-Gln-Gly-Met-Val,分子质量为1437.8 u。本研究结果为深入开发紫苏蛋白资源,研发紫苏抗氧化活性肽提供理论参考。

Sequence Pattern Correlation of Amino Acid in Collision-induced Dissociation Electrospray Ionization Mass Spectrometry

A novel approach of sequence pattern correlation has been applied to predict an expected amino acid sequence from CID ESI MS spectra. The proposed approach deduces sequence patterns with no help from known protein database such that it is useful to identify an unknown peptide or new protein. The algorithm applies a cross correlation to match an experimental CID spectrum with predicted sequence pattern generated from fragmentation information. The fragmentation knowledge of both y series and other non y series are utilized to generate the predicted sequence patterns. In contrast to the normal de novo approach, the proposed approach is insensitive to mass tolerance and non susceptive to spectral integrality with no need for selection of a starting point.

蟹肉酶解物的鲜味物质分析及鲜味肽的鉴定

以中华绒螯蟹为研究对象,以水解度和感官评价为评价指标,采用木瓜蛋白酶、胰蛋白酶、复合风味酶、中性蛋白酶、碱性蛋白酶、胃蛋白酶对蟹肉进行酶解,利用氨基酸分析仪和高效液相色谱技术对酶解物中呈味物质进行分析,经分离纯化后采用高效液相色谱串联质谱技术鉴定酶解物中鲜味肽的氨基酸序列。结果表明,中华绒螯蟹蟹肉经胰蛋白酶酶解后,鲜味浓郁、感官评价最佳,其水解度为(51.99±1.85)%,其中鲜味肽、谷氨酸、5’-单磷酸肌苷(5’-inosine monophosphate,5’-IMP)和琥珀酸是主要鲜味物质,经质谱鉴定及鲜味预测筛选,得到14条分子量为795.42~981.55 Da的具有潜在鲜味特性的肽。

面筋蛋白咸味肽的分离纯化及结构鉴定

为了明确面筋蛋白酶解液中的咸味肽序列,对面筋蛋白咸味酶解物进行了分离纯化和结构鉴定。对酶解物脱盐处理后进行分离纯化。经过分级超滤,选择咸味最高、分子质量1 000 Da以下的组分进行葡聚糖凝胶Sephadex G-15过滤层析,结合感官评定结果筛选出咸味最强的组分,并利用液相色谱-串联质谱鉴定其氨基酸序列。最终得到面筋蛋白中咸味肽氨基酸序列为PFGQQ、PFSPQ、QPFP、PDFP、FDDP,分子质量分别为576.28、575.28、488.25、475.22、493.21 Da。本研究为面筋蛋白咸味肽的开发提供了一定理论依据。

蛙皮素抗菌肽Caerin 2.1的生物信息分析

文章旨在探究蛙皮素抗菌肽Caerin 2.1的生物学功能,利用在线生物信息学软件对蛙皮素抗菌肽Caerin 2.1的特性进行分析。结果显示,蛙皮素抗菌肽Caerin 2.1由25氨基酸组成,为阳离子型多肽,二级结构中主要包含α-螺旋和少量β结构及无规则卷曲,理论等电点为9.99,净电荷为+2,具有较好的稳定性,呈疏水性,为细胞内表达,具有3个磷酸化位点。研究表明,对蛙皮素抗菌肽Caerin 2.1的预测分析可为天然抗菌肽改造以获得稳定安全的抗生素替代品提供信息学基础。

5种鹿茸营养成分的主成分分析

对梅花鹿茸、马鹿茸、花马杂交鹿茸、麋鹿茸及驯鹿茸等五种鹿茸的常规成分、无机元素和氨基酸含量进行了测定。采用原子吸收光谱法测定了15种无机元素的含量;使用氨基酸分析仪结合分光光度法测定了五种鹿茸不同部位的17种氨基酸的含量。采用主成分分析法对鹿茸的营养成分进行分析,探讨了不同品种鹿茸的差异及特征成分。结果表明,粗蛋白、Ca、P、Na、Fe、Ba、Sr、谷氨酸及甘氨酸是鹿茸的特征成分,与鹿茸品质特征密切相关。根据无机元素含量的主成分分析得分图,可将梅花鹿茸、麋鹿茸与其他3种鹿茸区分,而常规成分和氨基酸的主成分得分图不能明显表征五种鹿茸的差异。主成分分析揭示了不同鹿茸在营养成分上的相似性和差异性。本研究为鹿茸的进一步开发利用提供了重要依据。

抗氧化肽的构效关系研究进展

综述了不同来源抗氧化肽的氨基酸组成、序列、可能的活性位点和抗氧化机制,以及目前主要的抗氧化肽构效关系研究方法。

马鹿茸不同分子量肽段中水解及游离氨基酸的含量分析

目的:测定马鹿茸不同分子量肽段中水解氨基酸和游离氨基酸的含量及构成。方法:采用柱前衍生化,氨基酸自动分析仪对马鹿茸肽段中氨基酸类成分进行含量测定。色谱柱为氨基酸分析专用ODS柱,柱温:27℃;检测波长360 nm;流动相总流速1.2 mL·min^(-1)。结果:马鹿茸肽段中氨基酸类成分线性关系良好,r均大于0.999;精密度、稳定性、重复性试验的RSD均小于3%;加样回收率在96.6%~104.7%之间,RSD值均小于2.4%。不同分子量肽段的氨基酸含量及构成有一定差异。50~100 k分子量段的氨基酸含量最高。结论:该方法简便可行、重复性好、准确度高,可用于马鹿茸药材多肽中水解氨基酸及游离氨基酸的含量测定。

ACE抑制肽构效关系研究进展

血管紧张素转化酶(angiotensin-converting enzyme,ACE)抑制肽是一类从食源性蛋白质中分离得到的具有降高血压活性的多肽。由于其降血压效果好,而且没有降压药物的毒副作用从而引起了广泛关注。近年来,ACE抑制肽的构效关系研究成为研究重点。结构生物信息学研究表明,ACE抑制肽的ACE抑制能力不仅与其分子质量有关,而且与其氨基酸序列以及其立体空间构象之间存在高度相关性。ACE抑制肽的抑制类型与ACE抑制活性、构效关系也存在一定相关性。对ACE抑制肽构效关系进行深入研究将有助于指导开发高活性的功能性食品及降血压药物。

梅花鹿鹿茸不同产品中氨基酸含量的比较

通过对二杠鹿茸、三杈鹿茸、鹿茸片、鹿茸血、鹿角、鹿角盘等鹿茸产品中氨基酸含量的测定研究,结果表明:鹿茸血中氨基酸含量最高,鹿茸片中的氨基酸含量次之,三杈鹿茸中的氨基酸含量高于二杠鹿茸中氨基酸含量,鹿花盘中的含量高于鹿角中的氨基酸含量,从而为鹿茸这一动物性中药材资源的功能评价、药理作用提供科学理论依据。

麋鹿茸样品的制备和化学成分分析

建立了麋鹿茸样品制备的工艺路线和方法 ,获得了易保存的干燥粉末样品 ,对麋鹿茸中的水分、粗蛋白、粗脂肪、膳食纤维、氨基酸、必需无机元素以及维生素的含量进行了测定 ,并与马鹿和梅花鹿茸进行了比较。结果表明 ,麋鹿茸与马鹿和梅花鹿茸的化学成分及含量相近 。

草鱼蛋白源抗氧化肽的分离及鉴定

利用超滤、离子交换色谱、高效逆流色谱以及凝胶过滤色谱等系列分离纯化技术从草鱼蛋白酶解产物中分离纯化抗氧化活性肽,分离过程中发现相对分子质量1～3kD的组分抗氧化活性最强,且碱性肽组分的抗氧化活性强于酸性或中性肽组分、疏水性肽组分的抗氧化活性强于亲水性肽组分。最终借助反相高效液相色谱在线连接的电喷雾质谱结合氨基酸分析鉴定出一种抗氧化肽,一级结构序列为Pro-Ser-Lys-Tyr-Glu-Pro-Phe-Val,相对分子质量为966.3D。