气溶胶单粒子的检测效率与基质辅助激光解吸电离研究

利用基质辅助激光解吸电离(MALDI)技术,在自行研制的气溶胶飞行时间质谱仪(ATOFMS)上实时探测单个生物气溶胶粒子的粒径和化学成分。采用双束激光空气动力学方法进行气溶胶粒子粒径的测量,并用266 nm的Nd∶YAG激光器对粒子进行激光解吸电离。以2,5-二羟基苯甲酸(DHB)和芥子酸为基质,对多肽生物样品进行了实验研究。质谱峰中质子化的分析物阳离子是在气相时,和基质通过质子转移反应形成的;而分析物碱金属加和物阳离子是在气相离子分子反应中,通过气相阳离子转移反应形成的。气溶胶粒子的检测效率为0.01%左右,命中率为10%左右。实验结果表明,该仪器可以满足大气中气溶胶单粒子的实时在线检测。     

Differences in the proteome profile in placenta from normal term and preeclamptic preterm pregnancies

The aim of this study was to use proteomic approaches to examine differences in protein expression in placentae from normal term and preterm preeclamptic pregnancies and to validate the data thus obtained by other independent methods. Using 2-DE we found that 80% of the proteins were present in both normal and preeclamptic placentae. However, 26 proteins in the normal term placentae were not matched in the preterm preeclamptic group. Six proteins showed increased intensity and one protein was down-regulated in preeclampsia. Four of the seven proteins that were altered in preeclampsia were further analyzed by Western blot and immunohistochemistry. Identification by MS techniques revealed these proteins to be involved in regulatory pathways activated by stress. This is significant because preeclampsia is a multisystem disorder in human pregnancies that results in considerable oxidative and nitrative stress. Three proteins identified by MS to be Hsp27, catalase, and glucose-regulated protein were confirmed by Western blot analysis to be significantly up-regulated in preeclampsia. Endothelial monocyte-activating polypeptide was shown to be down-regulated in preeclampsia by 2-DE and MS.     

肿瘤放射性受体显像剂奥曲肽的固相合成

采用苏氨酸转变为苏氨酸乙酯，再用LiAlH4还原该乙酯合成了苏氨醇，用自动多肽合成仪和Fmoc(9-芴甲基羰基)保护的氨基酸合成了7肽-树脂；再用三氟醋酸铊(Tl(Tfa)3)在7肽-树脂上形成7肽的二硫键；用苏氨醇氨解法裂解肽-树脂并在7肽链上接上苏氨醇形成八肽；然后用三氟乙酸脱去氨基酸侧链保护基团，用高效液相色谱法纯化八肽，得到了奥曲肽(OCT)。     

亚铁血红素肽复合型保护剂的性能

酶解牛血制取亚铁血红素肽,并于酶解底物及产物中分别添加不同种类亚铁保护剂,考察其对产物亚铁血红素肽的保护效果。结果表明,复合型保护剂的性能明显优于单一型。与空白组相比,酶解底物添加2∶1(抗氧化剂/还原剂质量比)的复合型保护剂可使亚铁含量提高24.5%;酶解产物中添加复合型保护剂后(2∶1),亚铁含量可提高37.7%。     

酶法水解豆粕制备多肽味素的研究

以豆粕为原料,通过多种酶的协同水解作用,制备一种新型的调味剂——多肽味素.研究了水解时间、酶制剂种类及添加量等因素对产物得率、水解蛋白得率及蛋白质水解度的影响.通过L9(34)正交实验得到最佳水解工艺条件:反应底物浓度为8%(以蛋白质质量计),水解时先添加0.10%的复合多糖酶水解1.5 h,水解pH为3.5,温度45℃;然后添加2%的复合蛋白酶、3%的风味蛋白酶,在温度55℃和pH7.0条件下,分别水解4 h,经灭酶、分离后可得到氨基酸态氮含量为0.546 g/100mL,蛋白质水解度为49.3%的水解液,再经浓缩、调配可制成多肽味素,其品质超过水解蛋白和普通酱油,接近酵母味素.水解蛋白得率为84.7%,水解产物得率为81.5%.     

Disaggregation of Islet Amyloid Polypeptide Fibrils as a Potential Anti-Fibrillation Mechanism of Tetrapeptide TNGQ

Islet amyloid polypeptide (IAPP) fibrillation has been commonly associated with the exacerbation of type 2 diabetes prognosis. Consequently, inhibition of IAPP fibrillation to minimize β-cell cytotoxicity is an important approach towards β-cell preservation and type 2 diabetes management. In this study, we identified three tetrapeptides, TNGQ, MANT, and YMSV, that inhibited IAPP fibrillation. Using thioflavin T (ThT) fluorescence assay, circular dichroism (CD) spectroscopy, dynamic light scattering (DLS), and molecular docking, we evaluated the potential anti-fibrillation mechanism of the tetrapeptides. ThT fluorescence kinetics and microscopy as well as transmission electron microscopy showed that TNGQ was the most effective inhibitor based on the absence of normal IAPP fibrillar morphology. CD spectroscopy showed that TNGQ maintained the α-helical conformation of monomeric IAPP, while DLS confirmed the presence of varying fibrillation species. Molecular docking showed that TNGQ and MANT interact with monomeric IAPP mainly by hydrogen bonding and electrostatic interaction, with TNGQ binding at IAPP surface compared to YMSV, which had the highest docking score, but interact mainly through hydrophobic interaction in IAPP core. The highly polar TNGQ was the most active and appeared to inhibit IAPP fibrillation by disaggregation of preformed IAPP fibrils. These findings indicate the potential of TNGQ in the development of peptide-based anti-fibrillation and antidiabetic nutraceuticals.     

Polypeptide Compositions and Antigenic Homologies Among Prolamins from Italian,Common and Japanese Millet Cultivars

Prolamins from Italian, common and Japanese millet cultivars were separately extracted with three kinds of alcohol (ethanol, propanol and isopropanol) and their component polypeptides and immunochemical relationships were examined by SDS-PAGE, two-dimensional electrophoresis and immunoblot analysis using the antiserum raised against Italian millet prolamin. Polypeptides of the individual millet prolamins appeared to be primarily composed of two major common subunit complexes with respective molecular masses ranging from about 19 to 23 kDa and from 13 to 14 kDa (groups A and B, respectively), although a few minor variations due to varietal differences were seen. Group A clearly contained one neutral subunit (21 kDa) and one basic one (22 kDa), while group B had one basic 14 kDa subunit. The Italian millet prolamin antiserum strongly bound with all three prolamin polypeptides but neither with the homologous non-prolamin fractions nor with the heterogeneous prolamins of the Triticeae (wheat, barley and rye). Amino acid compositions were found to be almost identical to one another.     

Cognitive impairments in the STOP null mouse model of schizophrenia.

Cognitive dysfunction is a primary and persisting core deficit of schizophrenia that is marginally improved by antipsychotic treatment. Adult mice that lack the stable tubule-only polypeptide (STOP) have neurochemical and behavioral abnormalities that model some features of schizophrenia. Recognition and long-term memory in the STOP null mouse were tested with the novel object recognition task and an olfactory discrimination task, respectively. Researchers examined the brains from STOP null mice to determine whether differences in task performance were associated with alterations in brain morphology. STOP null mice displayed deficits in both recognition and long-term memory. These behavioral deficits were accompanied by a massive enlargement of the cerebral ventricular system as well as by reductions in volume of cortical and diencephalic structures. In addition to deficits in recognition and long-term memory, STOP null mice displayed exaggerated neuroanatomical deficits somewhat reminiscent of those observed among individuals with schizophrenia. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

玉米皮蛋白多肽的组成与功能特性研究

本文对玉米皮蛋白多肽组成进行了分析，研究了它的功能特性，同时研究了pH值，离子浓度等因素对玉米皮蛋白多肽功能特性的影响。结果表明：玉米皮蛋白多肽具有较好的溶解性和乳化性，一定的起泡性、凝胶性以及较差的泡沫稳定性。