Relationship between gliadin peptide structure and their effect on the fetal chick duodenum

The tendency to form a beta-turn in alpha-gliadin was estimated using the B-cell determinant prediction program based on the Chou and Fasman probability of beta-turn formation. Six sequences possessing a high probability of beta-turn formation were found. A statistically high agreement was found between these six sequences and three areas in alpha-gliadin with the occurrence of Pro-Ser-Gln-Gln sequence which has recently been considered responsible for toxicity in coeliac disease. By means of solid-phase synthesis seven peptides were obtained covering the above-mentioned regions. Their toxicity was tested using the fetal chick duodenum. The results support the suggestion that peptides containing the sequences Pro-Ser-Gln-Gln and Gln-Gln-Gln-Pro may be involved in the pathogenesis of coeliac disease.     

Isolation and enzymatic fragmentation of the coeliac-active gliadin peptide CT-1

Summary Investigations on the structure/toxicity relationships of gliadin peptides were continued with the coeliac-active gliadin peptide CT-1, which is derived from the N-terminal portion (residues 3–24 of the amino acid sequence) of-gliadins [this journal (1986) 182:115–117]. CT-1 was produced by chymotryptic digestion and reversed-phase (RP) HPLC from the peptide fraction G3 [this journal (1992) 194:1–6] and digested with the proteases endoproteinase Glu-C, pancreatin, papain and thermolysin. The fragment peptids were separated by preparative RP-HPLC and characterized by amino acid analysis. On the basis of the specifity of the enzymes for CT-1 and the toxic effect of enzymatic hydrolysates of gliadin described in the literature, the significance of partial sequences, in particular of the sequence -Pro-Ser-Gln-Gln-Gln-Pro- for the coeliac-toxicity effect, is discussed.

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Isolierung und enzymatische Fragmentierung des coeliakieaktiven Gliadinpeptids CT-1

Zusammenfassung Die Untersuchungen über die Zusammenhänge zwischen der Struktur von Gliadinpeptiden und ihrer Toxizität wurden mit dem coeliakieaktiven Gliadinpeptid CT-1 fortgesetzt, das aus dem N-terminalen Bereich (Positionen 3–24 der Aminosäuresequenz) von-Gliadinen stammt [diese Zeitschrift (1986) 182:115–117]. CT-1 wurde aus der Peptidfraktion G3 [diese Zeitschrift (1992) 194:1–6] durch chymotryptische Partialhydrolyse und Umkehrphasen-HPLC gewonnen und mit den Proteasen Endoproteinase Glu-C, Pankreatin, Papain und Thermolysin umgesetzt. Die entstandenen Fragmentpeptide wurden durch präparative Umkehrphasen-HPLC getrennt und durch Aminosäurenanalyse charakterisiert. Anhand der Spezifität der Enzyme gegenüber CT-1 und der aus der Literatur bekannten toxischen Wirkung von enzymatischen Gliadinhydrolysaten wird die Bedeutung einzelner Sequenzabschnitte, insbesondere der Sequenz-Pro-Ser-Gln-Gln-Gln-Pro-, für die coeliakiespezifische Wirkung diskutiert.

     

Amino-acid sequence of the coeliac active gliadin peptide B 3142

Summary Peptide B 3142, which has been isolated from a peptic tryptic digest of whole gliadin by several separation steps [1], was examined for coeliac activity in an immunological test and in an organ-culture test, comparing enlarged groups of coeliac patients and control persons. In both test systems the peptide shows a coeliac specific effect.The N-terminal sequence analysis (EDMAN degradation), the C-terminal sequence analysis (incubation with carboxypeptidase Y) and the sequence determination of peptides, obtained from B 3142 by digestion with papain and chymotrypsin, result in the following total amino-acid sequence: H-Val-Pro-Val-Pro-Gln-Leu-Gln-Pro-Gln-Asn-Pro-Ser-Gln-Gln residues correspond to a molecular mass of 6,129 g/mol.

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Aminosäuresequenz des coeliakieaktiven Gliadinpeptids B 3142

Zusammenfassung Das in vorangegangenen Arbeiten [1] aus einem peptisch-tryptischen Partialhydrolysat von Gliadin über einen mehrstufigen Trennprozeß gewonnene Peptid B 3142 wurde an einem erweiterten Patientenkreis im immunologischen Test und im Organkultur-Test auf Coeliakie-Aktivität geprüft. In beiden Tests zeigt das Peptid eine Coeliakie-spezifische Wirkung. Die N-terminale Sequenzanalyse (EDMAN-Abbau), die C-terminale Sequenzanalyse (Umsetzung mit Carboxypeptidase Y) sowie die Sequenz-analyse von Spaltpeptiden aus den mit Papain und Chymotrypsin erhaltenen Partialhydrolysaten ergeben folgende, aus 53 Aminosäureresten bestehende Gesamtsequenz: H-Val-Pro-Val-Pro-Gln-Leu-GlnPro-Gln-Asn-Pro-Ser-Gln-Gln-Gln-Pro-Gln-Glu Gln-Val-Pro-Leu-Val-Gln-Gln-Gln-Gln-Phe-Pro-Gly-Gln-Gln-Gln-Pro-Phe-Pro-Pro-Gln-Gln-Pro-Tyr-Pro-Gln-Pro-Gln-Pro-Phe-Pro-Ser-Gln-Gln-Pro-Tyr-OH. Daraus errechnet sich eine Molmasse von 6129 g/mol.

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Supported by grants from Stiftung Volkswagenwerk and from Deutsche Forschungsgemeinschaft

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We gratefully acknowledge the excellent assistance given by Mrs. Schiltzler     

Isolation and enzymatic fragmentation of the coeliac-active gliadin peptide CT-1.

Investigations on the structure/toxicity relationships of gliadin peptides were continued with the coeliac-active gliadin peptide CT-1, which is derived from the N-terminal portion (residues 3-24 of the amino acid sequence) of alpha-gliadins [this journal (1986) 182:115-117]. CT-1 was produced by chymotryptic digestion and reversed-phase (RP) HPLC from the peptide fraction G3 [this journal (1992) 194:1-6] and digested with the proteases endoproteinase Glu-C, pancreatin, papain and thermolysin. The fragment peptides were separated by preparative RP-HPLC and characterized by amino acid analysis. On the basis of the specificity of the enzymes for CT-1 and the toxic effect of enzymatic hydrolysates of gliadin described in the literature, the significance of partial sequences, in particular of the sequence -Pro-Ser-Gln-Gln-Gln-Pro- for the coeliac-toxicity effect, is discussed.     

The effect of microwave treatment on the immunoreactivity of gliadin and wheat flour

Commercial gliadins and wheat flour were exposed to microwaves at power distribution of 70, 200, and 500 W for different time periods to achieve a level of applied energy doses up to 150 kJ. Ethanolic extracts (40 vol.% ethanol/water) of microwave treated samples were analyzed by ELISA with the use of either monoclonal antibodies against -gliadin or polyclonal anti-gliadin antibodies and by electrophoresis followed by immunoblotting. A significant increase in reactivity, almost 210% over the untreated control sample, was observed for gliadins exposed to the energy dose of 40 kJ. Gliadins treated with higher energy doses showed a drop in an immune response independent of monoclonal or polyclonal antibodies used in ELISA. Gliadin fractions extracted from wheat flour treated with microwaves demonstrated similar immunoreactivity changes vs applied energy, although the maximum of reactivity appeared at 30 kJ. The increase in immune response of microwave irradiated gliadins was also confirmed by immunoblotting assay with the use of sera of patients susceptible to wheat flour allergy. Reversed phase HPLC elution profiles of treated gliadins showed that the content of all gliadin fractions in microwave treated samples decreased with the increase of the dose of applied energy.     

Relationship between the colour and the chemical structure of carotenoid pigments

Several carotenoids were isolated and their colours were ascertained objectively to establish relationships between the chemical structures of those pigments and their actual colours, considering the coordinates of the uniform space CIELAB. The results of this study revealed that the different carotenoids surveyed could be grouped in the a^∗b^∗ plane according to the number of conjugated double bonds. For yellowish carotenoids, it was observed that a^∗ values clearly decreased from those with 11 conjugated double bonds (c.d.b.) to those with 9 c.d.b., although this trend reversed in the case of carotenoids with 7 c.d.b.. In terms of hue (h_ab), it was seen that the decrease in conjugation of the molecules involved a slight rise in h_ab. On the other hand, the aperture of the end rings or the increase in conjugation involved clear increases in hue.     

活性染料的结构与盐感度的关系

活性染料的结构与其染色盐感度之间有着密切的关系。研究表明，一般情况下，活性染料的染色盐效应随着活性染料荷质比的增大而增强，但染料分子量过大或过小时例外。     

OPTIM形态尺寸记忆性与其结构之间的关系

OPTIM纤维细化过程中,由于分子中二硫键-S-S-的记忆性、拉伸时的内应力及塑性变形的变化,使OPTIM与原毛、羊绒相比,纤维弹性回复率、缩绒性减小;湿润胀性、松弛收缩率增大,纤维形态记忆性降低.文章分析了OPTIM大分子结构、超分子结构及形态结构变化与织物形态记忆性的关系,提出了提高OPTIM纤维及织物形态尺寸记忆性的措施.     

精纺毛织物抗皱性能与织物结构参数的关系

采用相同的后整理工艺,研究了原料细度、捻系数、织物总紧度和纬经比对毛织物抗皱性能的影响。结果表明,纤维越细,织物抗皱性能越好;降低经纱捻系数或增加纬纱捻系数,均可提升织物的抗皱性能;组织结构不同,织物总紧度和纬经比对抗皱性能的影响程度也不尽相同。     

大豆肽分子量与缓解疲劳作用关系的研究

为了研究大豆肽分子量与缓解疲劳作用的关系,分别给小鼠灌胃不同分子量的大豆肽,然后测定缓解疲劳指标,包括体重、游泳时间、血清尿素氮含量、肝糖原含量和血乳酸含量。试验结果表明,大豆肽对小鼠体重变化影响不显著,但是游泳时间延长,血清尿素氮含量降低,肝糖原含量提高,血乳酸含量降低。其中相对分子质量为875和500的大豆肽对缓解疲劳指标影响显著。大豆肽分子量越小,缓解疲劳作用效果越明显。     

薄型精纺毛织物刚柔性与织物结构参数的关系

以14种精纺薄型毛织物为例,采用斜面悬臂法测定织物的经向和纬向抗弯长度,根据试验数据分析原料和织物组织对织物刚柔性的影响,并运用Origin7.0分析纱线的捻度、线密度,织物的厚度、经密和纬密与织物刚柔性的关系。分析得出:织物刚柔性与构成织物原料的性能、纱线的结构和织物结构有很大的关系。原料的初始模量越小,织物的柔软度越好;纱线的捻度越大,织物的柔软度越差,纱线的线密度越大,织物呈现刚性;平纹组织的刚性大于斜纹组织,织物越厚,织物越呈现刚性,在其他参数相同的情况下,织物经、纬密增加时,织物的抗弯长度增大,织物越呈现刚性。     

冻藏时间对麦谷蛋白和麦醇溶蛋白二级结构及面团性能的影响研究

分别对小麦醇溶蛋白和麦谷蛋白在-18℃下冻藏0²8d后其巯基和二硫键含量以及二级结构的变化情况进行研究,并分析了变化可能的内在机理;进一步探讨了冻藏导致的面团质构变化与两种面筋蛋白结构变化的对应关系。结果表明:冻藏处理使麦醇溶蛋白和麦谷蛋白中巯基含量增加、二硫键含量减少,α-螺旋和β-转角结构含量下降,β-折叠结构含量升高;其中,冻藏处理对麦谷蛋白二级结构的影响程度要明显大于麦醇溶蛋白。质构研究结果表明:两种蛋白质中二硫键、α-螺旋和β-转角结构含量的减少,对冻藏后面团粘性、弹性、硬度的降低有着重要影响。      

马来酸酐-丙烯酸共聚物结构与皂洗性能的关系

合成了不同结构的马来酸酐-丙烯酸共聚物,并探讨了单体共聚比例对共聚物螯合分散性能和皂洗性能的影响。实验结果表明,单体质量比为15:25的马来酸酐-丙烯酸共聚物具有较好的螯合分散性能和皂洗性能;将其与增效剂复配制得的酸性皂洗剂,应用于棉针织物活性染料染色后的皂洗,不影响染色织物的K/S值及颜色鲜艳度,皂洗后织物的色牢度与常规皂洗工艺相当,而且可以省去酸中和工序,节能节水。     

长碳链聚合物材料的结构与固色性能研究

在既有季铵盐结构又有反应性基团的高聚物树脂中引入长碳链侧链端基 ,将长碳链化合物与丙烯类单体共聚 ;研究了不同长度的碳链端基结构对活性染料固色性能的影响。结果表明 :不同长度的碳链结构对聚合物的成膜性、固色性能和手感都有明显改善 ,第三单体的碳链越长 ,所得聚合物固色性能越好 ,固色后织物柔软性能越好     

小麦醇溶蛋白高频谱带与品质性状的相关性分析

利用A-PAGE技术,分析了20个小麦品种（系）醇溶蛋白的等位变异,共检测出51条迁移率不同的谱带,其中带Gli-16.5,Gli-19.1,Gli-23.2,Gli-31.4,Gli-34.8,Gli-36.6,Gli-46.2,Gli-55.3,Gli-58.6,Gli-63.0,Gli-69.4出现频率高于50%,为高频谱带。结合凝胶成像系统,分析这些高频谱带与小麦品质性状之间的关系,结果表明：Gli-19.1与湿面筋和蛋白质含量呈显著正相关,Gli-63.0与湿面筋呈极显著正相关,Gli-16.5、Gli-58.6、 Gli-69.4与沉降值呈显著或极显著正相关。Gli-31.4与蛋白含量和湿面筋呈显著或极显著负相关, Gli-34.8 与沉降值呈显著负相关,Gli-36.6与蛋白质含量、湿面筋、沉降值呈显著或极显著负相关。因此认为Gli-19.1属于优质带,而Gli-36.6,Gli-31.4属于劣质带,这些带可以作为生化标记用于优质小麦的辅助选择。     

毛织物的服用性能与纱线和织物结构的关系

文章从手感、折皱恢复性、尺寸稳定性、起球、耐磨性、断裂强度等几方面论述了毛织物的服用性能与纱线和织物结构的关系,并指出毛织物设计中应注意的问题,为纺织技术人员提供有参考价值的理论指导.     

精纺毛织物结构参数与折皱回复性的关系

为探究精纺毛织物结构参数与折皱性能的关系,收集了18 种精纺毛织物,应用JN-1型织物折皱回复性能动态测试仪进行折皱回复角测试,通过数据分析,得出结构参数与折皱回复角间的关系。为了进一步分析各结构参数对织物抗皱性能的影响程度,找出对折皱回复角影响较大的结构参数,同时研究了织物结构参数与折皱回复角的相关性。结果表明：精纺毛织物的折皱回复性不仅与织物原料、纱线线密度和捻度有关,还与织物经纬密、织物紧度以及面密度有关;除了纤维原料以外,纱线捻度对织物折皱回复性的影响最为显著。     

大豆蛋白水解度与大豆肽抗氧化力关系研究

通过研究酶解大豆蛋白的水解度与大豆肽的抗氧化力大小,探索大豆蛋白水解度与大豆肽抗氧化力的关系。结果表明,两种组合蛋白酶所水解大豆蛋白的水解度大于其中任一种蛋白酶的水解度,小于两种蛋白酶的水解度之和;组合蛋白酶制备的大豆肽抗氧化力也大于其中任一种蛋白酶制备的大豆肽抗氧化力,小于两种蛋白酶制备的大豆肽抗氧化力之和;大豆肽抗氧化力的大小和大豆蛋白的水解度、单一蛋白酶及组合蛋白酶的种类有关,大豆肽抗氧化力有最佳水解度范围（18%~19%）,大豆蛋白水解度过大或过小时,大豆肽抗氧化力都会下降。     

蓝圆鲹抗氧化肽与其他抗氧化剂的协同效应的研究

以DPPH·和O₂^-·清除率为指标,探讨了蓝圆鲹多肽（RSH-III）分别与其他肽类抗氧化剂GSH和非肽类抗氧化剂vitamin C的协同抗氧化效应。研究结果表明,当清除DPPH自由基时,低浓度条件下的RSH-III(0.2、0.4 g·L^-1)分别与GSH(1.0×10-3、2.0×10-3g·L^-1)和vitamin C(0.7×10-3g·L^-1)复合时未表现出协同效应;较高浓度(0.8 g·L^-1)时表现出负协同作用。当清除O₂^-·自由基时,RSH-III与低浓度GSH(1.3×10-3g·L^-1)复合时未表现出协同效应,较高浓度(2.5×10-3⁴.2×10-3g·L^-1)时表现出负协同作用;而与vitamin C复合清除O₂^-·自由基的清除率与抗氧化剂的添加浓度无关,均表现出负协同效应。该研究为蓝圆鲹抗氧化活性肽的应用奠定了较好的基础,可用于指导抗氧化活性肽的高效应用。