化学发光法对燕麦贮藏蛋白质抗氧化活性的评价

燕麦营养价值高,且蛋白含量丰富,球蛋白作为其主要的贮藏蛋白质,其必需氨基酸比例合理。目前,有很多燕麦蛋白加工方面的研究,而对于其生物活性的探讨较少。用三种化学发光体系对燕麦球蛋白和清蛋白的体外抗氧化能力进行研究,发现在清除超氧阴离子和保护DNA损伤方面球蛋白的效果优于清蛋白,其半数抑制率分别为0.85 mg/mL和7.3 mg/mL,而清蛋白有较好的清除羟基自由基的作用,其半数抑制率为2.26 mg/mL。结果说明,两种燕麦贮藏蛋白质有较弱的抗氧化活性。     

11S球蛋白水解产物功能特性及其对猪肉肠质构影响

以中豆36为原料,提取11S球蛋白,用菠萝蛋白酶对其水解,研究不同水解度酶解产物的持水性、吸油性、乳化性、乳化稳定性及疏水性等功能特性;结果表明,水解度为5%时11S球蛋白酶解产物吸油性、持水性、乳化活性最高;并将不同水解度酶解蛋白添加到猪肉肠中,水解度5%酶解蛋白可明显改善猪肉肠质构特性。     

Allergenicity of proteolytic hydrolysates of the soybean 11S globulin

ABSTRACT:  A substantial portion of the human population has immune hypersensitivities to various food materials. Soybean is one of the most common foods involved in such hypersensitivity reactions, especially in younger children. In this study, we investigated the effect of peptic and chymotryptic hydrolysis on the allergenicity of the 11S soybean globulin, which is the primary soybean allergen. The 11S globulin is composed of both acidic and basic polypeptides, and we found that the acidic polypeptide was effectively hydrolyzed, while basic polypeptide was more resistant to hydrolysis. The 11S globulin hydrolysate was size-fractionated by gel filtration, and 9 of the fractions obtained were tested for allergenicity against sera from 6 soybean-allergenic patients. The overall allergenicity of soybean 11S globulin was reduced by peptic and chymotryptic hydrolysis, although a gel filtration fraction with a major peptide of 20 kDa was highly immunoreactive. Hydrolyzed fragments of less than about 20 kDa were not immunoreactive.     

黑豆蛋白的分级提取及黑豆花色苷的成分鉴定

以黑豆为原料,添加不同浓度(0、5、10、15、20、25 mmol/L)的不同二价阳离子(Ca~(2+)、Mg~(2+)和Zn~(2+))分级提取黑豆蛋白,经冷冻干燥后用凯氏定氮法测得蛋白质量浓度,并对所得蛋白级分(7S、11S)的纯度和得率进行分析。结果表明,黑豆提取过程中所加入二价阳离子的类型及浓度显著影响7S和11S球蛋白的得率和纯度。利用综合平衡法,最终选定添加10 mmol/L的Mg2+分级提取黑豆球蛋白,得到7S蛋白纯度和得率分别为(86.29±3.25)%和(2.90±0.14)%,11S蛋白纯度和得率分别为(87.42±3.30)%和(9.11±0.28)%。用乙醇法提取黑豆花色苷,测得黑豆中总花色苷含量为(0.58±0.03)mg/g,总酚含量为(2.22±0.12)mg/g,对黑豆花色苷进行高效液相色谱-串联质谱分析,其组成成分为飞燕草色素-3-O-葡萄糖苷、矢车菊色素-3-O-葡萄糖苷、牵牛花色素-3-O-葡萄糖苷和锦葵花色素-3-O-葡萄糖苷。     

大豆11S球蛋白提取分离方法研究

以11S球蛋白粗提物中蛋白质含量和纯度为评价指标,比较了Nagano法、Saio法与Thanh法提取分离大豆11S球蛋白的效果,并对Thanh法提取分离大豆11S球蛋白的工艺参数进行了优化。结果表明,Thanh法提取分离大豆11S球蛋白效果较好,Tris-HC l缓冲液是适宜的提取液,最优提取工艺条件为提取时间2h、料液比1∶20、提取温度25℃。     

谷氨酰胺转胺酶对大豆7S蛋白质及肌球蛋白质胶凝性质的影响

大豆7S蛋白与肌球蛋白质经谷氨酰胺转胺酶（TGase）作用后,产物的十二烷基硫酸钠-聚丙烯酰胺凝胶电泳(SDS-PAGE)结果表明,两者均可在分子间生成共价键,形成相对分子质量较大的聚合物.10g/dL肌球蛋白质溶液加入10U/g的TGase,于35℃、pH7.0的条件下反应90min,体系的凝胶强度较对照组有了很大提高.10g/dL大豆分离蛋白质溶液与0.02U/mg的TGase在37℃下保温150min后,体系粘度增加了150mPa*s;而5g/dL的肌球蛋白质加酶并于10℃下保温180min后,其粘度值提高了600mPa*s.     

Anti-Thymocyte Globulin (ATG)-Free Nonmyeloablative Haploidentical PBSCT Plus Post-Transplantation Cyclophosphamide Is a Safe and Efficient Treatment Approach for Pediatric Acquired Aplastic Anemia

Most cases of acquired aplastic anemia (AA) arise from autoimmune destruction of hematopoietic stem and progenitor cells. Human leukocyte antigen (HLA)-haploidentical nonmyeloablative hematopoietic stem cell transplantation (HSCT) plus post-transplantation cyclophosphamide (PTCy) is increasingly applied to salvage AA using bone marrow as graft and anti-thymocyte globulin (ATG) in conditioning. Herein, we characterize a cohort of twelve AA patients clinically and molecularly, six who possessed other immunological disorders (including two also carrying germline SAMD9L mutations). Each patient with SAMD9L mutation also carried an AA-related rare BCORL1 variant or CTLA4 p.T17A GG genotype, respectively, and both presented short telomere lengths. Six of the ten patients analyzed harbored AA-risky HLA polymorphisms. All patients recovered upon non-HSCT (n = 4) or HSCT (n = 8) treatments. Six of the eight HSCT-treated patients were subjected to a modified PTCy-based regimen involving freshly prepared peripheral blood stem cells (PBSC) as graft and exclusion of ATG. All patients were engrafted between post-transplantation days +13 and +18 and quickly reverted to normal life, displaying a sustained complete hematologic response and an absence of graft-versus-host disease. These outcomes indicate most AA cases, including of the SAMD9L-inherited subtype, are immune-mediated and the modified PTCy-based regimen we present is efficient and safe for salvage.     

Characteristics of Seed Vigor in Rice Varieties with Different Globulin Accumulations

Seed vigor of rice is an important trait for direct seeding. The objective of this study was to reveal the relationship between globulin and seed vigor, and then to explore a method for evaluating seed vigor. Several rice varieties with different levels of 52 kDa globulin accumulation were used to compare seed vigor under normal and aged conditions. Results showed that varieties with high globulin accumulation obtained significantly higher seed vigor, measured by germination percentage and germination index, compared with those varieties with low globulin accumulation under normal and aged conditions. Meanwhile, a significantly higher accumulation of reactive oxygen species (ROS) was observed in the early germinating seeds of varieties with high globulin accumulation compared to those varieties with low globulin accumulation under normal and aged conditions. Collectively, the globulin content could be applied in the evaluation of seed vigor, which contributes to the selection of rice varieties for direct seeding.     

Oxidatively induced chemical changes and interactions of mixed myosin, β‐lactoglobulin and soy 7S globulin

The effects of oxidation on the chemical characteristics of myosin, β‐lactoglobulin and soy 7S globulin were investigated in a free radical‐generating system (FeCl₃/H₂O₂/ascorbate). Oxidised myosin exhibited a marked increase (>10‐fold) in carbonyls, a small increase in amines and conversion of some free sulphhydryls to disulphide bonds. Oxidised β‐lactoglobulin and 7S globulin also showed a major increase in the carbonyl content (five‐ and threefold respectively), but other chemical changes were relatively minor. In the oxidised myosin/β‐lactoglobulin composites, some cross‐linked aggregates were formed. Aggregation was also evidenced in the myosin/7S globulin composites exposed to the oxidising agents. The results indicated that oxidation enhanced interactions of the non‐muscle proteins with myosin apparently through the modification of amino acid side chains. These physicochemical changes may influence the functionality of processed muscle foods. © 2000 Society of Chemical Industry     

Effect of a microbial calcium‐independent transglutaminase on functional properties of a partially purified cowpea (vigna unguiculata) globulin

A partially purified globulin from cowpea seeds was polymerised by calcium‐independent microbial transglutaminase. The level of free amino groups in the globulin decreased with increase in enzyme concentration, suggesting that the cross‐linking reaction involved participation of the amino residues. At transglutaminase concentrations of 6–18 μg ml⁻¹ emulsifying activity decreased with increasing enzyme concentration and degree of cross‐linking, while a similar trend was observed for the foaming property at 6–12 μg ml⁻¹ transglutaminase concentrations. The resultant emulsions and foams formed by the cross‐linked proteins were more stable than those formed by the untreated protein. Sodium dodecyl sulphate polyacrylamide gel electrophoresis showed that of the two major polypeptides, the 55 kDa protein was more susceptible to transglutaminase action than the 50 kDa protein. Scanning electron microscopy revealed an amorphous structure for the control protein gel while a more defined and cross‐linked gel structure was observed for the protein treated with transglutaminase. The results suggest that protein products differing in functionalities can be obtained by controlling the degree of enzymatic protein cross‐linking. © 1999 Society of Chemical Industry