乳清分离蛋白酶解物的抗氧化活性研究

研究了乳清分离蛋白(WPI)酶解物对DPPH.、超氧阴离子自由基和羟基自由基的清除效果,同时用还原法研究了其抗氧化活性。结果表明,WPI酶解物在体外具有较强的抗氧化能力。木瓜蛋白酶酶解物和胰蛋白酶酶解物对DPPH.、超氧阴离子自由基、羟基自由基的清除能力和还原能力强于胰凝乳蛋白酶酶解物和胃蛋白酶酶解物。     

一组特异存在于猪乳中的高分子量蛋白质

猪乳中含有多种蛋白质,介绍了猪乳中新发现的一组高分子量蛋白质的研究现状,对其生化性质和功能作了综述,并探讨对其进一步研究和开发的重要意义。     

猪乳中一高分子量蛋白质的分离纯化和鉴定

对猪乳中一高分子量蛋白(HMWP)进行了分离纯化,并对其某些生化性质进行了鉴定。猪乳通过去脂得到脱脂乳,再去除酪蛋白得到乳清。对乳清进行硫酸铵分级盐析,猪乳中HMWP在40％饱和度硫酸铵盐析下有最大沉淀。收集40％饱和度硫酸铵盐析沉淀,经过溶解、透析得到HMWP的粗品。通过Mono Q离子交换柱,对其粗品进行两次层析提纯,得到了HMWP纯品,其纯度和得率分别为97．85％和12．31％。多种植物凝集素的Western blotting鉴定表明,HMWP是一个糖基种类较少的糖蛋白,含有Man和GlcNAc。SDS-PAGE和凝胶过滤分别测得HMWP的分子量为114．8kD和115．0kD。通过等电点测定,HMWP的pI为5．10。HMWP的氨基酸组分分析得知,其富含Asp、Glu、Gly和Cys,疏水性氨基酸较低,仅占15．59％摩尔分数。这些结果说明HMWP是一个易溶于水的、酸性的分泌性单体球蛋白。N端氨基酸序列测定结果为Ala-Leu-Val—Gln-Ser-Gty-Leu-Ash-Leu-Val,通过从网络Genbank检索没有发现其同源蛋白的序列,说明其可能是一个新蛋白。     

高乳清蛋白的肠内营养对大鼠伤口愈合的影响

探讨高乳清蛋白的肠内营养对大鼠创伤皮肤的促愈合作用.将36只SD大鼠随机分为3组,每组12只,即高乳清蛋白肠内营养组(A)、普通肠内营养组(B)、空白对照组(C),建立大鼠皮肤创伤模型后进行肠内营养支持,肠内营养用量为每天731.5kJ·kg-1,以灌胃的方式提供,分别于术后第7、14天测定血清蛋白、血红蛋白含量并计算创面愈合率.结果显示,术后第7、14天A组的血清蛋白、血红蛋白及伤口皮肤平均愈合率显著高于B、C组,差异具有统计学意义(p＜0.05).表明高乳清蛋白肠内营养具有较好的促进伤口愈合的作用.     

Protective Effect of Administration of Skim Milk on Exogenous and Endogenous Infection in Mice

In order to minimize the denaturation of proteins in milk, normal cow's milk was pasteurized at 61 C for 20 min. The protective effects of the thus prepared skim milk (low-heat skim milk) on exogenous and endogenous infection were examined as compared with conventional skim milk which was pasteurized at 121 C for 2 sec. The antibody titers to Listeria monocytogenes and Escherichia coli of low-heat skim milk were almost equal to that of raw milk, while no antibody was detected in the conventional skim milk. When mice were given low-heat skim milk or conventional skim milk, the incidence of the translocation of orally inoculated Listeria monocytogenes to the spleen was lower in the low-heat skim milk group than that in the conventional skim milk group. The life span of 7 Gy X-ray irradiated mice given low-heat skim milk was significantly prolonged in comparison to that of mice given conventional skim milk. However, there were no differences in the number of bacteria in the feces or IgA production by Peyer's patch cells between the two groups. These results suggest that antibodies in low-heat skim milk, which still have reactivity to exogenous or indigenous bacteria, may contribute to the protective effects against bacterial infection.     

猪乳中一组高分子量蛋白的多态性与乳生长因子、窝增重的关系

利用十二烷基硫酸钠-聚丙烯酰胺凝胶不连续垂直板电泳(SDS-PAGE),对162头二花脸母猪乳中一组高分子量蛋白质(HMWP)进行了检测和分型,并运用线型模型统计分析方法分析了该基因座的不同基因型与母猪的乳生长因子(IGF-1、EGF和胰岛素)、哺乳仔猪生长(20日龄窝增重)的关系.结果表明,在三种HMWP基因型中,不同基因型母猪的乳中IGF-1浓度存在显著差异,HMWP基因型为BB型和BD型的母猪,其乳IGF-1浓度均高于DD型,其中BB型显著高于DD型(P＜0.05).乳中胰岛素浓度也存在差异的趋势,但未达到显著水平(P＞0.05),BB型和BD型母猪的乳中胰岛素浓度高于DD型.HMWP基因座不同基因型的乳EGF浓度无显著差异(P＞0.05).在三种HMWP基因型中,不同基因型母猪的20日龄窝增重存在显著差异,HMWP基因座为BB型和BD型的母猪,其20日龄窝增重均高于DD型,其中BD型显著高于DD型(P＜0.05).实验结果提示,HMWP多态性可能作为一个潜在的遗传标记应用于猪的遗传育种.     

HPLC法分析乳清蛋白对糖尿病模型小鼠血浆氨基酸组分的影响

为寻求有效的氨基酸分离方法并探讨乳清蛋白对2型糖尿病防治的作用机制,采用HPLC法分析乳清蛋白中氨基酸组分及含量;分别以0％、10％、20％和40％的乳清蛋白(WP)灌胃1型、2型糖尿病模型组、正常组小鼠,4周后观察各组血浆氨基酸的变化.乳清蛋白中亮氨酸、异亮氨酸、缬氨酸分别占氨基酸总量的14.40％、5.93％和5....     

乳清蛋白质制剂改善慢性肾功能衰竭透析患者营养状况的效果观察

目的用乳清蛋白质制剂作为蛋白质补充营养制剂,观察其对慢性肾功能衰竭透析患者营养改善的效果。方法 60例接受透析治疗的慢性肾功能衰竭患者,平均年龄(59.3±6.7)岁,随机分为试验组和对照组,每组30例。试验组每天除常规饮食外,按0.6g/kg补充乳清蛋白质制剂,共15 d,对照组为正常治疗饮食。在干预前、后分别检测营养相关的指标。结果根据身高和体重进行营养评价,干预开始前试验组、对照组的患者均有不同程度营养不良,15 d后体重与干预前相比,虽有所改善,但无显著性差异(P>0.05)。体重、上臂肌围、三头肌皮褶厚度在干预后变化均不明显,无显著性差异(P>0.05)。血红蛋白有所升高,但无统计学意义(P>0.05)。干预前后,试验组血清白蛋白、前白蛋白均有升高,前白蛋白与对照组相比有显著性差异(P<0.05)。干预后试验组血清磷与对照组比较无显著性差异(P>0.05)。试验组和对照组血清尿素氮、肌酐在干预后,均降低非常显著(P<0.05)。干预前患者血清氨基酸,特别是必需氨基酸和组氨酸含量降低明显(P<0.05),用乳清蛋白质制剂后血清氨基酸谱有所变化,支链氨基酸-亮氨酸、异亮氨酸和缬氨酸含量明显增高,苏氨酸、酪氨酸、组氨酸也有所升高,其余氨基酸血清含量无明显改变。结论乳清蛋白质制剂对慢性肾功能衰竭透析患者有明显的改善蛋白质营养状况的效果。     

乳清蛋白在运动营养中的功能特性和作用

乳清蛋白是牛乳中一类营养价值较高的优质蛋白,必需氨基酸种类齐全,组成模式与人体相似,并含有丰富的支链氨基酸和多种生物活性物质,能够提高机体的抗氧化能力,增强机体免疫力,促进骨骼肌蛋白质的合成,抑制肌肉蛋白分解,加速训练后体能的恢复,对于运动人群而言,是补充优质蛋白的良好来源.本文就合理的补充乳清蛋白对缓解运动性疲劳、提高运动能力的研究进展进行了综述.     

饲喂雌鼠大豆异黄酮对后代雌性生殖性状的影响

目的研究雌性小鼠饲喂异黄酮后对其后代雌鼠生殖性状的影响。方法分别在雌鼠从断奶到妊娠前和妊娠期间两个不同阶段的日粮中添加不同剂量的大豆异黄酮（0、50、400 mg/kg）。记录F1代的出生窝产仔数、出生窝重、雌鼠的阴道最早开张时间和最早见栓时间,以及后代雌鼠性成熟期和体成熟期生殖器官重量、血清雌激素的含量。结果雌鼠妊娠期饲喂含50、400 mg/kg大豆异黄酮的饲料后F1代的窝产仔数显著高于对照组（P〈0.05）;雌鼠妊娠期采食400 mg/kg大豆异黄酮饲料,其后代雌鼠初次配种时间明显延迟（P〈0.05）;45、65日龄体重显著低于对照组,65日龄子宫重显著低于对照组,卵巢重显著高于对照组;血清中雌激素含量显著低于对照组（P〈0.05）,妊娠期间采食50 mg/kg大豆异黄酮饲料,其F1代雌鼠仅窝产仔数和45日龄时血清中雌激素含量受到影响;而雌鼠从断奶到怀孕期间饲喂含大豆异黄酮饲料的F1代在各项指标与对照组均差异无显著性。结论雌鼠妊娠期间饲喂含400 mg/kg大豆异黄酮的饲料会显著影响其雌性后代的初情期、生殖器官发育、血清雌激素含量等生殖生理性状,而在非妊娠期饲喂含大豆异黄酮饲料对F1代无显著影响。     

Development of Transgenic Mice Expressing Calcitonin as a Beta-lactoglobulin Fusion Protein in Mammary Gland

Expression of foreign proteins in mammalian milk is becoming a widespread strategy for high-level production of recombinant pharmaceuticals, especially those with the most complex post-translational modifications. A milk-specific ovine beta-lactoglobulin (oBLG) promoter was used to drive expression of recombinant calcitonin in mouse milk. A gene construct was generated, consisting of 10.7 kbp of the oBLG gene including its promoter and 3′ flanking region with the calcitonin coding sequences inserted in-frame into the oBLG fifth exon. After microinjection, six founder mice transmitted the transgene to their progeny. RT-PCR confirmed mammary-gland specific expression of recombinant mRNA in most transgenic mice and Western blot analysis confirmed expression of chimeric protein. Calcitonin can thus be expressed under the oBLG promoter and regulatory elements in a mammary-gland specific manner.     

黄鳍金枪鱼头蛋白酶解液对小鼠免疫功能的调节作用

以金枪鱼头为原料,经酶解得到蛋白酶解液;以环磷酰胺造小鼠免疫功能低下模型,同时灌胃金枪鱼头蛋白酶解液,观察小鼠免疫脏器指数,巨噬细胞吞噬功能,ConA刺激的淋巴细胞增殖和溶血空斑细胞形成能力。结果显示金枪鱼头蛋白酶解液能显著增强免疫抑制状态下的小鼠腹腔巨噬细胞吞噬能力和胸腺、脾脏指数;明显提高免疫抑制状态小鼠的脾淋巴细胞转化能力及抗体细胞形成能力。说明金枪鱼头蛋白酶解液对环磷酰胺造成的免疫功能低下小鼠的非特异性免疫和特异性免疫功能都有正向调节作用。     

脂肪细胞型脂肪酸结合蛋白疫苗对高脂喂养雌鼠体重和糖耐量的影响

目的:构建能诱导出针对脂肪细胞型脂肪酸结合蛋白(FABP4)特异性中和抗体的疫苗,为高脂诱导下肥胖和胰岛素抵抗的防治新途径提供理论和实验依据。方法:野生型C57BL/6J雌鼠随机分为疫苗组(n=10,高脂饲养)、佐剂组(n=10,高脂饲养)和空白对照组(n=10,普通饲养),分别予以皮下注射生物合成的FABP4蛋白、佐剂和磷酸盐缓冲液,观察比较各组抗体滴度、安全耐受性和体重、摄食量、空腹血糖、胰岛素抵抗指数(HOMA-IR)、糖耐量实验血糖曲线下面积(AUC)等指标。结果:疫苗组小鼠产生了高滴度的FABP4特异性抗体,并于第3轮加强免疫后达到平衡状态。首次免疫16周后,疫苗组小鼠体重高于空白对照组,但明显低于佐剂组(P<0.05);日平均摄食量高于空白对照组(P<0.05),与佐剂组无差异(P>0.05);空腹血糖、HOMA-IR、腹腔葡萄糖耐量实验AUC均明显低于佐剂组(P<0.05),与对照组无统计学差异(P>0.05)。结论:以FABP4作为抗原免疫小鼠,可产生高滴度特异性抗体IgG,有效降低高脂喂养野生型雌性小鼠体重、空腹血糖、HOMA-IR和血糖AUC等指标,为高脂诱导的肥胖和胰岛素抵抗的治疗提供了新的途径和初步证据,可进行深入研究。     

Consumption of Soy Protein Isolate Reduces Hepatic SREBP-1c and Lipogenic Gene Expression in Wild-Type Mice,but Not in FXR-Deficient Mice

We examined to determine whether hepatic gene expression is affected in mice in which blood lipid levels remain unchanged fed soy protein isolate (SPI) for a short time. We also examined SPI-mediated effects in farnesoid X receptor (FXR)-deficient mice. Compared with casein, SPI affected the expression of various hepatic genes related to lipid metabolism in the wild-type mice. No effects of SPI were observed in the FXR-deficient mice, suggesting the importance of FXR. Hepatic peroxisome proliferator-activated receptor γ coactivator 1α (PGC-1α) gene expression was reduced by SPI, and this might be associated with a decrease in FXR expression. Decreased FXR led to decreased expression of its target, the bile-salt export pump necessary for bile acid secretion and dietary lipid absorption. The earliest response to SPI was a decrease in hepatic sterol regulatory element-binding protein (SREBP)-1c mRNA, on day 3. SPI activated hepatic adenosine monophosphate-activated protein kinase (AMPK), which can lead to a reduction in SREBP-1c mRNA. These data indicate the importance of SREBP-1c and PGC-1α/FXR in SPI-mediated alterations in hepatic gene expression.     

黄连素对肥胖小鼠肠道菌群的影响及其机制

为了探索黄连素对肥胖小鼠肠道菌群的影响和作用机制,本研究将40只雄性昆明种小鼠随机分为空白组、模型组、黄连素高剂量组、黄连素中剂量组和黄连素低剂量组,每组8只,除空白组外,其余4组给予高脂饮食,建立实验性肥胖小鼠模型。造模14 d后,全部给予正常饮食,黄连素高、中、低剂量组灌胃给予每天0.1～0.3 mL/10 g的药物干预,空白组和模型组给予等剂量的生理盐水,给药持续14 d。每周称量两次体质量,并分别于实验第0、14、28天从眼眶取血测定血脂和炎性因子的含量,收集小鼠粪便测定乳酸杆菌和双歧杆菌的数量。研究结果表明:空白组和模型组小鼠的体质量在第14天时有明显差异,造模成功;实验第28天,黄连素各给药组小鼠的体质量与模型组相比有显著性差异。模型组双歧杆菌、乳酸菌的数量和血脂水平与空白组比较有显著性差异,黄连素给药组能显著改善肥胖小鼠的血脂水平和双歧杆菌、乳酸杆菌的数量。本研究结果初步得出结论认为:黄连素改善肥胖小鼠的作用机制可能与脂质代谢、炎性反应和肠道微环境的改变密切相关。     

Stronger Suppression of Plasma Cholesterol and Enhancement of the Fecal Excretion of Steroids by a Buckwheat Protein Product than by a Soy Protein Isolate in Rats Fed on a Cholesterol-free Diet

We investigated the effects of a buckwheat protein product (BWP), soy protein isolate (SPI) and casein on the plasma cholesterol level and fecal steroid excretion in rats fed on a cholesterol-free diet. The consumption of BWP suppressed plasma cholesterol by enhancing the fecal excretion of both neutral and acidic steroids. These effects of BWP were stronger than those of SPI.     

小鼠脊髓重与颈膨大截面积QTL研究

应用近交系小鼠A/J和C5 7BL/ 6J以及其F2 代重组小鼠定位脊髓重与颈膨大截面积数量性状基因座(QuantitativeTraitLoci,QTL)。结果表明 13个QTL与脊髓重和截面积相关 ,这些QTL分别位于 2、4、8、14、15、17、18、19和X染色体上。其中 6个QTL与脊髓重相关 ;4个QTL与颈膨大截面积相关 ;3个QTL与二者均相关。在 13个QTL中 ,3个QTL (P <0 0 1)———SC1(位于D15Mit15 8附近 )、SC2 (DXMit14 0附近 )和SC3(DXMit6 4附近 )其表型变异的解释率分别为 2 4 %、19%和 15 % ;加性效应分别为 - 3 78、3 4 1和 2 0 6mg。其他QTL的P值在 0 0 1～ 0 0 5之间。在上述 3个QTL中 ,SC1是唯一与脊髓重和面积均相关的QTL     

Hypoglycemic Effect of a Hot-water Extract from Defatted Sesame (Sesamum indicum L.) Seed on the Blood Glucose Level in Genetically Diabetic KK-Ay Mice

Genetically diabetic (type II) KK-A^y mice, male and 5 weeks of age, were divided into one group of 12 mice that were fed on a basal (BAS) diet and three groups of 6 mice each that were fed on the test diets for 4 weeks. Each test diet contained 4.0% of the hot-water extract (HES) from defatted sesame (Sesamum indicum L.) seed, 1.4% of the water eluent fraction (WFH) of HES or 0.7% of the methanol eluent fraction (MFH) of HES from a glass column packed with HP-20 resin. At the end of the feeding period, the BAS group was divided into the MAL and MALH groups which were respectively force-fed with 1 ml per mouse of a 20% maltose solution in water with or without 4.0% HES. The plasma glucose concentration and amount of urinary excreted glucose were lower from the HES and MFH diets than from the BAS and WFH diets. The levels of plasma glucose and serum insulin were lower in the MALH group than in the MAL group. These results indicate that HES and MFH had a reductive effect on the plasma glucose concentration of KK-A^y mice, and this effect is suggested to have been caused by the delayed glucose absorption.     

草地藏系绵羊乳游离氨基酸质量分数及蛋白遗传多态性研究

用反相高效液相色谱法检测草地藏系绵羊乳游离氨基酸质量分数,用聚丙烯酰胺凝胶电泳法研究乳蛋白组分及其遗传多态性。结果表明:草地藏系绵羊乳中检测到17种游离氨基酸,其中质量分数最高的为Arg;与金堂黑山羊乳比较17种游离氨基酸中,甲硫氨酸的质量分数极显著高于金堂黑山羊(p<0.01),而天冬氨酸、甘氨酸、赖氨酸、谷氨酸、苏氨酸、丙氨酸和缬氨酸的质量分数均显著低于金堂黑山羊(p<0.05),其余9种游离氨基酸质量分数未发现明显差异,但两种羊乳中的必需氨基酸总量基本相同,差异不明显(p>0.05)。草地藏系绵羊乳蛋白组分主要包括α-La、β-Lg、CN、IgG等,CN的相对质量分数约50%~52%;研究还发现4种分子量类型的乳上皮粘蛋白MUC1,分子量分别为214kD、209kD、207kD、205kD;CN、β-Lg均未检测到多态性,说明草地藏系绵羊乳蛋白遗传多态性较为贫乏。     

Recombinant Human Protein C Expression in the Milk of Transgenic Pigs and the Effect on Endogenous Milk Immunoglobulin and Transferrin Levels

Colostrum and milk are natural vehicles for acquiring passive immunity and are valuable tools for decreasing neonatant mortality from diarrheal disease. The effects of recombinant human protein C (rhPC) expression levels on endogenous immunoglobulin and transferrin content of the milk of different lineages of transgenic pigs were studied. The levels of rhPC in the milk ranged from 40 to 1200g/ml. Transgenic pigs with rhPC expression levels less than 500g/ml had no significant differences in milk protein composition with respect to nontransgenic pigs. A line of transgenic pigs having rhPC expression levels of 960–1200g/ml had two- to three-fold higher IgG, IgM, and secretory IgA concentrations compared to other transgenic and nontransgenic pig groups (P<0.05), and four- to five-fold higher transferrin levels than nontransgenic pigs (P<0.05). Changes in milk protein composition were not associated with mastitis or other pathologic disruption of epithelial cell junctions as indicated by normal casein and albumin levels in milk. Since IgG, IgM, secretory IgA, and transferrin are transported into the milk by transcytosis, higher levels of these proteins indicate that transcyctosis in the mammary epithelial cell was likely upregulated in pigs having high rhPC expression levels. This study is the first that shows a statistically significant example that mammary tissue specific expression of a heterologous protein can enhance endogenous phenotypic characteristics of milk.