牛跟腱胶原与草鱼皮胶原的结构表征及自组装行为比较

以牛跟腱和草鱼皮为原料，采用“酸-酶”结合法提取I型胶原，研究两种胶原的结构特性及其自组装行为差异。结果表明：牛跟腱胶原和草鱼皮胶原均具有I型胶原的典型结构特点，具有相似的相对分子质量和二级结构，但氨基酸含量有所差异，其中牛跟腱胶原亚氨基酸（脯氨酸+胫脯氨酸）含量要高于草鱼皮胶原。胶原的自组装结果表明，当胶原质量浓度为2 mg/m L、温度为37℃时胶原自组装速率最高。而当温度过高（>42℃）时，相比牛跟腱胶原，草鱼皮胶原的组装受到更大地抑制，这可能归因于牛跟腱胶原中更多的亚氨基酸含量赋予了其更好的热稳定性。此外，增大胶原浓度可以提升胶原凝胶的存储模量，整体而言，牛跟腱胶原凝胶的存储模量优于草鱼皮胶原凝胶。     

预处理对皮粉微观形貌和热稳定性的影响

对极性溶剂、非极性溶剂、不同质子化程度、破坏氢键度及去氨基等预处理后的白皮粉的理化性能进行了表征。结果表明：尿素浓度在1~4mol/L范围内,皮粉纤维由未经任何处理的束状到表面粘连聚集再到纤维束分散,皮胶原的热变性温度急剧下降,浓度超过4mol/L后,纤维束则开始溃散,热稳定性随尿素浓度的增加呈缓慢降低趋势;有机酸及硫酸对胶原纤维的酸解、溶胀影响比盐酸的明显,甲酸处理后皮胶原的热稳定性降低较小,而硫酸对其酸解程度明显,热稳定性下降明显;去氨基后皮粉的纤维束也有一定程度的聚集,且在纤维表面有晶体析出,热分解温度变化甚微,而热变性温度降低显著。     

草鱼皮酸溶性和酶溶性胶原蛋白的提取及性质

本文研究了从草鱼皮中提取酸溶性胶原蛋白(ASC)和酶溶性胶原蛋白(PSC)及其部分性质。草鱼皮中ASC和PSC的提取得率以干基计分别为8.0%和18.6%;对草鱼皮ASC和PSC的紫外光谱分析,最大吸收峰都接近223nm;SDS-PAGE电泳图谱显示草鱼皮胶原蛋白是由两条不同的α链组成,分子量都在100kDa以上,与猪皮I型胶原蛋白相似;草鱼皮ASC和PSC热变性温度分别为33.8、34.5℃,只比猪皮的热变性温度(37℃)低3℃左右。结果表明草鱼皮胶原蛋白在功能食品、医药、化妆品、制药等方面有潜在的应用。     

草鱼皮胶原的体外自组装动力学研究

体外自组装是天然胶原的重要分子行为特征之一,并对胶原基产品性能产生显著影响。以草鱼皮酶溶性胶原蛋白为研究对象,重点开展胶原体外自组装动力学行为、影响因素、组装纤维的微观结构及其热稳定性能研究。浊度实验和自组装程度分析的结果表明,草鱼皮胶原蛋白具备体外自组装能力,其自组装进程受胶原质量浓度、pH值、离子强度、温度等因素的影响。在pH 7～8、胶原质量浓度3～5 mg/mL、体系温度25～30 ℃以及NaCl浓度0～200 mmol/L条件下胶原自组装进程较快、自组装程度较高;组装动力学分析的结果表明,在较高的离子强度（NaCl浓度300 mmol/L）和较低的组装温度（20 ℃）时,胶原组装进程表现为：成核、组装和平衡3 个阶段,而在较高组装温度（25～30 ℃）和较低离子强度时（NaCl浓度0～200 mmol/L）,胶原组装进程表现为：快速组装段、低速组装段和平衡段;胶原纤维形态学观察结果表明,草鱼皮胶原组装纤维具有典型的D周期特征但D周期长度值（64.6 nm）小于哺乳动物胶原纤维（约67 nm）;示差扫描量热法（differential scanning calorimetry,DSC）分析结果表明,经纤维重组后,草鱼皮胶原蛋白的热稳定性得到明显提升。     

丙烯酸-丁烯醛共聚物与浸酸皮相互作用研究

研究了丙烯酸-丁烯醛共聚物与浸酸皮之间的相互作用。试验结果表明:丙烯酸-丁烯醛共聚物可明显提高浸酸皮胶原的收缩温度和热变性温度,并使皮胶原纤维软段的玻璃化转变温度升高,而丙烯酸-丁烯醛共聚物与浸酸皮胶原之间的共价键交联主要发生在皮胶原原纤维的极性区,是由丙烯酸-丁烯醛共聚物中,醛基与皮胶原纤维软段中极性氨基酸残基上的氨基反应而获得的。     

非胶原酶对热处理后胶原的水解特性分析

研究了皮胶原纤维以及胶原溶液经热处理后,再用胰酶、胰凝乳蛋白酶和木瓜蛋白酶等非胶原酶进行酶解的特性,用凝胶电泳测定水解物的分子质量及分子质量分布。结果表明:热处理温度超过胶原纤维或胶原溶液的热变性温度后,非胶原酶能够在温和的水解温度下对其进行水解。胰酶、胰凝乳蛋白酶在中性pH值下,对热变性胶原在常温下几分钟之内即可表现出良好的水解作用,而在pH值5.5以下对变性胶原的水解作用微弱;但木瓜蛋白酶在pH值5.5左右却具有良好的水解变性胶原的作用,但其水解时间需要控制在90min以上。不同的非胶原酶对胶原的酶切位置不同,会导致其水解物分子质量分布不同。研究结果表明热-酶处理有可能实现胶原纤维分子质量及分子质量分布的定向调控。     

柠檬酸钠脱铬过程中皮块及其纤维热性能的研究

利用热台偏光显微镜,通过测定皮块的湿热收缩温度、溶液胶原水解量及其纤维的干热收缩曲线,研究了蓝湿皮脱铬过程中,柠檬酸钠处理对皮块及其纤维热性能的影响.结果表明,柠檬酸钠具有脱铬和交联皮胶原的双重作用,随柠檬酸钠处理时间增加,溶液胶原水解量增加,但皮块的TS上升;柠檬酸钠脱铬过程使皮纤维热性能增强,随处理时间增加,皮纤维的热收缩率降低,DTS升高;柠檬酸钠处理可使纤维的晶区结构稳定性增加,随脱铬时间增加,皮纤维的Tcd升高.     

草鱼鱼鳔胶原性质的研究

为了有效利用鱼类废弃物,从草鱼鳔中提取酸溶性胶原(ASC)和酶溶性胶原(PSC)并对其部分性质进行研究。ASC 和PSC 的提取得率以干基计分别为4.7% 和11.1%;ASC 和PSC 的紫外光谱表明,最大吸收峰都接近于230nm;氨基酸组成分析表明,ASC 和PSC 中羟脯氨酸和羟赖氨酸的总含量分别为16.87% 和17.55%;十二烷基硫酸钠- 聚丙烯酰胺凝胶电泳(SDS-PAGE)图谱显示草鱼鳔胶原至少由两条不同的α链(α1 和α2)组成,与I 型胶原相似;ASC 和PSC 热变性温度(Td)分别为33.0、34.8℃,比猪皮胶原的热变性温度(37℃)低3～4℃。结果表明,草鱼鳔胶原有可能替代或作为补充陆生动物胶原广泛应用于工业领域。     

热处理对罗非鱼皮酸溶性胶原性质的影响

考察热处理时间对罗非鱼皮酸溶性胶原(acid-soluble collagen,ASC)理化性质和成膜能力的影响。结果发现,热处理时间对胶原的紫外吸收和分子质量分布没有明显影响;随着热处理时间的延长,ASC的比浓黏度发生下降,变性温度和热转变温度分别从32.6℃和38.15℃下降至27.0℃和29.19℃。浊度实验结果表明,当ASC在42℃条件下热处理超过10 min后,ASC不具备成纤维能力。而且,热变性的胶原还会阻碍天然胶原的纤维形成。另一方面,随着热处理时间的延长,胶原膜的抗拉伸强度从30.81 MPa增加至41.33 MPa,断裂延伸率从8.95%增加至11.59%,透明度值从2.42增加至3.33。根据扫描电子显微镜观察的结果,发现胶原膜的纤维状网络结构随着热处理逐渐转变成类似皱纹的纹理结构。以上研究结果表明,经过热变性后,罗非鱼皮ASC的成纤维能力下降,但成膜能力却出现上升。     

胭脂虫红色素对胶原膜的染色性能研究

采用胭脂虫红色素对胶原膜进行染色,通过单因素实验考察了不同染色条件对胶原膜染色效果的影响,并对染色后的胶原膜进行了相关表征。研究结果表明,最佳染色工艺为:在胭脂虫红色素浓度0.15%、温度50℃及pH值为5的染浴液中反应60 s。红外光谱分析表明,胭脂虫红分子的引入增强了胶原氢键的作用。差示扫描量热分析和热重分析表明,染色后胶原膜的热变性温度提高了10.5℃,起始分解温度升高了约90℃,耐热性得到了较大的改善。接触角和吸水率测定表明,染色后胶原膜的亲水性增加。机械性能测试结果显示,染色后胶原膜的机械强度有所提高。     

Stabilizing effect of glycerol on collagen type I isolated from different species

The stabilizing effect of glycerol on type I collagens (C) from rat tail tendon (RTC), calf skin (CSC), human placenta (HPC), and sheep skin (SSC) at elevated temperature and in urea was investigated. The protein denaturation was followed by means of differential UV-spectroscopy. The denaturation temperatures (T_d) increased proportionally to the concentration of glycerol in the reaction medium. Equations for the dependence of T_d glycerol concentration were derived. The calculated thermodynamic characteristics do not change significantly with increasing glycerol concentration. It was observed that, in the presence of glycerol, the collagen molecule was stabilized, not only by heating, but also by the action of urea.     

氨基酸组成及溶剂环境对淡水鱼胶原蛋白热稳定性能的影响

本文探讨了氨基酸组成、分布以及溶剂环境对鱼源胶原蛋白蛋白热稳定性能的影响。利用不同鱼类的胶原蛋白为实验样本,测定胶原蛋白氨基酸组成和热变性温度,通过相关性分析明确了影响胶原蛋白热变性温度的主要氨基酸种类和分布指标。结果表明,胶原蛋白中脯氨酸羟基化率、碱性氨基酸、带电荷极性氨基酸和总极性氨基酸含量与胶原蛋白热变性温度呈正相关,而亚氨基酸与非极性氨基酸含量与胶原蛋白热变性温度呈负相关(p0.01)。运用逐步多元回归分析方法,建立了脯氨酸羟基化率和带电荷极性氨基酸与胶原蛋白热变性温度之间的相关性数学模型,经验证,该模型能较好的预测鱼源胶原蛋白的热变性温度。在此基础上,进一步研究了胶原蛋白所处溶剂环境对其热稳定性能的影响。结果表明,提高水分子浸润胶原蛋白程度和体系离子强度,或降低体系pH均会显著降低胶原蛋白热稳定性能。     

Structure and characteristics of acid and pepsin-solubilized collagens from the skin of cobia (Rachycentron canadum)

Acid-solubilized collagen (ASC) and pepsin-solubilized collagen (PSC) were extracted from the skin of cobia (Rachycentron canadum). The yields of ASC and PSC were 35.5% and 12.3%, respectively. Based on the protein patterns and carboxymethyl-cellulose chromatography, ASC and PSC were composed of α1α2α3 heterotrimers and were characterised as type I collagen with no disulfide bond. Their amounts of imino acids were 203 and 191 residues per 1000 residues, respectively. LC-MS/MS analysis demonstrated the high sequences similarities of ASC and PSC. Fourier transform infrared spectroscopy spectra showed that the amide I, II and III peaks of PSC were obtained at a lower wave number compared with ASC. The thermal denaturation temperatures of ASC and PSC, as measured by viscometry, were 34.62 and 33.97°C, respectively. The transition temperatures (T(max)) were 38.17 and 36.03°C, respectively, as determined by differential scanning calorimetry (DSC). Both collagens were soluble at acidic pH and below 2% (w/v) NaCl concentration.     

尖吻鲈鱼鳞和鱼皮胶原蛋白的提取及其理化特性分析

以尖吻鲈鱼鳞和鱼皮为原料,提取并分离纯化酶溶性胶原蛋白,通过十二烷基硫酸钠-聚丙烯酰胺凝胶 电泳（sodium dodecyl sulfate-polyacrylamide gel electropheresis,SDS-PAGE）、氨基酸组成分析、差示扫描量热 （differential scanning calorimetry,DSC）、傅里叶变换红外光谱、X射线衍射和Zeta电位以及溶解度研究,分析 和比较了其主要理化性质。冷冻干燥后鱼鳞和鱼皮胶原蛋白得率（干质量）分别为2.3 g/100 g和47.3 g/100 g; SDS-PAGE结果显示两种胶原蛋白构型均为[α1(Ⅰ)]2α2(Ⅰ),初步判断属于Ⅰ型胶原蛋白;DSC结果显示鱼鳞和鱼 皮胶原蛋白热变性温度（Td）分别为37.54 ℃和36.74 ℃;傅里叶变换红外光谱和X射线衍射结果显示胶原蛋白经 胃蛋白酶处理后仍能保持其完整的三股螺旋结构;Zeta电位结果显示鱼鳞和鱼皮胶原蛋白等电点分别为pH 6.40和 pH 6.64;溶解度研究结果显示两种胶原蛋白在酸性条件和低NaCl质量浓度下均表现出良好的溶解性。     

Preparation and thermal stability of collagen from scales of grass carp (<Emphasis Type="Italic">Ctenopharyngodon idellus</Emphasis>)

Grass carp (Ctenopharyngodon idellus) scales (GCS) was swollen in water and treated with microwave for 2 min, followed by decalcifying with 8% aqueous citric acid solution. The collagen of GCS was then prepared by limited pepsin digestion with a yield of 25.64% on dry weight basis. SDS-PAGE, FT-IR and amino acid composition analysis indicated that the pepsin-solubilized collagen from GCS was typical type I collagen, consisting of three different α chains, α₁, α₂ and α₃. The thermal stability of pepsin-solubilized collagen from GCS was studied using viscometry, circular dichroism (CD) and Raman spectroscopies. The denaturation temperature (T _d) of collagen solution was 32 °C determined by viscometry. CD spectra analysis showed that the Td of GCS solution was between 35 °C and 40 °C, and further confirmed by Raman spectra. Thus, a large amount of collagen could be obtained from GCS and the preparation method is safe and time-economizing, and GCS will have potential as an important collagen source for use in various industries.     

云南鲷鱼骨胶原蛋白的制备及其理化性质

以云南鲷鱼骨为原料,采用低温酸法提取制备鱼骨中的酸溶性胶原蛋白（acid-soluble collagen,ASC）, 并对ASC的氨基酸组成、亚基组成、红外吸收、紫外吸收、热稳定性、X射线衍射、微观结构、多肽片段以及溶解 性进行了全面的分析。氨基酸组成表明ASC主要含甘氨酸、脯氨酸和丙氨酸,而酪氨酸、蛋氨酸和半胱氨酸含量 较低;十二烷基硫酸钠-聚丙烯酰胺凝胶电泳结果显示ASC为Ⅰ型胶原蛋白;ASC在230 nm波长处有最大紫外吸收 峰;傅里叶变换红外光谱和X射线衍射图谱表明ASC分子排列紧凑,保持了其原有的三螺旋结构;差示扫描量热分 析结果显示ASC的变性温度分别为86.5 ℃和226.2 ℃,有较好的热稳定性;扫描电子显微镜显示ASC分子分布均匀、 表面光滑呈三维立体结构;多肽片段分析结果显示鱼骨胶原的氨基酸构成主要为Gly-X-Y,符合胶原蛋白的一级结构 的特点;在pH值小于4的条件下,ASC溶解度较高,当NaCl质量分数大于4%时,ASC溶解度剧烈下降。     

TEXTURE AND COLOUR CHANGES IN MEAT DURING COOKING RELATED TO THERMAL DENATURATION OF MUSCLE PROTEINS1

Differential scanning calorimetry was used to select temperatures that diferentiated between thermal denaturation of the three major structural protein species in bovine muscle: myosin, collagen and actin. Samples of m. semimembranosus, m. semitendinosus and m. psoas major were heated to those different temperatures and evaluated sensorially. Three groups of sensory properties were needed to describe the main texture changes observed in the meat: 1. Firmness 2. Fiber cohesivity, bite-off force, residual bolus 3. Juiciness Firmness increased with thermal denaturation of the myofibrillar proteins (myosin; 40-60d?C and actin; 66-73d?C). Fiber cohesivity etc. decreased with collagen denaturation (56-62d?C). Reduction in juiciness was primarily associated with actin denaturation, while cooking loss increased over the whole temperature range. The property “total chewing work”, a composite of the first two texture groups mentioned, yielded like the judges' “total texture preference”, optimal texture in the 60-67d?C temperature region, implying denatured myosin and collagen but native actin. This meat was light pink-gray in colour, while the cooking juice released was dark red.     

海蜇伞部酶促溶性胶原蛋白的热变性动力学

为阐明海蜇伞部酶促溶性胶原蛋白(pepsin-solubilized collagen,PSC)的热变性反应机理,以保持完整三螺旋结构的PSC为研究对象,通过微量热仪测定不同升温速率条件下PSC的变性温度,以及采用34、35、36、37、38、39℃加热不同时间后的PSC残存率,并进行热变性动力学分析。结果表明,海蜇伞部PSC对热变化敏感,随着加热温度升高,单位时间内提高的热量增加,使海蜇伞部PSC变性速率加快,完成变性时间缩短;随着升温速率的减慢,吸热峰逐渐向低温区移动,即变性温度随升温速率的减慢而降低,但升温速率的变化对反应热并无显著影响。反应级数为0.9的回归方程能够较好地描述PSC热变性过程,在恒温34、35、36、37、38℃及39℃的条件下,PSC变性的D90值(90%蛋白变性所需时间)分别为53.76、26.11、15.75、4.89、4.26、2.55 min,Z90值(D值降低90%的温度变化)为3.69℃,表观活化能为481.90 k J/mol。研究结果可为海蜇胶原蛋白的进一步开发利用提供理论参考。     

温度对乌鳢鱼皮胶原蛋白肽聚集体结构及理化特性的影响

研究乌鳢鱼皮胶原蛋白肽在20～52℃低温诱导下自组装体的结构稳定性与理化性质,比较分析聚集体变化过程中圆二色谱、自组装动力学、微观结构、凝胶强度、粒径、黏度、变性温度和红外光谱的变化.结果表明:在20～30℃温度范围内,升温对乌鳢鱼皮胶原蛋白肽自组装速率及聚集体稳定性具有促进作用,组装成核时间缩短13.5 min,形成...     

Isolation and characterization of collagen from the skin of deep-sea redfish (Sebastes mentella)

ABSTRACT:  To make more effective use of underutilized resources, acid-solubilized collagen (ASC) and pepsin-solubilized collagen (PSC) were isolated from the skin of deep-sea redfish ( Sebastes mentella ) and characterized for their potential in commercial applications. The yield of ASC (47.5%) was lower compared to PSC (92.2%), but the purity of ASC was significantly higher. The intrinsic viscosity of ASC (15.9 dL/g) was greater than PSC (14.6 dL/g), indicating a higher average molecular weight of ASC on account of the high proportion of polymers of collagen. The denaturation temperatures of ASC and PSC were 16.1 and 15.7 °C, respectively, suggesting the triple helical structure of PSC was still predominant. The amino acid profiles of ASC and PSC were similar with lower imino acid content than most other species, which might be the reason for the lower denaturation temperature. SDS-PAGE and FTIR showed that both ASC and PSC were type I mainly with slight structure differences. ASC held its triple helical structure well, and possessed a higher extent of intermolecular cross-link. While the structure of PSC was changed slightly due to the loss of N- and C-terminus domains, the triple helical structure was still predominant as a result of the formation of more and/or stronger hydrogen bond.