链霉亲和素（Streptavidin，SA）是阿维丁链霉菌（Streptomycesavidinii）在生长过程中分泌的一种同型四聚体蛋白。同亲和素一样，一摩尔的链霉亲和素可以结合四摩尔的生物素，与生物素具有很高的亲和力。由于SA不含糖基且等电点接近于中性，因此SA在检测应用中具有比亲和素更低的非特异性结合水平。
该制品已被广泛应用于多种生物技术领域，诸如：包被免疫检测用微孔板，制备SA 偶联酶制剂，SA 偶联荧光素、SA 偶联磁珠等，进而参与酶联免疫吸附和酶催化放大实验，免疫组化化学、生物分子纯化、生物传感器、生物纳米微球、预靶向制药研究和生物芯片被料等。
增强稳定型核心链霉亲和素与天然链霉亲和素相比，去除与活性无关的序列，仅保留与活性有关的核心序列，并对序列做了修饰，热稳定性、溶解性、活性等方面相较于天然链霉亲和素，均得到大幅提升。 (该产品pI：5.68)。
阿拉丁链霉亲和素系列产品：
| 货号 | 产品名称 | 物理外观 | 储存缓冲液 | 分子量 | 来源 | 活性 (U/mg蛋白) | 关键特性 |
| R748131 | 重组单体链霉亲和素（r-mSA） | Lyophilized | Lyophilized from 10mM CBS, Trehalose, pH 9.2 | 15.1kDa | E.coli | ≥8 | N-His tag，pI=7.1，易洗脱 |
| S767455 | 重组增强稳定型核心链霉亲和素（r-se-cSA） | Lyophilized | Lyophilized from 5mM PPB, Trehalose, pH 7.4 | 53.6kDa (tetramer), 13.4kDa (monomer) | E.coli | 17-19 | 核心序列优化，序列修饰，热稳定性、溶解性、活性等提升；pI=5.68 |
| S767462 | 重组粘性链霉亲和素 (r-ScSA) | Lyophilized | Lyophilized from 5mM PBS, pH 7.4 | 54-94kDa | E.coli | ≥14 | 增强吸附性（特别适用于NC膜），保留核心活性 |
| R767460 | 重组核心链霉亲和素 (r-cSA) | Lyophilized | Lyophilized from 5mM PBS, pH 7.4 | 54kDa (tetramer), 13.5kDa (monomer) | E.coli | ≥15 | 核心序列优化；C端含半胱氨酸；pI=6.04 |
| R767461 | 重组核心链霉亲和素2 (r-cSA2) | Lyophilized | Lyophilized from 5mM PBS, pH 7.4 | 53.2kDa (tetramer), 13.3kDa (monomer) | E.coli | ≥16 | 核心序列优化；pI=6.09 |
| R767452 | 重组核心链霉亲和素4 (r-cSA4) | Lyophilized | Lyophilized from 5mM PPB, Trehalose, pH 7.4 | 55.2kDa (tetramer), 13.8kDa (monomer) | E.coli | ≥16 | 核心序列优化，序列修饰（增加了氨基的含量），稳定性、溶解性等提升；pI=8.93 |
| R767450 | 重组长臂巯基核心链霉亲和素（r-las-cSA）
| Lyophilized | Lyophilized from 20mM HEPES, Trehalose, TCEP, pH 7.0 | 54.8kDa (tetramer), 13.7kDa (monomer) | E.coli | ≥16 | 核心序列优化，C端的半胱氨酸前添加6个柔性氨基酸延长巯基臂；pI=6.09 |
| S1527913 | 重组增强稳定型核心链霉亲和素4 (r-se-cSA4) | Lyophilized | Lyophilized from 5mM PPB, Trehalose, pH 7.4 | 55.2kDa (tetramer), 13.8kDa (monomer) | E.coli | ≥17 | 去除与活性无关的序列，核心序列优化，序列修饰，热稳定性、溶解性、活性等大幅提升；pI=8.73 |
| L1527914 | 重组 低非特异性核心链霉亲和素 (r-LNS-cSA) | Lyophilized | Lyophilized from 5mM PPB, Trehalose, pH 7.4 | 56.8kDa (tetramer), 14.2kDa (monomer) | E.coli | ≥17 | 核心序列优化，序列修饰，热稳定性、溶解性、活性等大幅提升,对序列中的氨基酸进行突变，降低了偶联过程中的非特异性吸附；pI=8.93 |
使用方法：（仅供参考）
由于产品生产工艺中冻干环节会引入保护剂等，为减少您的实验误差，建议先通过内部检测方法，产品中蛋白进行准确定量后，再进行后续实验，并按实际情况进行产品用量调整。建议优先选择紫外吸收法进行定量，方法如下：
将样品从低温条件下拿出后，平衡至室温，并擦去瓶外附着的冷凝水，小心打开瓶盖，防止干粉飞溅损失。用去离子水或缓冲液进行复溶，充分溶解后，稀释至合适浓度，小心移入比色皿中，以去离子水或缓冲液为空白对照，测定样品在 280 nm 处的吸光值（建议吸光值控制在 0.1-1.5区间内），将其代入以下公式计算蛋白质浓度：
式中：C：样品原液的蛋白质质量浓度（mg/mL）
A280nm：蛋白质溶液在 280nm 处测得的吸光值
N：稀释倍数
E(0.1% at 280nm)：1 mg/mL 蛋白质的消光系数
例如将本产品冻干粉充分溶解并混匀后，取适量原液稀释 10 倍，测得其在 280 nm 处的吸光值为0.9411，则原液的蛋白浓度为10×0.9411/3.137=3 mg/mL。
注意事项：
1. 链霉亲和素冻干粉易溶于水，溶解性可达 10 mg / mL 或更高；
2. 建议使用纯水溶解；
3. 如有未溶解物质，建议延长复溶时间。也可以通过离心或其他方式除去不溶物后，再用于后续实验，不会对总蛋白产生很大的影响。
4. 考虑到蛋白质特殊性，冻干粉建议现用现配，溶解后应避免反复冻融，如需多次使用，建议按需分装后冻存（-20°C）；避免在 4°C下长期存放。
M：蛋白质分子量标准
Lane 1：S767455 单体
Lane 2：S767455 四聚体
Source
E. coli fermentation engineering strain
Product introduction
After taking the sample out of the low temperature condition, balance to room temperature, and wipe away the condensed water attached to the outside of the bottle, and carefully open the bottle cap to prevent the loss of dry powder splash. Redissolve with deionized water or buffer, after fully dissolved, dilute to a suitable concentration, and carefully move into the cuvea, using deionized water or buffer as a blank control, determine the absorbance value of the sample at 280 nm (it is recommended that the absorbance value be controlled within the range of 0.1-1.5), and substitute it into the following formula to calculate the protein concentration: Streptavidin (SA) is a homologous tetramer protein secreted by Streptomyces avidinii during its growth. As with avidin, one mole of streptavidin can bind four moles of biotin, and biotin has a high affinity. Because SA has no sugar group and its isoelectric point is close to neutral, SA has a lower non-specific binding water than avidin in detection applications. Compared with natural streptavidin, the enhanced stable core streptavidin removed the sequence unrelated to activity, only retained the core sequence related to activity, and modified the sequence, and the thermal stability, solubility, activity and other aspects were significantly improved compared with natural streptavidin. (pI: 5.68).
The product has been widely used in a variety of biotechnology fields, such as: Coated with microporous plates for immunoassay, preparation of SA coupled enzyme preparations, SA coupled fluorescein, SA coupled magnetic beads, etc., and then participate in enzyme-linked immunoadsorption and enzyme catalytic amplification experiments, immunohistochemistry, biomolecular purification, biosensors, biological nanospheres, pre-targeted pharmaceutical research and biochip materials.
Aladdin Streptavidin Product Series:
| Product No. | Product Name | Physical Appearance | Buffer | Molecular Weight | Source | Activity (U/mg protein) | Key Features |
| R748131 | Recombinant Monomeric Streptavidin (r-mSA) | Lyophilized | Lyophilized from 10mM CBS, Trehalose, pH 9.2 | 15.1kDa | E.coli | ≥8 | N-His tag, pI = 7.1, easy elution |
| S767455 | Recombinant Stability-enhanced Core Streptavidin (r-se-cSA) | Lyophilized | Lyophilized from 5mM PPB, Trehalose, pH 7.4 | 53.6kDa (tetramer), 13.4kDa (monomer) | E.coli | 17-19 | Optimized core sequence and sequence modification with improved thermal stability, solubility and activity; pI = 5.68 |
| S767462 | Recombinant Sticky Streptavidin (r-ScSA) | Lyophilized | Lyophilized from 5mM PBS, pH 7.4 | 54-94kDa | E.coli | ≥14 | Enhanced adsorption performance especially for NC membrane with retained core activity |
| R767460 | Recombinant Core Streptavidin (r-cSA) | Lyophilized | Lyophilized from 5mM PBS, pH 7.4 | 54kDa (tetramer), 13.5kDa (monomer) | E.coli | ≥15 | Optimized core sequence and C-terminal cysteine; pI = 6.04 |
| R767461 | Recombinant Core Streptavidin 2 (r-cSA2) | Lyophilized | Lyophilized from 5mM PBS, pH 7.4 | 53.2kDa (tetramer), 13.3kDa (monomer) | E.coli | ≥16 | Optimized core sequence; pI = 6.09 |
| R767452 | Recombinant Core Streptavidin 4 (r-cSA4) | Lyophilized | Lyophilized from 5mM PPB, Trehalose, pH 7.4 | 55.2kDa (tetramer), 13.8kDa (monomer) | E.coli | ≥16 | Optimized core sequence with sequence modification (increased amino-group content); improved stability and solubility; pI = 8.93 |
| R767450 | Recombinant Long-Arm Sulfhydryl Group Core Streptavidin (r-las-cSA) | Lyophilized | Lyophilized from 20mM HEPES, Trehalose, TCEP, pH 7.0 | 54.8kDa (tetramer), 13.7kDa (monomer) | E.coli | ≥16 | Optimized core sequence; six flexible amino acids added before C-terminal cysteine to extend thiol arm; pI = 6.09 |
| S1527913 | Recombinant Stability-enhanced Core Streptavidin 4 (r-se-cSA4) | Lyophilized | Lyophilized from 5mM PPB, Trehalose, pH 7.4 | 55.2kDa (tetramer), 13.8kDa (monomer) | E.coli | ≥17 | Removal of non-activity-related sequences, optimized core sequence and sequence modification; greatly improved thermal stability, solubility and activity; pI = 8.73 |
| L1527914 | Recombinant Low Non-Specific Core Streptavidin (r-LNS-cSA) | Lyophilized | Lyophilized from 5mM PPB, Trehalose, pH 7.4 | 56.8kDa (tetramer), 14.2kDa (monomer) | E.coli | ≥17 | Optimized core sequence with sequence modification; greatly improved thermal stability, solubility and activity; amino-acid mutations introduced to reduce non-specific adsorption during conjugation; pI = 8.93 |
Method of use (for reference only)
Due to the introduction of protective agents in the freeze-drying process of the product, in order to reduce your experimental error, it is recommended to first pass the internal detection method, and accurately quantify the protein in the product, and then conduct follow-up experiments, and adjust the product dosage according to the actual situation. It is recommended that UV absorption method be preferred for quantification, as follows:
After taking the sample out of the low temperature condition, balance to room temperature, and wipe away the condensed water attached to the outside of the bottle, and carefully open the bottle cap to prevent the loss of dry powder splash. Redissolve with deionized water or buffer, after fully dissolved, dilute to a suitable concentration, and carefully move into the cuvea, using deionized water or buffer as a blank control, determine the absorbance value of the sample at 280 nm (it is recommended that the absorbance value be controlled within the range of 0.1-1.5), and substitute it into the following formula to calculate the protein concentration:
C: Protein mass concentration of the sample stock solution (mg/mL)
A280nm: The absorption value of the protein solution measured at 280nm
N: dilution ratio
E(0.1% at 280nm) : extinction coefficient of 1 mg/mL protein
For example, after the freeze-dried powder of the product is fully dissolved and mixed, the appropriate amount of the stock solution is diluted 10 times, and the absorption value at 280 nm is 0.9411, then the protein concentration of the stock solution is 10×0.9411/3.137=3 mg/mL.
Note:
1. Streptavidin freeze-dried powder is easily soluble in water, with a solubility of 10 mg/mL or higher;
2. It is recommended to use pure water to dissolve;
3. If there are undissolved substances, it is recommended to extend the re-dissolution time. The insoluble matter can also be removed by centrifugation or other means, and then used in subsequent experiments, and will not have a great impact on the total protein.
4. Considering the particularity of protein, freeze-dried powder is recommended to be used on the go. Repeated freeze-thawing should be avoided after dissolution. If it is needed for multiple uses, it is recommended to be frozen after packaging as required (-20°C); Avoid long-term storage at 4°C.
M: Protein molecular weight standard
Lane 1: S767455 Monomer
Lane 2: S767455 Tetramer
ZJ26F0636288
危险品化学品经营许可证（带存储）