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Background
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Protein is an extremely complex polymer compound formed by the combination of alpha-amino acids with amide bonds (peptide bonds). It is the main nitrogen-containing substance in organisms; it is related to cell structure, enzymes, hormones, viruses, immunity, material transport and genetics. The common areas of content determination are shown in Figure 1.
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Protein detection methods
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The methods of detecting protein content can be roughly summarized into two: a general nitrogen determination method, which calculates the protein content based on the nitrogen content; the other is based on the physical and chemical properties of the protein, using corresponding equipment for testing, and establishing a standard curve, and then calculate the protein content. Common protein detection methods are shown in Figure 2.
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Common methods of protein quantification
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Protein quantification exists in many fields, and its common methods are shown in the table below
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Uses
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Common protein detection methods
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Note
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Measure total protein to calculate target substance concentration in biological sample
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BCA method
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Used in conjunction with other substance detection kits, such as detecting the content of enzymes, ions and cytokines in tissue and cell samples
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In Western Blot detection, the total protein of the sample is determined to determine the sample amount
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BCA method
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Use with Western Blot reagent
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Determination of serum (plasma) total protein content
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Biuret Method
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As the evaluation basis for disease diagnosis
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Determine the content of target protein in protein purification
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Coomassie brilliant blue method, BCA method
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Such as enzyme extraction
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Advantages and disadvantages of different methods
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Methods
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Advantages
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Disadvantages
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BCA method
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1.Simple operation and high sensitivity
2.There are many types of samples that can be tested
3.Not affected by chemical substances such as detergents
4.High accuracy and good linearity
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Affected by chelating agent and slightly higher concentration of reducing agent
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Coomassie brilliant blue method
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1.High sensitivity
2.The measurement is fast and simple, with good color stability
3.Relatively few interfering substances, not affected by reducing agents such as mercaptoethanol, complexing agents such as EDTA, sugars, etc.
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1.Due to the different contents of arginine and aromatic amino acids in various proteins, the Coomassie Brilliant Blue method has large deviations when used in the determination of different proteins
2.There are still some interferences, such as glycerol, acetic acid, detergents, and 0.1M NaOH alkaline buffer solvents
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Biuret Method
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1.It is not affected by temperature and produces similar colors to different proteins
2.Good repeatability
3.High accuracy, not affected by the type of protein
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1.Poor sensitivity
2.There are many interfering substances, and both chelating agents and reducing agents will interfere with the reaction
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UV absorption method
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1.Simple, sensitive and fast
2.Do not consume samples
3.Low-concentration salts do not interfere with the determination
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1.Low sensitivity
2.Strong nucleic acid interference
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Kjeldahl Method
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The results are accurate and reproducible
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1.Complex operation
2.Time-consuming and large reagent consumption
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Folin Phenol Method
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High Sensitivity
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1.Poor anti-interference ability
2.Low reaction rate and long time-consuming
3.Poor stability
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Elabscience company protein test kit
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Quantitative protein detection has a great effect on the detection of various substances and the diagnosis of diseases. In order to meet the needs of customers scientific research, based on the advantages and disadvantages of each detection method, Elabscience has developed three protein content test kits with different principles. It contains a complete set of reagents and standards required for protein detection, and is accompanied by detailed operating instructions, which can help you quickly obtain accurate and reproducible results, save time and efficiency, have good performance, and comprehensive coverage, which can meet the protein content of customers in various samples. The measured requirements are as follows:
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Cat Number
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Product name
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Detection range
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Sample type
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E-BC-K318-M
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BCA Protein Colorimetric Assay Kit
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0.0165-1 mg/mL
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Application are wide, suitable for a variety of samples
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E-BC-K165-M
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Biuret Protein Colorimetric Assay Kit
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0.58-100 g/L
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Suitable for high concentration samples such as serum (plasma)
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E-BC-K165-S
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Bradford Protein Colorimetric Assay Kit
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0.373-80 g/L
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E-BC-K168-M
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Bradford Protein Colorimetric Assay Kit
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0.046-0.6 mg/mL
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Suitable for serum, plasma, animal tissue
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E-BC-K168-S
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BCA Protein Colorimetric Assay Kit
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0.026-1.2 mg/mL
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