Why is biuret reagent purple?

Why is biuret reagent purple?

Biuret Reagent The biuret test uses an alkaline mixture, or reagent, composed of potassium hydroxide and copper sulfate. The normal color of biuret reagent is blue. The reagent turns violet in the presence of peptide bonds — the chemical bonds that hold amino acids together.

Is BSA a hazardous?

The product contains no substances which at their given concentration, are considered to be hazardous to health.

Is FBS and FCS the same?

There is no difference between FBS and FCS, it is just a naming preference. So FBS and FCS are the same and both fetal, but different to BS or CS which would come from a calf already born.

Does BSA have biotin?

It is said that some preparations of BSA may contain biotin from serum. Thus, the presence of biotin in BSA is not usually a concern. However, if loss of signals happens, another BSA product or biotin-free blocking agent should be used for the SA-HRP incubation step.

Is bovine serum albumin similar to human albumin?

Human serum albumin is encoded by the ALB gene. Other mammalian forms, such as bovine serum albumin, are chemically similar. Serum albumin is produced by the liver, occurs dissolved in blood plasma and is the most abundant blood protein in mammals. Albumin in the urine usually denotes the presence of kidney disease.

Does BSA expire?

To effectively preserve the integrity of BSA, it should be stored at the recommended temperature and protected from light. For stability and optimal performance, this product should be stored at 2 to 8 C. Do not use after the expiration date.

What does BCA measure?

The BCA protein assay is used for quantitation of total protein in a sample. The principle of this method is that proteins can reduce Cu+2 to Cu+1 in an alkaline solution (the biuret reaction) and result in a purple color formation by bicinchoninic acid.

What is the function of BSA?

Bovine Serum Albumin (BSA) is used in a variety of laboratory applications including its function as a protein concentration standard, its function as a cell nutrient and its ability to stabilize enzymes during restriction digest.

Is Bovine Serum Albumin safe?

The product contains no substances which at their given concentration, are considered to be hazardous to health. Although the serum used to manufacture this product has been tested and shown to be negative for certain infectious agents, no test is 100% accurate.

Why is FBS so expensive?

FBS is also the most expensive and difficult to source serum, with prices ranging from 3x – 10x more than other bovine serum products. Growing demand, coupled with a lower supply of FBS has resulted in a volatile market for US FBS and consequently prices have increased significantly in the past few years.

How is BSA made?

Manufacturing Methods. Bovine serum albumin (BSA) is purified from serum using one of three different purification methods: cold-organic solvent fractionation, heat shock and ion exchange chromatography. Mannuzza and Montalto suggest that the best way to address this issue is to match the BSA to its intended use.

What is BCA reagent?

BCA is a weak acid composed of two carboxylated quinoline rings and serves the purpose of the Folin reagent in the Lowry assay, namely, to react with the product (Cu1 + ions) of complexes between copper ions and peptide bonds to produce a purple end product that strongly absorbs at 562 nm (Smith et al., 1985).

Why is BSA used as a protein standard?

BSA is used because of its stability to increase signal in assays, its lack of effect in many biochemical reactions, and its low cost, since large quantities of it can be readily purified from bovine blood, a byproduct of the cattle industry. …

What is a working reagent?

The working reagent, based on bicinchoninic acid (BCA), is used for the colorimetric detection of protein and is diluted to a working range. 200uL of the working reagent is added to the microplate. The plate has to shake briefly and be incubated for 30 minutes at 37 degrees C.

How does BSA blocking work?

Blocking of non-specific binding is achieved by placing the membrane in a dilute solution of protein – typically 3-5% Bovine serum albumin (BSA) or non-fat dry milk (both are inexpensive) in Tris-Buffered Saline (TBS) or I-Block, with a minute percentage (0.1%) of detergent such as Tween 20 or Triton X-100.

What is the best test reagent for protein quantitation?

Biuret reagent This is found with dipeptides. The reagent is commonly used in the biuret protein assay, a colorimetric test used to determine protein concentration by UV/VIS spectroscopy at wavelength 540 nm.

What color does biuret turn in the presence of protein?


How do you make bovine serum albumin?

For a 10% (100 mg/mL) stock solution of BSA, dissolve 1 g powdered Fraction V or molecular biology grade BSA in 10 mL of distilled H2O; to avoid clumping, dissolve by layering the powder on the surface of the liquid. Gently rock the capped tube until the BSA has dissolved completely.

Does FBS contain BSA?

The globular protein, bovine serum albumin (BSA), is a major component of fetal bovine serum. FBS is not a fully defined media component, and as such may vary in composition between batches. As a result, serum free and chemically defined media (CDM) have been developed as a matter of good laboratory practice.

How long can you keep BSA solution?

Lyophilized BSA although stable at room temperature for 3 weeks, should be stored 2-8°C. Upon reconstitution BSA should be stored at 4°C between 2-7 days and for future use below -18°C.

Is BSA stable in water?

SOLUBILITY / SOLUTION STABILITY: Albumins are readily soluble in water and can only be precipitated by high concentrations of neutral salts such as ammonium sulfate. The solution stability of BSA is very good (especially if the solutions are stored as frozen aliquots).