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The complete data for Tryptophan ... Molar mass: 204.23 g·mol −1 Systematic name: (S)-2-Amino-3-(1H-indol-3-yl)-propanoic acid Abbreviations: W, Trp Synonyms:
In biochemistry, the molar absorption coefficient of a protein at 280 nm depends almost exclusively on the number of aromatic residues, particularly tryptophan, and can be predicted from the sequence of amino acids. [6] Similarly, the molar absorption coefficient of nucleic acids at 260 nm can be predicted given the nucleotide sequence.
Tryptophan (symbol Trp or W) [3] is an α-amino acid that is used in the biosynthesis of proteins.Tryptophan contains an α-amino group, an α-carboxylic acid group, and a side chain indole, making it a polar molecule with a non-polar aromatic beta carbon substituent.
This characteristic is used in quantitative analysis, notably in determining the concentrations of these amino acids in solution. [1] [2] Most proteins absorb at 280 nm due to the presence of tyrosine and tryptophan. Of the aromatic amino acids, tryptophan has the highest
Extinction coefficient refers to several different measures of the absorption of light in a medium: Attenuation coefficient , sometimes called "extinction coefficient" in meteorology or climatology Mass extinction coefficient , how strongly a substance absorbs light at a given wavelength, per mass density
The Bradford protein assay (also known as the Coomassie protein assay) was developed by Marion M. Bradford in 1976. [1] It is a quick and accurate [2] spectroscopic analytical procedure used to measure the concentration of protein in a solution.
At a wavelength of 260 nm, the average extinction coefficient for double-stranded DNA is 0.020 (μg/mL) −1 cm −1, for single-stranded DNA it is 0.027 (μg/mL) −1 cm −1, for single-stranded RNA it is 0.025 (μg/mL) −1 cm −1 and for short single-stranded oligonucleotides it is dependent on the length and base composition.
The Beer–Lambert law can be applied to the analysis of a mixture by spectrophotometry, without the need for extensive pre-processing of the sample. An example is the determination of bilirubin in blood plasma samples. The spectrum of pure bilirubin is known, so the molar attenuation coefficient ε is known.