The Warburg–Christian method is an ultraviolet spectroscopic protein and nucleic acid assay method based on the

absorbance Absorbance is defined as "the logarithm of the ratio of incident to transmitted radiant power through a sample (excluding the effects on cell walls)". Alternatively, for samples which scatter light, absorbance may be defined as "the negative log ...

UV light Ultraviolet radiation, also known as simply UV, is electromagnetic radiation of wavelengths of 10–400 nanometers, shorter than that of visible light, but longer than X-rays. UV radiation is present in sunlight and constitutes about 10% of t ...

at 260 nm and 280 nm wavelengths. Proteins generally absorb light at 280 nanometers due to the presence of

tryptophan Tryptophan (symbol Trp or W) 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 aromat ...

and

tyrosine -Tyrosine or tyrosine (symbol Tyr or Y) or 4-hydroxyphenylalanine is one of the 20 standard amino acids that are used by cells to synthesize proteins. It is a conditionally essential amino acid with a polar side group. The word "tyrosine" is ...

. Nucleic acids absorb more at 260 nm, primarily due to

purine Purine is a heterocyclic aromatic organic compound that consists of two rings (pyrimidine and imidazole) fused together. It is water-soluble. Purine also gives its name to the wider class of molecules, purines, which include substituted puri ...

and

pyrimidine Pyrimidine (; ) is an aromatic, heterocyclic, organic compound similar to pyridine (). One of the three diazines (six-membered heterocyclics with two nitrogen atoms in the ring), it has nitrogen atoms at positions 1 and 3 in the ring. The oth ...

bases. The Warburg–Christian method combines measurements at these wavelengths to estimate the amounts of protein and nucleic acid present. Original description of the method appeared in 1941.Isolierung und Kristallisation des Gärungsferments Enolase, 1941, Biochemische Zeitschrift The method is named for its creators, the German cancer researcher

Otto Heinrich Warburg Otto Heinrich Warburg (, ; 8 October 1883 – 1 August 1970) was a German physiologist, medical doctor, and Nobel laureate. He served as an officer in the elite Uhlan (cavalry regiment) during the First World War, and was awarded the Iron Cross ...

, Nobel Prize winner, and his employee Walter Christian of the

Kaiser Wilhelm Institute for Biology The Kaiser Wilhelm Society for the Advancement of Science () was a German scientific institution established in the German Empire in 1911. Its functions were taken over by the Max Planck Society. The Kaiser Wilhelm Society was an umbrella organi ...

in Berlin.

References

Protein methods Analytical chemistry Chemical tests {{analytical-chem-stub