The Pauly reaction is a

chemical test In chemistry, a chemical test is a qualitative or quantitative procedure designed to identify, quantify, or characterise a chemical compound or chemical group. Purposes Chemical testing might have a variety of purposes, such as to: * Determine ...

used for detecting the presence of

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 non-essential amino acid with a polar side group. The word "tyrosine" is from the G ...

histidine Histidine (symbol His or H) is an essential amino acid that is used in the biosynthesis of proteins. It contains an α-amino group (which is in the protonated –NH3+ form under biological conditions), a carboxylic acid group (which is in the ...

in proteins. It is named after German chemist

Hermann Pauly Hermann Pauly (18 July 1870 – 31 October 1950) was a German chemist and inventor. He is known for the Pauly reaction, a chemical test used for detecting the presence of tyrosine or histidine in proteins. Early years Hermann Pauly was born i ...

, who first described the reaction. When proteins containing either tyrosine or histidine are reacted with diazotized

sulfanilic acid Sulfanilic acid (4-aminobenzenesulfonic acid) is an organic compound with the formula H3NC6H4SO3. It is an off-white solid. It is a zwitterion, which explains its high melting point. It is a common building block in organic chemistry."Sulphan ...

under alkaline conditions, a red color is formed by a

coupling reaction A coupling reaction in organic chemistry is a general term for a variety of reactions where two fragments are joined together with the aid of a metal catalyst. In one important reaction type, a main group organometallic compound of the type R-M (R = ...

References

Protein methods Biochemistry detection reactions {{analytical-chemistry-stub