CHEMICAL TESTS FOR PEPTIDES AND AMINO ACIDS

Positive result for Sodium Nitroprusside Test

• Yellow to orange

• Red to purple

• Black Precipitate

Test for indole containing amino acid

Involves formation of mercuric salt

• Sakaguchi Test

• Xanthoproteic Test

• Million-Nasse Test

Positive result for Biuret Test

Test for alpha amino acids

• Basic Lead Acetate Test

• Ninhydrin/Triketohydrindene Test

• Pauly Diazo Test

Xanthoproteic Test

• Test for amino acids with benzene ring

• (+) Old rose

• Involves nitration of aromatic group

• Involves glyoxylic acid reaction

(+) Result: Old Rose

(+) Yellow to orange color

Test for peptide bonds

• Biuret Test

• Basic Lead Acetate Test

• Hopkins-Cole

• Ninhydrin Test

(+) Result for imino acid in Ninhydrin Test