chemical tests for proteins Flashcards
(38 cards)
(+) for peptide bonds
biuret test
red coloration
nitroprusside test
reagents of conc. HNO3 and conc. NaOH
xanthoproteic test
(+) for phenolic group of tyrosine
millon’s test
red to red-orange color
sakaguchi test
reagents of NaOH and CuSO4
biuret test
(+) for the indole group of tryptophan
hopkins cole test
(+) for methionine and cysteine
fohl’s test
(+) for guanidino group of arginine
sakaguchi test
reagent is 1,2,3-indanetrione monohydrate / triketohydrindene with EtOH
ninhydrin test
(+) for cysteine
nitroprusside test
(+) for histidine and tyrosine
pauly’s test
reagent is lead acetate
fohl’s test
blue to blue-purple or yellow-orange product
ninhydrin test
(+) for proline in orsnge residue
ninhydrin test
pink to violet to blue coloration
biuret test
principle is complexation thru mercuration & nitration or nitrosation/ complexation of nitrohydroxyphenyl derivatives with Hg2+
millons test
(+) for F, Y, W aromatic AAs
xanthoproteic test
(+) for free alpha amino acids and amines
ninhydrin test
principle is complexation of copper with a peptide bond
biuret test
reagents are alpha naphthol, NaOH, NaOBr, urea
sakaguchi test
principle is diazotized sulfanilic acid with amino phenol to form a red azor in cold conditions
pauly’s test
reagent is Na2Fe(CN)5NO in dilute NH3
nitroprusside test
old rose/ flesh/ purple-red ppt.
millons test
