100/100 MLS 2101 LAB FINALS
nitration of amino acids that contain benzene ring will yield nitrobenzene
give a yellow to orange coloration upon when treated with concentrated nitric acid and addition of alkali in xanthoproteic test
phenylalanine
gives negative or weakly positive reaction in xanthoproteic test though this amino acid contains aromatic nucleus because it is difficult to nitrate under normal condition
purple color at the interface
positive result for Hopkin's Cole test
yellow to orange coloration
positive result for xanthoproteic test
glyoxylic acid
prepared by reducing oxalic acid with magnesium powder or sodium amalgam
proteios
proteins are derived from the Greek __ meaning of primary importance
10% sodium hydroxide, 0.5% copper sulfate
reagents in biuret test
Hopkin's Cole reagent with glyoxylic acid and conc. sulfuric acid
reagents used in Hopkin's Cole test
nitric acid, 40% NaOH
reagents used in xanthoproteic test
glacial acetic acid
which has been exposed to the sunlight also contains glyoxylic acid
1 ml
__ of Hopkins-Cole reagent added
1ml
__ of conc. HNO3 in all test tubes added in xanthoproteic test
2ml
__ of test solutions and distilled water used in Hopkin's Cole test
2ml
__ of test solutions and distilled water used in biuret test
2ml
__ of test solutions and distilled water used in xanthoproteic test
2ml
___ of 10% sodium hydroxide added in biuret test
2ml
___ of 40 % NaOH to all test tubes added in xanthoproteic test
1 ml
___ of conc. sulfuric acid gently added along the wall of the test tube in Hopkin's Cole test
Hopkin's Cole test
aka glyoxylic acid reaction
Hopkin's Cole test
aldehyde present in the reagent will cause the formation of a blue or a violet color ring due to the formation of a complex between the reagent and the indole of tryptophan in these proteins
collagen and gelatin
do not give a positive reaction in xanthoproteic test
drop by drop
how is 0.5% copper sulfate solution added in biuret test
Hopkin's Cole test
indole group of tryptophan reacts with glyoxylic acid in the presence of conc. sulfuric acid to give a purple colored complex
biuret test
is a chemical test that can be used to check for the presence of at least 2 peptide bonds in a given analyte
biuret
is a compound formed by heating urea to 180 °C and when treated with dilute copper sulfate in alkaline condition, a purple colored compound is formed
xanthoproteic test
is used to detect amino acids containing an aromatic nucleus (tyrosine, tryptophan, and phenylalanine) in a protein solution which gives yellow color nitro derivatives on heating with conc. nitric acid and addition of alkali
no purple color
negative result for Hopkin's Cole test
no yellow to orange coloration
negative result for xanthoproteic test
no change in color, solution remains blue
negative result of biuret test
5% egg albumin solution
test solution in biuret test
1% tryptophan, 1 % glycine, 5% egg albumin solution
test solutions in Hopkin's Cole test
1% tyrosine, 1% tryptophan, 1% phenylalanine, 5% egg albumin solution
test solutions used in xanthoproteic test
Hopkin's Cole test
test used for detecting presence of tryptophan in proteins
biuret test
test used to gauge the amount of protein present in the analyte
xanthoproteic test
test where solution is cooled under tap water
biuret test
the positive result is the formation of pale purple colored (or mauve colored) coordination compounds of the copper (II) ion (when the solution is sufficiently alkaline)