Post Lab Exp 3: Proteins Flashcards
is the most abundant substance in the cell next to water
Protein
Protein comprises ___% of its over-all mass
15%
Protein is composed of ______ as its building block.
amino acids
Protein is linked together with peptide bonds with a positive charged ______ containing group at one end and a negatively charged ____ group
positive charge nitrogen group
negative charge carboxyl-group
– a dipeptide, a sweetener that has no sugar
component
Aspartame
– a tripeptide
– an antioxidant that prevents
damage to cellular
components caused by free
radicals.
Glutathione
General test for proteins,
detecting peptide bonds
Biuret Test
Reagents of Biuret Test
KOH, hydrated
CuSO4
, Potassium sodium
tartarate
Positive result of Biuret Test
– Violet solution
General test for proteins
except proline (yellow)
Ninhydrin
Test for the –NH2 group in
free amino acid
Ninhydrin Test
What is the Reagent of Ninhydrin
Ninhydrin
Positive result of Ninhydrin Test
Positive Result - a deep blue
or purple color solution
Test for indole group,
tryptophan
Hopkins-Cole Test
Reagent of Hopkins-Cole Test
Hopkin’s Cole
reagent and conc. H2SO4
Hopkins Cole Test Positive Result
Positive Result: purple ring at
the interface of two liquids
The indole group of tryptophan reacts with _____ in the presence
of concentrated H2S04
to give a purple color
glyoxylic acid
Test for activated aromatic rings,
Tyrosine and tryptophan
Xanthoproteic Test
What are the reagents of Xanthoproteic Test
Reagents: Conc. Nitric Acid,
ammonium hydroxide
What is the Positive Result if Xanthoprotei Test
Positive result: Yellow or dark orange
solution or precipitate
When the sample is treated with a concentrated nitric acid it undergoes
______ with the aromatic amino acids such as tyrosine and tryptophan
and forms a yellow colored
nitration
In Xanthoproteic test, ________ is not an activated benzene ring so it will not react
Phenylalanine
Test for guanidine group,
arginine
Sakaguchi Test
What are the reagents of Sakaguchi Test
Reagent: α-Naphthol and a drop
of sodium hypobromite
What is teh positive result for sakaguchi test?
red-colored
complex solution
