Activity 8 Flashcards
(21 cards)
- are polymers of amino acids just as polysaccharides are polyumers of monosaccharides
- are very complex substances of high molecular weight which on HYDROLYSIS yield many knids of amino acids in addition to other products of decomposition.
- the hydrolytic changes are produced by _________ (3)
proteins
acids, bases, and specific enzymes
Ninhydrin (____) is a powerful oxidizing agents
triketohydrindenehydrate
a reaction with alpha - amino acids and proteins to give intense blue or purple compound.
Ninhydrin reaction
The amino acids Proline and Hydroxyproline react with _____ to give the YELLOW color.
Ninhydrin
(WHAT REACTION) In the presence of a free carboxyl group adjacent to the amino group such as is present in alpha-amino acids quantitative amounts of CO2 are released and this reaction has been used by _________ as a basis for a quantitative determination of alpha-amino acids. This reaction is also iven by ammonia, ammonium salts, primary amines, and amides but without the liberation of CO2
NINHYDRIN REACTION
Van Slyke
is called the “Biuret test” because it is given by the substance Biuret obtained upon heating urea to 180 degrees celcius
Piotrowski’s reaction
- another illustration of ammonia chemistry
- reaction where NH4OH dissolves Cu(OH2 to form dark blue CU(NH3)4++ ion
- generally thought that it is the acid amide group (-CONH2)or some other groups na same vibes
Biuret (Piotrowski’s) Reaction
This reaction involves nitration of the benzene nucles and the formation of a YELLOW to an ORANGE color on rendering the resulting compounds alkaline.
Xanthoproteic reaction
presence of tryptophan and tyrosine = yellow to orange, tryptophan more of a red
phenylalanine = colorless
xanthoproteic reaction
This reaction is given by most of the monohydroxylbenzene derivatives and to some extent some dihydroxybenzenederivatives.
Phenol & Tyrosine - faint pink to pure dark red
Resorcin (dihydroxybenzene) - yellowish to brownish red
Millon’s Reaction
test that is a vary good indication of presence of Tyrosine
Millon’s
The indole group such as is present in tryptophan condenses witha number of aldehydes like Glyoxylic acid in the presence of H2SO4 forming a VIOLETcomplex.
pure H2SO4 must be used since excessive amounts of oxidizing substances such as nitrites, nitrates, chlorides, and chlorates in impure acid interferes with the test
HOPKINS-COLE Reaction
The addition of bromine water and n-amyl alcohol to a asolution containing free Tryptophan results in the formation of a PINKISH LAVENEDER or violet color.
Bromine Water test
In bromine water test, presence of excess bromine water results to ______ and may be masked by the color of the reagent.
disappearance of the pink color
Tyrosine and Histidine react forming red or purple condensation products
Pauly reaction
In Pauly reaction, sulfanilic acid reacts with HONO (formed from NaNO2 and Hcl) in the cold forming diazobenzene sulfonic acid bya process called
this couples with amines, phenols, imidazoles to form highly colored azo dyes, the monoazo and the bis-azo products.
diazotization
Substances which contain the guanidine group react with alpha-naphthol and an oxidizingagent such as sodium hypobromite to give a RED or ORANGE color.
Presence of ARGININE
SAKAGUCHI reaction
What gas is liberated in the Ninhydrin reaction
CO2
A very dilute CuSO4 is used in the biuret test. Why?
in order to have the blue color, a very dilute solution is needed because excess in Cu2+ obscures the true color which is supposed to be intense blue or purple.
Why should excess bromine water be avoided in the test for free typtophan?
The orange or yellow color of the reagent masks the pink color of the tryptophan
Which test can show the hydrolytic reaction of protein by Trypsin?
SAKAGUCHI reaction - shows how trypsin split the peptide bonds on the carboxylic side of arginine and lysine
