18 Questions
The xanthoproteic test is used to detect the presence of ______ amino acids.
aromatic
Ninhydrin test is used to detect the presence of ______ in a compound.
amino acids
The Ninhydrin test results in a deep purple color indicating the presence of ______, primary/secondary amines, and amino acids.
ammonia
The Ninhydrin solution acts as an ______ agent in the Ninhydrin test.
oxidizing
Decarboxylation and deamination are processes that can occur during the Ninhydrin test to detect the presence of ______.
aldehydes
A negative result in the Ninhydrin test indicates the absence of ______, primary/secondary amine, or amino acid.
ammonia
The Xanthoproteic test detects amino acids containing an __________ nucleus.
aromatic
The Xanthoproteic test is used to detect amino acids containing ________ groups.
phenolic
The Ninhydrin test can yield a yellow to yellow-orange color result for amino acids like ________ and hydroxyproline.
proline
In the Xanthoproteic test, the appearance of a dark yellow or orange-colored solution indicates the presence of ________ groups.
aromatic
The addition of the Ninhydrin reagent produces an iminium salt, resulting in a distinct yellow-orange color for amino acids like ________.
proline
Ninhydrin solution is used for protein suspension in intact protein to detect ammonia, primary or secondary amine, or free alpha-amino group present in a compound. The product produced is called Ruhemann’s complex. What is the principle of Ninhydrin test? - Decarboxylation and ______
deamination
The Xanthoproteic test facilitates the nitration of amino acids with the help of ________.
HNO3
Which amino acid gives a positive result in Xanthoproteic test? - Only the ______ and tryptophan
tyrosine
What is the principle of Xanthoproteic test? - ______ - In nitration, the nitro group should substitute to the carbon and aromatic ring
Nitration
Which gives the positive result in the Xanthoproteic test? - It is the intact protein and the ______ hydrolyzate
base
What is the visible result for Xanthoproteic test? - Yellow ______
precipitate
What are the reagents of Hopkins Cole Test? - Conc. ______
aldehydes
Study Notes
Sakaguchi Test
- Purpose: Detect and quantify the presence of guanidinium groups, specifically arginine
- Function of reagents:
- NaOH: Allows the reaction to occur by making the solution alkaline
- NaOCl: Oxidizing agent that reacts with napthol to produce a red complex product
- Napthol Solution: Condensation agent that forms a strong base with the hydroxide ion (OH-)
- Principle: Guanidin group (side chain of arginine) reacts with napthol to produce a red-colored complex product
- Result:
- Positive: Red-colored result indicates the presence of arginine or guanidine group
- Negative: Absence of red color indicates no arginine or guanidine group present
Ninhydrin Test
- Purpose: Detects ammonia, primary or secondary amines, or free-alpha amino group present in a compound
- Function of reagents:
- Water: Facilitates the connection of the amine group of the amino acid with Ninhydrin
- Ninhydrin solution: Acts as an oxidizing agent
- Principle: Decarboxylation and deamination lead to the liberation of aldehyde, CO2, NH3, and hydrindination (reduced form of ninhydrin)
- Result:
- Positive: Deep purple color indicates the presence of ammonia, primary/secondary amines, or amino acids
- Negative: No color change indicates the absence of ammonia, primary/secondary amines, or amino acids
Xanthoproteic Test
- Purpose: Detects amino acids containing phenolic or indolic groups (phenylalanine, tyrosine, and tryptophan)
- Function of reagents:
- Conc. HNO: Denatures protein, breaks peptide bonds, and initiates nitration reaction with aromatic rings
- NaOH: Neutralizes excess acid and facilitates color change in the solution
- Principle: Nitration of aromatic rings leads to the formation of nitro derivatives, producing a yellow-colored product
- Result:
- Positive: Yellow or orange-colored solution indicates the presence of aromatic groups in proteins and amino acids
- Negative: Absence of yellow or orange color indicates the absence of aromatic groups
Learn about the Sakaguchi test, a method used to detect the presence of the amino acid arginine by quantifying guanidinium groups. Understand the purpose of NaOH in making the solution alkaline for the reaction to occur.
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