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Ninhydrine [2,2-Dihydroxyindane-1,3-dione] is equilibrating with [indane-1,2,3-trione] + H2O.
Two molecules of this triketon react each with their number 2 carbonyl in two steps:
- The first step is when a free amino group of the amino acid reacts with it the carbonyl group and gives free H2O, CO2 and a Shiff-base, that will be followed by hydrolysed ( + H2O) an aldehyde and an Amine [2-Amino-indane-1,3-dione]
- In the second step this Amino group gets (again) coupled to a second triketone molecule [indane-1,2,3-trione] and an Imine-di-(Indane-1,3-dione) is formed (with H2O given free).
With proline and hyroxy proline no blue color can be seen due to the fact that the first step will stop right after decarboxylation is completed, because the following hydrolysis of the Schiff-base is NOT possible. It turns yellowish brown instead.
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Give an example of polypeptide?
Protein.
Why ninhydrin shows positive test for amino acid and protein?
Ninhydrin reacts with ammonia, a primary amine, or a secondary amine (amino acids have a primary or alpha amino group, except for proline which has a secondary amino group). They all turn purple/blue right away upon heating with ninhydrin.Remember that a protein has a amino terminal and a -COOH terminal. The ninhydrin will react with the amino terminal giving a very light blue or violet color (more often than not you will see no color change). Upon further heating you may notice an increase in the intensity of the blue/violet. this is due to the heat denaturing the protein, thereby exposing more -NH2 groups for the ninhydrin reagent to react with
Will Alanine give a negative Biuret test?
Because solutions with "free" amino acids don't have peptide bonds and peptide bonds need to be present in order for the test to be positive.
What consist of long chain of amino acids?
Proteins contain long chains of amino acids. The amino acids in protein are what give proteins their high energy content.
What are the names of the two chemical groups that all amino acids have in common?
Amino = Amine Acid = Carboxylic Acid These two groups are what give amino acid's there name. Source: http://en.wikipedia.org/wiki/Amino_acid
What funtional group will give a positive results with ninhydrin reagents?
Amino acids with a free -NH2 group and proteins containing free amino acids
What color develops when ninhydrin react with amino acids?
These are the amino acids that will yield positive result to the ninhydrin test: Non-polar amino acids: Glycine, Alanine, Valine, Leucine, Isoleucine, Phenylalanine, Methionine, Tryptophan Polar Neutral Amino acids: Serine, Cysteine, Threonine, Asparagine, Glutamine, Tyrosine Polar Acidic Amino Acids: Aspartic acid and Glutamic acid Polar Basic Amino Acids: Histidine, Lysine, Arginine
Why proline amino acid gives yellow colour in reaction with ninhydrin?
Yes. Within "The Chemical Reactions of Amino Acids / Reactions of Amino Groups" there are several examples - one of which is the ninhydrin reaction. A very widely applied reaction of the alpha amino group [that is the N in the peptide bond -CCN-CCN-], it is used to estimate the quantity of amino acids [in a sample] in very small amounts. All amino acids and polypeptides with a free alpha group react with ninhydrin and yield [or produce] an intensely purple colored product - except for Proline and Hydroxyproline {both in which the alpha amino group is termed to be 'substituted' - something to do with carbon rings} which "yield derivatives with a characteristic yellow color." See also 'Schiff's bases'.
Give an example of polypeptide?
Protein.
Why ninhydrin shows positive test for amino acid and protein?
Ninhydrin reacts with ammonia, a primary amine, or a secondary amine (amino acids have a primary or alpha amino group, except for proline which has a secondary amino group). They all turn purple/blue right away upon heating with ninhydrin.Remember that a protein has a amino terminal and a -COOH terminal. The ninhydrin will react with the amino terminal giving a very light blue or violet color (more often than not you will see no color change). Upon further heating you may notice an increase in the intensity of the blue/violet. this is due to the heat denaturing the protein, thereby exposing more -NH2 groups for the ninhydrin reagent to react with
Will Alanine give a negative Biuret test?
Because solutions with "free" amino acids don't have peptide bonds and peptide bonds need to be present in order for the test to be positive.
What consist of long chain of amino acids?
Proteins contain long chains of amino acids. The amino acids in protein are what give proteins their high energy content.
Will superpump 250 give a positive drug test?
NO its just caffein and amino acids.
What foods give you amino acids?
Penuts, meat, fish, things with lots of proteins
What amino acids give positive Ehrlich test?
The Ehrlich test is used to determine indoles.
Proteins are made of?
Proteins (also known as polypeptides) are organic compounds made of amino acids arranged in a linear chain and folded into a globular form. The amino acids in a polymer are joined together by the peptide bonds between the carboxyl and amino groups of adjacent amino acid residues. The sequence of amino acids in a protein is defined by the sequence of a gene, which is encoded in the genetic code.Protiens are made up of carbon, hydrogen, oxygen, nitrogen, and sometimes even sulfur.
What makes protiens?
The ingredients of a protein are amino acids. To build a protein we need to build a long chain of amino acids. There are 20 different types of amino acids, so there are lots of different protein chains we can build. Biologists give amino acids a code letter, as for DNA. This is much easier than writing out the whole name each time. For example, Mis methionine, Lis leucine, Fis phenylalanine (because Pis proline).
