 QUALITATIVE ANALYSIS OF AMINO ACIDS AND PROTEINS

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IX.WEEK

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9th WEEK

 QUALITATIVE ANALYSIS OF AMINO ACIDS AND PROTEINS

 Explanation of qualitative observation principles

 Ninhydrin test, xanthoprotein assay, qualitative biuret test

 Test observations and results report

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QUALITATIVE ANALYSIS

 Qualitative (quantitative) analysis; is an analysis made to

understand what the substance is. The branch of analysis,

which examines what element or compounds a substance

is composed of in chemistry, is called quantitative, and the

branch of analysis, which examines what each of these

elements or compounds are, is also called quantitative.

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QUALITATIVE ANALYSIS

 In general, these two concepts can be easily confused

because they are expressed in similar words. In qualitative

analysis, when the quality of the substances is taken into

consideration, in quantitative analysis, the quantity of

substances is examined.

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Ninhidrin experiment



Ninhydrin is an organic oxide. Amino acids undergo oxidative deamination and decarboxylation by the action of ninhydrin. The reduced ninhydrin reacts with the free ammonia to form a blue-violet complex.



Amines other than amino acids react with ninhydrin by forming a blue color without forming CO2. Therefore, the formation of CO2 indicates the presence of an α-amino acid. NH3 and peptides also react with ninhydrin, although they are slower than amino acids.



Imino acids (proline and hydroxy proline) react with ninhydrin and produce a yellow condensation product.

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Xanthoprotein assay

 The xanthoprotein reaction is formed by the amino acids phenylalanine, tyrosine and tryptophan that are present in proteins and carry the phenyl ring in the structure. When nitro groups are introduced into the phenyl ring, yellow-colored compounds are formed, with the addition of alkali, these compounds are converted to orange-colored salts.

 In the protein solution, a white colored precipitate is formed; this is converted to a yellow compound when heated. When alkali is added to the solution, it is observed that the color changes to orange. This color is a variable color.

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 The students will be able to apply the knowledge acquired during the previous week.

 In this context, students will be organized into groups of three before the study.

 Ninhydrin and xanthoprotein assays will be required from each group.

 All consumables, chemicals, laboratory equipment,

especially glassware, and machinery and equipment will be

provided as required.

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 It will be reminded that each student will be responsible for the issues given to all other groups within the application.

 Students will be asked to report their

observations and results within the scope of

the application to the test report

immediately given to them at the end of

their applications.

(9)

 QUALITATIVE ANALYSIS OF AMINO ACIDS AND PROTEINS

IX.WEEK

9th WEEK

 QUALITATIVE ANALYSIS OF AMINO ACIDS AND PROTEINS

 Explanation of qualitative observation principles

 Ninhydrin test, xanthoprotein assay, qualitative biuret test

 Test observations and results report

QUALITATIVE ANALYSIS

 Qualitative (quantitative) analysis; is an analysis made to

understand what the substance is. The branch of analysis,

which examines what element or compounds a substance

is composed of in chemistry, is called quantitative, and the

branch of analysis, which examines what each of these

elements or compounds are, is also called quantitative.

QUALITATIVE ANALYSIS

 In general, these two concepts can be easily confused

because they are expressed in similar words. In qualitative

analysis, when the quality of the substances is taken into

consideration, in quantitative analysis, the quantity of

substances is examined.

Ninhidrin experiment

Ninhydrin is an organic oxide. Amino acids undergo oxidative deamination and decarboxylation by the action of ninhydrin. The reduced ninhydrin reacts with the free ammonia to form a blue-violet complex.

Amines other than amino acids react with ninhydrin by forming a blue color without forming CO2. Therefore, the formation of CO2 indicates the presence of an α-amino acid. NH3 and peptides also react with ninhydrin, although they are slower than amino acids.

Imino acids (proline and hydroxy proline) react with ninhydrin and produce a yellow condensation product.

Xanthoprotein assay

 The students will be able to apply the knowledge acquired during the previous week.

 In this context, students will be organized into groups of three before the study.

 Ninhydrin and xanthoprotein assays will be required from each group.

 All consumables, chemicals, laboratory equipment,

especially glassware, and machinery and equipment will be

provided as required.

 It will be reminded that each student will be responsible for the issues given to all other groups within the application.

 Students will be asked to report their

observations and results within the scope of

the application to the test report

immediately given to them at the end of

their applications.

 Students will be asked to remove any material they use, and if necessary, they will be expected to help with cleaning.

 Laboratory safety and cleanliness will be

allowed to come out after they are provided.