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Biochemistry - Laboratory > Color Reaction of Proteins > Flashcards

Color Reaction of Proteins Flashcards

1
Q

essential constituents of the living cells, are hgih molecular weight compounds which, upon hydrolysis, produce amino acids

A

proteins

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2
Q

proteins, constituents of the living cells, are hgih molecular weight compounds which, upon hydrolysis, produce

A

amino acids

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3
Q

in a protein, amino acids are linked by

A

peptide bonds

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4
Q

GENERAL TESTS FOR COLOR REACTIONS OF AMINO ACIDS

A
  • Biuret Test
  • Ninhydrin Test
  • Folin’s Test
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5
Q

a general test for proteins comparable to Molisch’s Test for carbohydrates

A

Biuret Test

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6
Q

what color appears when Biuret’s reagent is added to any compound which contains 2 or more of the following groups which all contain the -CO - NH2 groups

A

a violet color

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7
Q

if the biuret test is negative, the color is

A

blue

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8
Q

if the biuret test is positive, the color is

A

violet/deep purple

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9
Q

(Ninhydrin Test) in the presence of strong alkalies and of amino acid ___________________________________________ develops a striking, deep red color

A

beta-naphthoquinone

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10
Q

(Ninhydrin Test) __________________________________________________________________________ do not yield colors

A

urea, uric acid, creatinine and hippuric acid

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11
Q

ninhydrin test show positive test for:

A

alpha amino acids and proteins that contain free amino acid groups

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12
Q

a positive ninhydrin test is indicated by:

A

the formation of red, blue, or purpple color

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13
Q

folin’s reagent or sodium 1, 2-napththoquinone-4-sulfonate is a chemical reagent used as a derivatizing agent to measure levels of amines and amino acids

A

folin’s reagent

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14
Q

folin’s reagent or

A

sodium 1, 2-napththoquinone-4-sulfonate

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15
Q

SPECIFIC TESTS FOR COLOR REACTIONS OF AMINO ACIDS

A
  • Millon’s test
  • Xanthoproteic Test
  • Hopkins-Cole Test/Trytophan Reaction
  • Reduced Sulfur Test
  • Sullivan Cystine Reaction
  • Diacetyl Test
  • Nitroprusside Reaction
  • Bromine-Water Reaction
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16
Q

a test for the presence of a phenolic ring, as in tyrosine which gives a red color with reagent made by dissolving mercury in nitric acid

A

Millon’s test

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17
Q

is made by dissolving metallic mercury in nitrous acid and diluting with water

A

Millon’s Reagent

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18
Q

Millon’s test was developed by the French chemist

A

Auguste Nicolas Eugene Millon

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19
Q

is not only speficic for proteins; it also gives a positive test for other compounds containing the phenol functional group

A

Millon’s Test

20
Q

it directs the presence of benzene rings on which there are amino groups or hydroxyl groups which are easily nitrated to give yellow-colored aromatic nitro compounds

A

Xanthoproteic test

21
Q

is used to detect amino acids containing an aromatic nucleus in a protein solution which gives yellow colored nitro derivative on heating with conc. HNO3.

A

Xanthoproteic Test

22
Q

amino acids containing an aromatic nucleus

A

tyrosine, tryptophan, and phenylalanine

23
Q

When tryptophan or containing tryptophan is heated with strong sulphuric or hydrochloric acid in the presence of aldehyde,

A

a blue or violet color is produced

24
Q

Many proteins give the test without the addition of an aldehyde, owing either to contaminations or to the presence of carbohydrate units in the protein
molecule

A

Leibermann Reaction

25
Q

When formaldehyde is added

A

Acree-Rodenheim Reaction

26
Q

Glacial acetic is employed because it contains glyoxalic acid, COOH-CHO.

A

Adamkiewicz Reaction

27
Q

P-dimethylaminobenzaldehyde is used

A

Ehrlich Reaction

28
Q

employs the unsubstituted benzaldehyde

A

Cole’s Test

29
Q

uses performed glyoxalic acid

A

Hopkin’s-Cole Test

30
Q

A test for sulfur – containing amino acids cysteine and cysteine (except for methionine where its sulfur is not reactive), which react with acetate to form black lead sulfide

A

Reduced Sulfur Test

31
Q

Darkening of the medium (a black precipitate) or blackening of the line of inoculation indicates the presence of bacteria producing hydrogen sulfide.

A

Positive Reduced Sulfur Test

32
Q

is denoted by the absence of blackening

A

Negative Reduced Sulfur Test

33
Q

No black precipitate formed

A

H2S-NEGATIVE

34
Q

Black precipitate formed

A

H2S-POSITIVE

35
Q

Is a chemical test used for detecting the presence of cysteine or cystine in proteins.

A

Sullivan Cystine Reaction

36
Q

Sullivan Cystine Reaction is pioneered by the American Organic and Industrial Chemist

A

Eugene Cornelius Sullivan

37
Q

Appears when a protein with cysteine or cystine is heated with sodium 1,2- naphthoquinone-4-sulfonate (Folin’s Reagent) and sodium dithionite under alkaline conditions

A

red color

38
Q

Is specific for arginine because this reaction is given by guanidinium compound

A

Sakaguchi Test

39
Q

The arginine reacts with alpha-naphthol and an oxidizing agent such as bromine water or sodium hypochlorite/sodium hypobromite to create a red colored product

A

Sakaguchi Test

40
Q

Positive Sakaguchi Test:

A

red color

41
Q

Negative Sakaguchi Test:

A

No red color

42
Q

Diacetyl Test or

A

Voges-Proskauer (VP) Test

43
Q

Is used to determine if an organism produces acetylmethyl carbinol from glucose fermentation.

A

Diacetyl Test

44
Q

Positive Diacetyl Test

A

a pink-red color at the surface

45
Q

Negative Diacetyl Test

A

a lack of pink-red color

46
Q

Proteins containing cysteine give a reddish color with sodium nitroprusside in dilute ammoniacal solution. This reaction is due to the presence of the SH group.

A

Nitroprusside Reaction

47
Q

Tryptophan gives a pink color hen treated with bromine water

A

romine-Water Reaction

Biochemistry - Laboratory (5 decks)

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