Qualitative reaction to adrenaline.

The pyrocatechin structure is the basis of the chemical structure of adrenaline. Biosynthesis of adrenaline occurs in the adrenal medulla from the amino acid tyrosine. Injection of adrenalin in the body causes hyperglycemia, glucosuria, increased concentrations of free fatty acids in the blood, increasing and strengthening of the heartbeat, high blood pressure.

The reaction to adrenalin with chloride iron (III).

In one test tube add 0.5 ml of pyrocatechin, in the other – 0.5 ml of adrenaline. In each test tube add 2 drops of 1% solution of iron chloride (III). The liquid in the test tube takes the green color, gradually turning into yellowish. Reaction is due to the presence of pyrocatechin group in a molecule of adrenaline.

The reaction to adrenaline with potassium iodide.

To 0.5 ml of adrenaline add 1 ml of 1% potassium iodide solution, 10 drops of 10% acetic acid solution. Mixture is heated slightly. There is an intense red-violet color. The chemistry of the reaction is unknown.

The reaction with nitrite-molybdenum reagent.

In the test tube 0.5 ml of an aqueous solution of adrenaline is poured, 0.5 ml of 5% hydrochloric acid solution, 1 ml of nitrite-molybdenum reagent. The mixture is stirred. There is a yellow-orange color. After adding a few drops of 10% sodium hydroxide solution crimson-red color appears, turning in the lemon-yellow after adding a few drops of concentrated hydrochloric acid.

Diazoreaction.

Pour 0. 5 ml of 1% sulfanilic acid solution in the test tube, add 0,5 ml of 5% sodium nitrite solution, 1 ml of adrenaline and 0,5 ml of 10% sodium carbonate solution. In the interaction of adrenaline with diazoreagent products of the red color are formed.

Qualitative reactions to insulin.

Insulin is produced by β-cells of Langerhans islets of the pancreas. It is a protein composed of two polypeptide chains connected by two disulfide bridges. Insulin increases the permeability of cell membranes for glucose, activates the liver hexokinase synthesis, increases the synthesis of glycogen and fat from glucose, inhibits oxidation of fatty acids and gluconeogenesis. It causes hypoglycemia. Lack of insulin in diabetes leads to hyperglycemia. Insulin can be detected by reactions which are characteristic for proteins.

Biuretic reaction.

To 1 ml of insulin solution add 2 ml of 10% sodium hydroxide solution and 2 drops of 1% copper sulphate solution and stir. A red-violet color appears.

2.2. Millon’s reaction.

Pour 0,5 ml of insulin solution is the test tube, add 3 drops of Millon reagent. There is a white precipitate. At low heat precipitate at first colored in pink, then red.

The mercury salt of tyrosine nitro derivative is formed.

2.3. Foll’s reaction.To 1 ml of insulin solution add 2 ml of concentrated sodium hydroxide solution and boil for 1-2 minutes. Add 1 ml of 10% lead acetate solution. Brown-black color appears.

2.4. Geller’s test.

In the test tube pour 0,5 ml of concentrated nitric acid and by tilting the tube, carefully pour in a wall equal volume of insulin solution. A white amorphous precipitate of protein in the form of a ring appears in the place of contact between two liquids. Gently shake the test tube and add an excess of nitric acid. Precipitate doesn’t disappear.

Date: 2016-04-22; view: 1159