Site for children

HomeResearch fun Chemical experimentsEnzymes in saliva



You already have found that saliva is an excellent object for biochemical studies, and, moreover, unlike most other objects of animal origin, continuously available.

In addition to the amylase in saliva, there are other enzymes that help digest food, breaking down complex natural compounds into simpler compounds. But to isolate and study them much harder than amylase. So last our biochemical experiments we will supply with substances of a different nature.

Rinsing the mouth with water, collect approximately 1 ml of saliva in a test tube or vial and dilute triple distilled or boiled water. Pour half of the contents into another test tube and add a drop of about ten drops of a solution of silver nitrate - silver nitrate AgNO3 (can be dissolved in 1 ml of water half lyapisny pencil from the pharmacy; the impurities do not interfere experience). The white precipitate deposited in a test tube, add the vinegar, and the residue partially dissolved. So when interacting with silver nitrate behave salt salt (chloroethanol) and phosphoric acid - chlorides and phosphates.

The second part of the solution saliva slightly pocketlite a weak solution of hydrochloric acid and add a few drops of 3%-aqueous solution of ferric chloride FeCl3. Red-brown coloration indicates that in solution there is Rodney - salt roganisations acid. While in the saliva of smokers little amylase, rhodanides, on the contrary, more than usual. This can be verified experimentally, if you have smokers relatives.

The following experiment will require approximately 5 ml of saliva. Place it in a glass and under stirring with a glass rod, add a few drops of acetic acid (not diluted vinegar, and essences). The wand will attract white ball, similar to cooked egg white. This substance - mucin, it increases the viscosity of the saliva, saguday it and contributes to the formation of foam.

Let's try to understand the composition of mucin. Part of the obtained material, place in a small test tube, drip a little bit, just 2 to 3 drops of nitric acid and wait until the mucin turn yellow. Now put the same amount of concentrated alkali solution (you can take the ammonia solution) and the color will be orange. This reaction is called xanthoproteic, it charakterze for proteins. Instead, you can spend the biuret reaction, described on page "Experiments with protein",and in that and in other case confirmed the protein nature of the substance.

But that's not all. The rest of the mucin isolated from saliva, put the sample on carbohydrates. To do this, use a colored reaction MOLISA described on page "Experiments with carbohydrates", or if you have a bit of L-naphthol, its simplified modification: to a solution of mucin in a weak, about 1%hydrochloric acid, add three to four drops of 0.1%solution of naphthol in alcohol and after stirring very gently drip on the surface of concentrated sulfuric acid. Purple ring will indicate that you have taken for the analysis of carbohydrate.

It turns out that the mucin - protein and carbohydrate at the same time? So. He is from the class of glycoproteins, i.e., compounds containing both protein and carbohydrate part. If you break down his strong acids, are formed amino acids that make up proteins, and carbohydrates.

O. Holguín. "Experiments without explosions"
M., "Chemistry", 1986


Your name (nick):
Enter the result of the calculation

Scientific fun. Home experiments.

  © 2014 All children