Enzymes

[rach_liz]

In terms of molecular structure, why won't biological washing powder containing enzymes break down oily stains? (It's for AS level homework!)

[Gef]

Do you mean stains caused by food or by hydrocarbons?

[Peter Pedant]

because the enzymes in soap are not lipases

( I was gonna say because the C-H and C-C bond energy is too high for a protein to break but I think that is almost certainly untrue)

[badgerxx]

Biological washing powders contain lipase and protease enzymes to make fats and proteins water soluble. They do this by hydrolysing those molecules (causing a chemical reaction to occur on the target molecules which causes the addition of -OH groups to it). The more -OH groups you can add, the more water soluble the lipid becomes as the -OH groups are attracted to the OH group in the water molecule by dipole-dipole interaction and hydrogen bonding.

They work by being able to bind to the target molecule, or sites on that molecule. This depends on the size and shape of the target molecule as well as its chemical compsoition. Hydrocarbon oily stains are made up of molecules which do not "fit" together with the enzyme, so the enzyme cannot alter the chemical characteristics of the target molecule to allow it to undergo hydrolysis.

[rachael122]

I think it means hydrocarbon chains, and thankyou badger person for your answer!