Question

What do enzymes do in biochemical reactions?

Answer 1

The problem with biochemical reactions is that they don't occur quickly enough. For the reactants in a reaction to form products, they have to change their structures - that is, they pass through a series of intermediate shapes as they change.

These intermediates are quite high energy, meaning they are very unlikely to form given the low energy available in biologic systems. The energy level of the intermediates is called the activation energy.

Enzymes bring reactants together in a specific orientation so their reactive groups are arranged in a way that makes a reaction much more likely. That is, they lower the activation energy required for the reaction to take place.

Just like any normal catalyst. Hope that's helpful.

Answer 2

Do they bind to other reactants or to ATP?

Answer 3

Usually enzymes do not form covalent bonds with their substrates - at least not in the initial reactant binding step. Most of these interactions are weaker non-covalent ones, but there are many of them so the many small interactions add up. Sometimes during the reaction, some enzymes will form a covalent bond with the intermediate structure - but that is the exception rather than the rule.

Yes, ATP is a very common substrate of enzymes.

Answer 4

In fact, the ATP binding enzymes are sometimes called ATPases or have an ATPase domain which binds ATP while the rest of the enzyme binds other things.

Answer 5

Thanks that was helpfull!

Answer 6

Blues posted a very exquisite answer, i couldn't help myself from attaching a related picitured i spent a good 10 minutes laughing at. It's ontopic.

Answer 7

Teeheehee - The one thing is that's one reaction which is definitely not spontaneous...