It is when the enzyme (lock) fits exactly into the substrate (key) forming an enzyme substrate complex.
It refers to enzymes and their substrates. The enzyme has an active site (lock) where the substrate that is complemetary fits in (key). Only substrates that fit perfectly into the enzymes active site will active the particular reaction, just like only 1 specific key will open a door.
An example of the induced fit theory is when an enzyme undergoes a conformational change to better accommodate the substrate upon binding. On the other hand, the lock and key theory suggests that the enzyme's active site is already in the correct shape to fit the substrate like a lock and key.
Lock and Key hypothesis
lock and key theory
The lock and key theory and the induced fit theory are two theories that explain enzyme specificity. The lock and key theory proposes that the enzyme's active site is already in the correct shape to bind the substrate, like a key fitting into a lock. The induced fit theory suggests that the active site of the enzyme can change its shape slightly to accommodate the substrate, similar to a glove molding around a hand.
The key and lock theory suggests that enzymes and substrates fit together like a key fits into a lock with a rigid, non-flexible active site. In contrast, the induced fit model proposes that the enzyme's active site can change its shape to accommodate the substrate, thus providing a more dynamic interaction between the enzyme and substrate.
The key may not come out of the lock due to a misalignment of the key or the lock mechanism, a damaged key or lock, or debris blocking the key's removal.
To unlock a bike lock with a key, simply insert the key into the lock and turn it in the direction that opens the lock. Make sure to use the correct key that matches the lock.
The key may be stuck in the lock due to a misalignment of the key or the lock mechanism, dirt or debris obstructing the keyway, or wear and tear on the key or lock.
A key, or a Combonation
The lock and key theory of enzyme-substrate binding does not account for the induced fit model, where the enzyme and substrate can undergo conformational changes to better fit each other. It also does not explain the binding of substrates that are larger than the active site or the ability of enzymes to catalyze multiple types of reactions.
A key lock works by putting a key in and when you turn the key it pushes a loose round piece which releases the lock.
lock key