Enzymes are proteins that have a very specific structure. The region on the surface of an enzyme that is responsible for binding and converting the subtract into the product is called the active site.
Each enzyme works on a particular type of substrate i.e. cellulase works on cellulose. The way that the enzyme and substrate fit together is by the the substrate attaching itself to the enzymes activation site. The size and shape of the activation site depends on what substrate the enzyme works on.
If you're in Biology, you can find this on page 162 :P
Enzymes and substrates will bind together to catalyse chemical reactions. The spot on the enzyme where the substrate will bind is called the active site of the enzyme. The enzyme and the substrate are usually a pretty close fit, hence the naming of the induced fit model.
matching of enzyme with the substrate
The substrate fits inside the active site of the enzyme. when it fits perfectly its called " lock and key"
The substrate fits into the enzyme, much the way a key fits in a lock. Sometimes there are other "modulators" that also fit in the enzyme.
Lock and key is an analogy of enzyme catalysis in a cellular reaction. The lock and key are compared directly to the substrate and enzyme, because of the high specificity of their physical shape. Enzymes participate in the reaction they catalyze. The reactant molecule (substrate) binds to the enzyme molecule at a particular location called the active site. (this is compared to the lock with keyhole) The highly specific nature of an enzyme is due to very precisely defined arrangement of atoms in the active site(again, this is the lock in the analogy). The substrate molecule must have a matching shape (here is the key) that will fit into the active site. The bond breaking and bond forming processes that transform the substrate into products occur while the substrate is bound to the active site of enzyme. In other words its something like a jigsaw puzzle where the substrate fits into the enzyme. The reaction occurs and the substrate then leaves the enzyme as products. ( Not my work. Found it on Yahoo Answers.....Do not give me credit...Thought I should do this to help people out =] ) Edited answer for readability and clarity - thanks!
The lock and key model means that the substrate must perfectly fit the enzyme, and the enzyme does not change. The induced fit model is different as when the substrate fits together with the enzyme, the enzyme itself will change to either join substrates together or break a substrate down.
Enzymes have an active site that is specific for a substrate - therefore enzymes only work when the right substrate is present. The surfaces of the enzyme and the substrate fit together - like a lock and key - allowing the enzyme to fulfil its function. The theory of "induced fit" is more widely accepted - it is similar, but the enzyme shape changes to accommodate the substrate.
An enzyme is shaped so that a specific substrate can attatch to it. A lock and a key function in a similar way. Each lock is shaped so that only a certain key can open it.
There is an enzyme explanation whose specificity states that an enzyme and its substrate possess specific complementary geometric shapes that fit exactly into one another. This is the lock and key explanation.Ê
Today
lock-and-key model
Enzymes and substrates will bind together to catalyse chemical reactions. The spot on the enzyme where the substrate will bind is called the active site of the enzyme. The enzyme and the substrate are usually a pretty close fit, hence the naming of the induced fit model.
matching of enzyme with the substrate
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.
The lock is the equivalent to that of an enzyme while the key is portrayed as the substrate. Like an enzyme, the lock can be reused many times as it remains chemically unchanged at the end of the reaction. Also, the fact that reactions occur only at the active site, or binding site, is showed as the key only being able to open the lock only at the keyhole, not anywhere else. The hypothesis also shows the fact that enzymes can only catalyse a specific substrate, showed as the lock, only being able to open with a specific key. Firstly,the substrate will enter the active side of the enzyme.then,the enzyme will change it shape slightly as the substrate binds.During this time,the substrate will be broken down.After that,the product will leave the active sides of the enzyme.
The substrate fits inside the active site of the enzyme. when it fits perfectly its called " lock and key"
An enzyme has only one substrate that it works with so it has only one function. This is called a lock and key mechanism. Other things can affect the enzyme such as temperature, pH level and levels of either the substrate or the products. High temperature can denature the enzyme (they are proteins). They can not fit the lock (substrate).