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Lock and Key Theory: The specific action of an enzyme with a single substrate can be explained using a Lock and Key analogy first postulated in 1894 by Emil Fischer. In this analogy, the lock is the enzyme and the key is the substrate. Only the correctly sized key (substrate) fits into the key hole (active site) of the ...


The lock-and-key model refers to the way in which a substrate binds to an enzyme's active site. Similar to how a key has to be the correct one for a lock, no reaction takes place if an incorrect substrate tries to bind. The active site of an enzyme is a specific region that receives the substrate. It possesses a unique shape that complements ...


Lock and Key Hypothesis. In order to explain why enzymes have such a high level of specificity, Emil Fischer in 1894 suggested that both a substrate and an enzyme have specific geometric shapes that fit exactly into each other. This idea of both substrates and enzymes having a natural geometric fit has been called the lock and key hypothesis.


Figure 18.11 The Lock-and-Key Model of Enzyme Action (a) Because the substrate and the active site of the enzyme have complementary structures and bonding groups, they fit together as a key fits a lock. (b) The catalytic reaction occurs while the two are bonded together in the enzyme-substrate complex.


Enzymes are biological catalysts which speed up reactions. They are specific for their substrate. The lock and key hypothesis models this. Enzymes are denatured at extremes of temperature and pH.


In the lock-and-key model of enzyme action, the enzyme active site is thought of as a rigid, nonflexible shape that fits the substrate exactly. In the induced-fit model of enzyme action, the enzyme active site


What is Lock and Key? Lock and Key is one of the theories that explain the mode of action of an enzyme which catalyzes a reaction. Emil Fischer proposed this theory in 1894. According to lock and key hypothesis, the binding of the substrate into an active site of an enzyme is equalized into the lock and key mechanism.


Explain the Lock & Key Model of Enzyme Reactions. Your body requires enzyme reactions as catalysts to maintain life. The action of carbonic andydrase, for example, accelerates the movement of carbon dioxide from body cells into the blood by speedily converting carbon dioxide and water into bicarbonate ions, ...


Consequently, an enzyme reduces the activation energy of biological reaction, which it catalyzes. Two main theories are used to explain how enzyme-substrate complexes form. They are lock-and-key theory and induced-fit theory. Lock-and-Key Model. Enzymes have very precise shape, which includes a cleft or pocket called active sites.


The basic theory behind the lock and key model, the idea that substrates have to fit the enzyme, is still the same, but in the induced fit model the active site is simply less rigid.