Nicola Perscheid [Public domain], via Wikimedia Commons

Enzymes - Who’s this dude?

- Hermann Emil Fischer.

- Never heard of him.

- He won the Nobel Prize in 1902.

- OK That’s pretty cool. Why?

- For his work on sugar and purine synthesis.

- Nice… But the title of this sheet is enzymes.

- Yeah, he also worked with them too. In 1894 he wrote:

“Um ein Bild zu gebrauchen, will ich sagen, dass Enzym und Glucosid wie Schloss

und Schlüssel zu einander passen müssen, um eine chemiache Wirkung auf

einander ausüben zu können.”

- I don’t speak German.

- Fine. I’ll translate:

“To give an illustration I will say that enzyme and glucoside must fit together like

lock and key in order to be able to exercise a chemical action on each other.

- So he came up with the ‘lock & key hypothesis’, nice… Question: Is the enzyme

the lock or the key?

- Not sure...

The Lock and Key Hypothesis Task: Using the information provided decide if the enzyme should be described as the lock or the key in the lock and key hypothesis

What are enzymes? Globular proteins Biological catalysts They do not change after the reaction They are found in small quantities The are specific, they only work on one reaction

The reactions are reversible

How Enzymes Work

Enzyme Action Enzymes work on specific substrates Substrate(s) have to fit in the active site

Enzyme Structure 3D Structure of an enzyme determines its unique shape. Forms the active site If the active site gets deformed by high temperatures or pH

changes then the enzyme won’t work, it has become denatured

Some molecules are inhibitors, they fit into the active site and prevent the reaction from occurring

They are large molecules usually much larger than their substrates