Unit 4: Enzymes

It is Just Chemistry…Really FAST Chemistry

• All living things require chemistry to exist:– Photosynthesis (making sugars)– Glycolysis (breaking sugars)– Making ATP (energy units)

• How long does it take for a chemical reaction to occur in a living thing?– 2.3 billion years

• How long does the same reaction take with an enzyme?– Less than 1 second

• Life CANNOT exist without enzymes4.5 billion years

What is an Enzyme?• Biological catalysts a catalyst

used in biochemistry• Catalyst a substance that

speeds up a chemical reaction but is NOT affected by it– Never changed so it cannot be

used up– Can reach a limit on how fast they

can work• Enzymes are made of proteins– Few made from RNA (ribosome)

What do Enzymes do?• 10,000s of enzymes in a cell1) Anabolic enzymes:• Build complex molecules– Photosynthesis changes CO2 into C6H12O6

(sugar)2) Catabolic enzymes:• Break apart complex molecules– Glycolysis breaks sugar apart to make ATP

(energy units)3) Transformation enzymes:• Change one substance into another

substance– Yeast add H+ to compounds to make

alcohol

Enzyme Structures• Lock and Key Model:• Substrate substance the enzyme is

designed for (Key)• Enzyme binds with substrates to

combines them, break them apart, or change them (Lock)

• Active site site in enzyme that is designed to match the shape of the substrate (Key Hole)

• The Key (substrate) fits in the Lock (enzyme) by entering the Key Hole (active site)

• Only if the Key (substrate) fits the Key Hole (active site) will the Lock (enzyme) work

Enzymatic Rates• Enzymes can be used over and

over; only a few enzymes are needed to react with lots of substrate

• How can we increase the reaction rate?– Add more enzymes (share the work)

• Why does this rate stop increasing?– Enzyme can only work so fast– It takes time to do each reaction– All enzymes have a maximum

efficiency

Enzymatic Rates: Temperature• What drives enzymatic rates?– Kinetic energy

• Kinetic energy random movement in all atoms– Substrates and enzymes

randomly move around and eventually join together

• How can we increase kinetic energy in atoms?– Give them more energy by

increasing temperature

Optimum Temperature• All enzyme reactions slow down at low

temps and increase at higher temps• What happens when the temperature gets

too high?– Enzyme stops working (denatures)

• Protein bonds chemical bonds making holding the enzyme in a specific shape– High temps break these bonds; enzyme unfolds

and cant work (denature)• Optimum temperature the temp. an

enzymatic rate is highest without denaturing the enzyme– Fungi and plants 40 oC– Humans 37 oC– Some bacteria 90 oC

Optimum pH• pH can affect the peptide bonds of

an enzyme too• Optimum pH the pH where the

enzymatic rate is highest without denaturing the enzyme– Varies greatly in the body

• Blood pH = 7.4• Stomach pH = 2

• If you fix the pH and temp. of a denatured enzyme, can it be used again?– Sometimes. Some proteins can

renature. Most proteins cannot.

The Properties of Enzymes• 5 Major Properties:1) Enzymes are made of proteins2) Enzymes catalyze one specific reaction3) Enzymes, being catalysts, can be reused

many times4) Enzymes are influenced by temperatures

(all have an optimum temperature) 5) Enzymes are influences by pH (all have an

optimum pH)

Using Enzymes• Enzymes from living things can be

used in production:– Medicine– Food– Fuel– Materials

• General types:1) Proteases break apart proteins2) Lipases break apart fats3) Amylases break down sugars4) Cellulous break down cellulose

(cell wall)

Making Medicine• Penicillin is an antibiotic that can kill

many types of bacteria– Fungi Penicillium makes it through

fermentation (breaking down sugar without Oxygen)

• Fermentation Process – Penicillium added to large vessel full of

sugar and nutrients– Stirrer mixes up insides– Water-cooled jacket keeps vessel at 24

oC– Probes keep pH at 6.5

• After 6 days of this, penicillin can be drained from mixture

• Cleaned and sent to hospitals

Homework• Study to Exam on Units 1-4

on 10/8• Cell Projects due 10/11• Quizlets for Units 3 and 4• Homework papers on Unit

2, 3, and 4