WHAT AFFECTS ENZYME ACTIVITY? 1) ORDER OF AMINO ACIDS 2) PROTEIN DENATURATION: When the structure of a protein is changed due to an external stress. If enzyme’s shape is changed  shape of the active site changed  function of the enzyme will change. TEMPERATURE pH 3) INHIBITORS 4) SUBSTRATE CONCENTRATIONS

1) ORDER OF AMINO ACIDS Wrong order = wrong shape = can’t do its job! folded protein active site chain of amino acids DNA right shape! active site shape Changed! DNA wrong shape!

2A) DENATURATION - TEMPERATURE Optimum temperature greatest number of collisions between enzyme & substrate human enzymes: 35°- 40°C (body temp = 37°C) Raise temperature (boiling) denature protein = unfold = lose shape Lower temperature T° molecules move slower fewer collisions between enzyme & substrate

Temperature 37° Optimal Temperature human enzymes reaction rate What’s happening here?! human enzymes 37° reaction rate temperature Not enough heat! Particles move slower  less collisions between enzymes and substrates  less reactions Too much heat! Enzymes denature  active site changes shape  substrate doesn’t fit  less reactions

2B) DENATURATION - pH Effect on rates of enzyme activity changes in pH changes protein shape Denatures most human enzymes = pH 6-8 depends on where in body pepsin (stomach) = pH 3 trypsin (small intestines) = pH 8 Optimal pH Not too acidic and not too basic.

pH 1 2 3 4 5 6 7 8 9 10 11 12 13 14 stomach pepsin intestines trypsin What’s happening here?! reaction rate 1 2 3 4 5 6 7 8 9 10 11 12 13 14 pH Each enzyme has its own optimal pH If too acidic or basic  enzyme denatures  active site changes  no reaction What is pepsin’s optimal pH? __________ Trypsin? ____________

3) ENZYME INBHIBITORS Two kinds of Inhibitors Competitive Inhibitors Enzymes control biochemical processes by increasing the rate at which they occur. Too much activity means– build up can be dangerous to the cell. too much product Enzyme Inhibitors: turns enzymes on or off. Two kinds of Inhibitors Non-competitive Inhibitors - Molecule binds to site other than active site. - Causes enzyme to change shape – substrate can’t bind Competitive Inhibitors - Molecule (not substrate) binds to active site - Blocks substrate

Harmful Enzyme Inhibitors Inhibitors are usually beneficial: they control the rate at which reactions occur No inhibitor: fast Inhibited: slow Some inhibitors are harmful Eg. Nerve Agent – inhibitors that interfere with nerves. First developed in WWII. Eg. Sarin Result? Nerves continuously fire  muscles not able to relax  muscles seize  breathing & heartbeat affected, victim paralyzed. Inhibitor Sarin Competitively inhibits acetylcholinesterase. Enzyme Acetylcholinesterase Responsible for digesting acetylcholine. Substrate Acetylcholine Causes nerves to fire continuously as long as its present.

4) SUBSTRATE CONCENTRATION

Enzymes still available Enzymes occupied Most enzyme’s active sites are occupied, so adding more substrate does not increase reaction rate. Enzymes still available Increasing substrate concentration will increase reaction rate. Saturation Point Point at which all active sites are occupied. What’s happening here?! reaction rate Substrate concentration

HOW TO SPEED UP CHEMICAL REACTIONS (AND GET A DATE) In the video, there are 5 parallels between getting a date and speeding up a chemical reaction. Fill in the following table. Change to School to increase chance of getting a date. Change to variable to speed up chemical reaction. Shrink size of hallways – more chance for students to collide. Increase population of school – more chance for students to collide Increase temperature of a reaction – particles move faster Increase total surface area Hire a matchmaker – makes it easier for a couple to get together by coordinating the match.