Enzymes Enzyme Action Factors Affecting Enzyme Action 1

2 Remember :  Large particles cannot be absorbed in the small intestine starch G G G GUT INSIDE THE BODY (BLOOD) Large particles (e.g. starch) are left in the gut and small particles (e.g. glucose) go through into the blood. G G G BUT large particles can be broken down into small particles. This is called DIGESTION

 Digestive enzymes speed up the process of hydrolysis. Enzymes are biological catalysts.  All enzymes are protein in nature.  They are ORGANIC CATALYSTS that ___________________ and _______________ chemical reactions without being used up in the process.  This means they remain unchanged by the reaction and can be used ______ and _________; A small amount of enzyme can catalyse a _________________ many times, processing a lot of substrate. 3 SPEED UPCONTROL OVER REACTION

 An enzyme is very specific to the substrate upon which it acts, e.g. The enzyme sucrase will only act upon sucrose to form glucose + fructose (the products). It will not act on any other substrate.  Enzyme reactions are ________________ - they work in both directions.  They work very rapidly. Enzymes are sensitive to high ____________  Enzymes are sensitive to _________ changes. 4 REVERSIBLE Extreme changes in these cause _____________ TEMPERATURE pH DENATURATION

 The activation energy which is required to hydrolyse sucrose into its monomers during digestion is indicated in the following graph as X. 5 BIOLOGICALLY EFFICIENT Which curve represents the activation energy for this reaction to take place when the required enzyme is added? Provide a reason for your answer.______________________ C – LOWERS AMOUNT OF FREE ENERGY NEEDED AND SPEEDS UP THE REACTION

 The shape of enzyme is critical - it must fit exactly into the _____________________ shape of the substrate molecule to cause the reaction. This is why denaturing is so harmful.  This shape on the surface of the enzyme is called the ______________________  When the substrate and enzyme have locked together, this forms an  ___________________________________________________  After the reaction, it becomes an _______________________________________. and thereafter they separate and the enzyme moves to the next reaction. 6 ACTIVE SITE COMPLIMENTARY TEMPORARY ENZYME-SUBSTRATE COMPLEX ENZYME-PRODUCT COMPLEX

7

+ + E + S ES complex E + P 8 S P P S HYDROLYSIS CONDENSATION

9 Active site: complimentary to the shape of the substrate P + Q = SUBSTRATE ENZYME-SUBSTRATE COMPLEX N = ENZYME M = PRODUCT

 Which letter represents the enzyme? Give ONE reason for your choice. _______________________________________________________  Name two factors that can influence the above reaction.  _______________________________________________________  Which one of the following (X, Y or Z) can be represented by the above reaction?  Xcondensation of two glucose molecules to form sucrose.  Yhydrolysis of sucrose to form glucose and fructose  Zcondensation of two different amino acids to form a dipeptide. ________________  Explain why the other two alternatives are not correct.  _______________________________________________________  10 N – contains complimentary active site for substrates TEMPERATURE pH Z X – THE SUBSTRATE MOLECULES ARE DIFFERENT AND 2 GLUCOSE WILL BE IDENTICAL Y – THIS IS NOT AN HYDROLYSIS WHERE THE SUBSTRATE IS BROKEN DOWN. IT IS A CONDENSATION

The effect of temperaturechange and enzyme activity: 11

 The particular temperature at which an enzyme acts best is known as its __________________________________________. This temperature is ____________  At temperatures lower than the optimum, the enzyme remains ________________ because they lack _________________.  As temperature increases up to the optimum temperature, the enzyme activity ___________________ and then stops as the enzyme starts ________________________.  A denatured enzyme loses its shape and hence its specifically shaped _________________________________________. 12 OPTIMUM TEMPERATURE 37,5 O C INACTIVE ENERGY INCREASES DENATURING ACTIVE SITE

pH- the amount of H + ions in a solution. ACID extra H +1 ions (protons) BASE fewer H +1 ions. extra OH +1 ions. Whatchyall lookin at bra ?

The effect of pH change on enzyme activity: 14 RENNINRESPIRATORY ENZYME LIPASE

 Enzymes work: at their best at a specific pH called the ____________________  pH changes in BOTH directions away from the optimum pH cause the enzyme to become _______________________ - the _______________________ is damaged and can no longer fit the substrate, so it cannot function. 15 OPTIMUM pH DENATURE ACTIVE SITE

 Some enzymes can only 'work in the presence of a co- factor. A co-enzyme is an organic, non-protein co-factor that works with the enzyme. "They usually transfer chemical groups from one enzyme reaction to the next, such as carrying hydrogen atoms during cell respiration. Vitamin ______ is a co-enzyme during cell respiration, so it is critical for optimal energy release from food that we take in enough of it, or take supplements during times of stress. 16 B3B3

Catalase enzyme in potato acts on Hydrogen peroxide H 2 O 2 What’s going on? 1. The enzyme in a potato Catalase enzyme in potato H 2 + O 2 Hydrogen peroxide Hydrogen gas + Oxygen gas Catalase decomposes hydrogen peroxide into …

3.1 What is the effect of pepsin on egg-white? (2) 3.2In which test tube/s will there be a result? (2) 3.3Give a reason for your answer. (3) 3.4Explain why there will not be result in the other test tube/s (if there are any). 3.5 What result will be observed? (3) 18 DIGESTS PROTEINS INTO POLYPEPTIDES TT3 HCl (ACID), EGG WHITE (SUBSTRATE) AND PEPSIN (ENZYME) 1 – NO HCl; 2 – NO ENZYME, 4 – ENZYME DENATURED BY BOILING IN TT 3 – PIECES OF EGG WHITE DISAPPEAR AND A CLOUDY SOLUTION RESULTS, AS PROTEIN IS DIGESTED

1. Name the alcohol produced in the making of wine. _____________________(1) In which starchy product is the same alcohol formed, but lost during the baking process? _______________________ (1) 2Why is it not possible for natural fermentation to increase the alcohol content of a fermented product to 20% or more? (2) 3Name the enzyme used in making soft-centred chocolates. ____________ (1) 4Name three dairy products made using enzymes. _________________________ ___________ (3) 19 ETHANOL BREAD YEAST DIES WHEN IT REACHES 18% SUCRASE CHEESE, MILK, YOGHURT

5 Why is rennin/rennet used in cheese making?______________________________ (2) 6Why is it necessary to denature whey proteins when making yoghurt (1) 7Which enzymes are used to give jeans a “stone-washed” look? (1) 1. Why is it better to use enzymes than real stones in the above case? Give two reasons. (2) 8 State one specific use of the enzyme ‘isomerase’. _________________________ Why does the use of this enzyme make sense here? (2) 9What is pectin? 10Suggest why pectinase can make fruit juice clearer. (2) 20 It coagulates/clots milk IT MAKES THEM CREAMIER CELLULASE ECONOMIC: ENZYMES MORE EASILY SOURCED. FASHION: DOES NOT DAMAGE JEANS CHANGES GLUCOSE INTO FRUCTOSE FRUCTOSE SWEETER, LESS NEEDED, USED IN SLMMNG FOODS POLYSACCHARIDE FOUND IN MIDDLE LAMELLA BREAKS DOWN THE PECTIN AND REMOVES THE PULP

11.2Name the enzyme, which was effective in this experiment. (2)  ______________________________________________ 11.3What was found to be the most suitable temperature for the action of this enzyme? (2)  _______________________________________________ 11.4 What indicator would you have used to show the presence of starch? (2)  ___________________________________________________ 11.5 How long would you expect digestion to have taken place in a similar test conducted at 22,5 0C? (Indicate how you found this on the graph) (2) 21 AMYLASE 35 O C IODINE 48 SECONDS

11.6 Name the end-product of the digestion of the cooked starch. (2) _________________________________________ 11.7 Name TWO other factors affecting enzyme efficiency which could be tested by similar experiments. (2) 1. _______________________________________ 2. _______________________________________ 22 GLUCOSE AMOUNT OF SUBSTRATE or pH AMOUNT OF ENZYME