Factors that affect enzymes

What are enzymes made of? Enzymes are protein molecules, and so are made up of amino acids. Most enzymes contain between 100 and 1,000 amino acids. These amino acids are joined together in a long chain, which is folded to produce a unique 3D structure.

Why is shape important? An enzyme’s shape is determined by the sequence of amino acids in its structure, and the bonds which form between the atoms of those molecules. Different types of enzymes have different shapes and functions because the order and type of amino acids in their structure is different.

Why are enzymes so specific? Enzymes are very specific about which reactions they catalyze. Only molecules with exactly the right shape will bind to the enzyme and react. These are the reactant, or substrate, molecules. The part of the enzyme to which the reactant binds is called the active site This is a very specific shape and the most important part of the enzyme

TRUE FALSE Enzymes: true or false? Enzymes are proteins. Enzymes are catalysts. The shape of the enzyme is critical to its function. An enzyme’s structure is determined by the sequence of carbohydrates in its structure. Enzymes are non-specific. TRUE FALSE

What happens at the active site? + ↔ In the same way that a key fits into a lock, so a substrate is thought to fit into an enzyme’s active site. The enzyme is the lock, and the reactant is the key. enzyme enzyme ↔ enzyme-reactant complex ↔ + + reactant products

Factors affecting enzymes substrate concentration surface area temperature pressure Can they explain to me why these factors affect enzymes? pH enzyme concentration

Different enzymes have different optimum temperatures and pH values. All enzymes work best at only one particular temperature and pH: this is called the optimum. Different enzymes have different optimum temperatures and pH values.

Effect of temperature on enzyme action The chemical reactions which take place in living cells happen at relatively low temperatures. Like most other chemical reactions, the rate of enzyme controlled reactions increases with an increase in temperature. The enzyme and substrate particles move faster as the temperature increases, so this makes them more likely to collide with enough energy to react. However, this is only true up to temperatures of about 40 degrees celsius. After this the protein structure of the enzyme is affected by the temperature. The long amino acid chain begins to unravel. As a result the shape of the active site changes (show this with the beads – ask Joss). We say that the enzyme has been denatured. It can no longer act as a catalyst, so the rate of the reaction drops dramatically. Most human enzymes work best at 37. Why do you think this is? Not all enzymes work best at around 40 degrees c. Bacteria living in hot springs work at temps over 80 and higher. On the other hand some bacteria which live in very cold deep sea have enzymes working effectively at 0 degrees and below.

Enzymes are not killed!!!!!!!!! Enzymes are molecules not living things. They do NOT die, they become DENATURED. denatured normal heat pH If the temperature and pH changes sufficiently beyond an enzyme’s optimum, the shape of the enzyme irreversibly changes. This affects the shape of the active site and means that the enzyme will no longer work.

Effect of pH on enzyme action Enzymes have their effect by binding the reactants to a specifically shaped active site in the protein molecule. Anything which changes the shape of this active site stops the enzyme from working. Temperature is one thing which changes the shape of a protein molecule. The surrounding pH is another. The shape of the enzymes is the result of forces between the different parts of the protein molecule which hold the folded chains in place. A change in pH affects these forces and changes the shape of the molecule. As a result the active site is lost, so the enzyme can no longer act as a catalyst. Different enzymes have different pH levels at which they work their best and a change in the pH can stop them working completely.

Role of Enzymes Vital to all living cells. Enzymes catalyse processes such as respiration, photosynthesis and protein synthesis in all living cells.