Biochemistry: Enzymes

Is anyone Lactose intolerant? What is that?

Enzymes A specialized type of protein Function in our body: acts like a catalyst = substance that speeds up the rate of a chemical reaction but it is not used up in the reaction.

Enzymes Enzyme(s) reduce the activation energy = amount of energy needed to begin a reaction Usually end is “–ase”. Coenzymes = an organic molecule associated with the enzyme to help in the reaction.

Progress of the reaction Free energy of activation Enzymes Free Energy Progress of the reaction Reactants Products Free energy of activation

Enzymes Need an active site on the enzyme Active site = attracts and hold only specific molecules called substrates. “Lock and key” system- one “key” will fit “lock”; perfect fit Induced Fit – “lock” will mold around the “Key” if fit is close enough

Enzymes Therefore, enzymes enable molecules called substrates to undergo a chemical change to form new substances called products.

Enzymes Active Site

Example of the hydrolysis of sucrose using the enzyme (sucrase)

Enzyme Inhibitors Competitive Inhibitors = a substances that reduces the activity of an enzyme by entering the active site in place of the substrate whose structure is very similar.

Enzyme Inhibitors Noncompetitive inhibitors: Inhibitors that do not enter the active site, but bind to another part of the enzyme causing the enzyme to change its shape, which in turn alters the active site.

Enzymes Could not survive without enzymes! (almost all chemical reactions in cells require an enzyme) Speeds up reactions in: Digestion of food Synthesis of molecules Storage and release of energy

Enzymes Enzymes are named for the compounds they work on. You drop the current compound ending and replace it with –ase.

Enzymes For example: Lactose’s enzyme is lactase Maltose’s enzyme is maltase Sucrose’s enzyme is sucrase Amylase (in your saliva) is the enzyme for starch (amylose)

Enzymes 2 Factors that Affect Enzymes: Temperature – Too high temperatures will denature (change the shape of) the active site of the enzyme, causing the enzyme to not work properly. pH – every enzyme has an optimum pH in which they will work. Altering the pH will cause the enzyme to not work properly.

Examples Cat box example pH (most like 6 - 8 pH near neutral) Urea + urease  ammonia + carbon dioxide Clean litter in cooler temps = less smell due to slower rate of reaction pH (most like 6 - 8 pH near neutral) Lemon Juice on apple Polyphenol oxidase (PPO) is the enzyme that reacts with oxygen to turn the apple brown

How Does our Body get Energy from the Breaking Down of Molecules? Energy is released when a chemical bond is broken.

Enzymes Analysis of Enzyme actions Draw a conclusion based on each graph below!

Dehydration synthesis or hydrolysis?