Enzymes & Regulation 6th Grade PDF

6th Grade Enzymes and Regulation MC 101- LP- Midterms  LEARNING OBJECTIVES: Define enzymes. Identify the different classes of enzymes. Explain the factors that influence enzyme activity. Explain the mechanism of enzyme action and regulation. Discuss the use of enzymes in...

6th Grade Enzymes and Regulation MC 101- LP- Midterms  LEARNING OBJECTIVES: Define enzymes. Identify the different classes of enzymes. Explain the factors that influence enzyme activity. Explain the mechanism of enzyme action and regulation. Discuss the use of enzymes in medicine. Introduction The cells of your body are capable of making many different enzymes, and at first you might think: great, let’s crank all of those enzymes up and metabolize as fast as possible! As it turns out, though, you really don’t want to produce and activate all of those enzymes at the same time, or in the same cell. Needs and conditions vary from cell to cell and change in individual cells over time. For instance, stomach cells need different enzymes than fat storage cells, skin cells, blood cells, or nerve cells. Also, a digestive cell works much harder to process and break down nutrients during the time that follows a meal as compared with many hours after a meal. As these cellular demands and conditions changes, so do the amounts and functionality of different enzymes. ENZYMES Are protein catalysts that increase the velocity of a chemical reaction and are not consumed during the reaction. “-ase” PROPERTIES - ENZYMES Active site Efficiency Specificity Some enzymes require nonproteins for enzymatic activity Regulation Location within the cell The Six (6) Major classes of enzymes: Oxidoreductases Transferases Hydrolases Lyases Isomerases Ligases Oxidoreductases Cataylze oxidation-reduction reactions Transferases Cataylze transfer of C-, N-, P- containing groups Hydrolases Cataylze cleavage of bonds by addition of water. Lyases Cataylze cleavage of C-C, C-S, certain C-N bonds Isomerases Cataylze rearrangement of optical or geometric isomers Ligases Cataylze formation of bonds between carbon and O, S, and N coupled to hydrolysis of high energy phosphates  Because enzymes guide and regulate the metabolism of a cell, they tend to be carefully controlled. We’ll take a look at factors that can affect or control enzyme activity. These include pH and temperature, as well as: 01 02 Regulatory molecules Cofactors Enzyme activity may be turned Many enzymes are only active "up" or "down" by activator and when bound to non-protein inhibitor molecules that bind helper molecules known as specifically to the enzyme. cofactors. 03 04 Compartmentalization Feedback inhibition Storing enzymes in specific Key metabolic enzymes are often compartments can keep them from inhibited by the end product of the doing damage or provide the right pathway they control (feedback conditions for activity inhibition).  Regulatory molecules Enzymes can be regulated by other molecules that either increase or reduce their activity. Molecules that increase the activity of an enzyme are called activators, while molecules that decrease the activity of an enzyme are called inhibitors. There are many kinds of molecules that block or promote enzyme function, and that affect enzyme function by different routes. Competitive vs. noncompetitive In many well-studied cases, an activator or inhibitor's binding is reversible, meaning that the molecule doesn't permanently attach to the enzyme. Some important types of drugs act as reversible inhibitors. For example, the drug tipranivir, which is used to treat HIV, is a reversible inhibitor. It blocks activity of a viral enzyme that helps the virus make more copies of itself. Reversible inhibitors are divided into groups based on their binding behavior. The two important groups: competitive and noncompetitive inhibitors. - An inhibitor may bind to an enzyme and block binding of the substrate, for example, by attaching to the active site. This is called competitive inhibition, because the inhibitor “competes” with the substrate for the enzyme. That is, only the inhibitor or the substrate can be bound at a given moment. - In noncompetitive inhibition, the inhibitor doesn't block the substrate from binding to the active site. Instead, it attaches at another site and blocks the enzyme from doing its job. This inhibition is said to be "noncompetitive" because the inhibitor and substrate can both be bound at the same time. Competitive and non-competitive inhibitors can be told apart by how they affect an enzyme's activity at different substrate concentrations. - If an inhibitor is competitive, it will decrease reaction rate when there's not much substrate, but can be "out-competed" by lots of substrate. That is, the enzyme can still reach its maximum reaction rate given enough substrate. In that case, almost all the active sites of almost all the enzyme molecules will be occupied by the substrate rather than the inhibitor. - If an inhibitor is noncompetitive, the enzyme-catalyzed reaction will never reach its normal maximum rate even with a lot of substrate. This is because the enzyme molecules with the noncompetitive inhibitor bound are "poisoned" and can't do their job, regardless of how much substrate is available. On a graph of reaction velocity (y-axis) at different substrate concentrations (x-axis), you can tell these two types of inhibitors apart by the shape of the curves: Factors affecting reaction velocity 01 Substrate concentration 02 Temperature 03 pH  Allosteric regulation Allosteric regulation, broadly speaking, is just any form of regulation where the regulatory molecule (an activator or inhibitor) binds to an enzyme someplace other than the active site. The place where the regulator binds is called the allosteric site.  Pretty much all cases of noncompetitive inhibition (along with some unique cases of competitive inhibition) are forms of allosteric regulation. However, some enzymes that are allosterically regulated have a set of unique properties that set them apart. These enzymes, which include some of our key metabolic regulators, are often given the name of allosteric enzymes. Allosteric enzymes typically have multiple active sites located on different protein subunits. When an allosteric inhibitor binds to an enzyme, all active sites on the protein subunits are changed slightly so that they work less well. There are also allosteric activators. Some allosteric activators bind to locations on an enzyme other than the active site, causing an increase in the function of the active site. Also, in a process called cooperativity, the substrate itself can serve as an allosteric activator: when it binds to one active site, the activity of the other active sites goes up. This is considered allosteric regulation because the substrate affects active sites far from its binding site.  Cofactors and Enzymes Many enzymes don’t work optimally, or even at all, unless bound to other non-protein helper molecules called cofactors. These may be attached temporarily to the enzyme through ionic or hydrogen bonds, or permanently through stronger covalent bonds. Common cofactors include inorganic ions such as iron (Fe2+) and magnesium (Mg2+). For example, the enzyme that builds DNA molecules, DNA polymerase, requires magnesium ions to function. Coenzymes are a subset of cofactors that are organic (carbon-based) molecules. The most common sources of coenzymes are dietary vitamins. Some vitamins are precursors to coenzymes and others act directly as coenzymes. For example, vitamin C is a coenzyme for several enzymes that take part in building the protein collagen, a key part of connective tissue.  Enzyme compartmentalization Enzymes are often compartmentalized (stored in a specific part of the cell where they do their job) -- for instance, in a particular organelle. Compartmentalization means that enzymes needed for specific processes can be kept in the places where they act, ensuring they can find their substrates readily, don't damage the cell, and have the right microenvironment to work well. For instance, digestive enzymes of the lysosome work best at a pH around 5.0, which is found in the acidic interior of the lysosome (but not in the cytosol, which has a pH of about 7.2) Lysosomal enzymes have low activity at the pH of the cytosol, which may serve as "insurance" for the cell: even if a lysosome bursts and spills its enzymes, the enzymes will not begin digesting the cell, because they will no longer have the right pH to function.  Feedback Inhibition of Metabolic Pathways In the process of feedback inhibition, the end product of a metabolic pathway acts on the key enzyme regulating entry to that pathway, keeping more of the end product from being produced. This may seem odd – why would a molecule want to turn off its own pathway? But it’s actually a clever way for the cell to make just the right amount of the product. When there’s little of the product, the enzyme will not be inhibited, and the pathway will go full steam ahead to replenish the supply. When there’s lots of the product sitting around, it will block the enzyme, preventing the production of new product until the existing supply has been used up. Typically, feedback inhibition acts at the first committed step of the pathway, meaning the first step that’s effectively irreversible. However, feedback inhibition can sometimes hit multiple points along a pathway as well, particularly if the pathway has lots of branch points. The pathway steps regulated by feedback inhibition are often catalyzed by allosteric enzymes Reference: Moore, T. (2022). Biochemistry For Dummies (3rd Edition). Wiley Publishing, Inc. Ferrier, D. (2018). Lippincott illustrated review: biochemistry (7th edition). Wolters kluwer Thanks! Do you have any questions? CREDITS: This presentation template was created by Slidesgo, including icons by Flaticon, and infographics & images by Freepik