Enzymes are biological molecules (typically proteins) that significantly speed up the rate of virtually all of the chemical reactions that take place within cells.They are vital for life and serve a wide range of important functions in the body, such as aiding in digestion and metabolism. Some enzymes help break large molecules into smaller pieces that are more easily absorbed by the body. Other enzymes help bind two molecules together to produce a new molecule. Enzymes are highly selective catalysts, meaning that each enzyme only speeds up a specific reaction Describe the structure of an enzyme
The structure of an enzyme is crucially important for its function. The reaction that an enzyme catalyses occurs on the active site, which is the area of the protein in which the substrate can bind and the chemical reaction can take place. The active site is usually on the surface of the protein so it can be easily accessed, and usually has a highly specific structure that allows it to bind its substrate and carry out its catalytic activity. This structure is determined by the different side chains and modifications present in amino acids in the chain, and the resulting final structure the enzyme adopts. Usually, each enzyme only has one active site that can bind one substrate or class of substrates. Explain that enzymes have an active site to which specific substrates bind.
An enzyme is a globular protein which acts as a biological catalyst by speeding up the rate of a chemical reaction. Enzymes are not changed or consumed by the reactions they catalyse and thus can be reused. Enzymes are typically named after the molecules they react with (called the substrate) and end with the suffix ‘-ase’. The active site is the region on the surface of the enzyme which binds to the substrate molecule. The active site and the substrate complement each other in terms of both shape and chemical properties. Only a specific substrate is capable of binding to a particular enzyme’s active site
Outline the three stages of enzyme activity.
Enzyme reactions typically occur in aqueous solutions. Consequently, the substrate and enzyme are usually moving randomly within the solution. This is referred to as Brownian motion. Sometimes an enzyme may be fixed in position (e.g. membrane-bound) – this serves to localize reactions to particular sites Four Steps of Enzyme Action
image from BBC Bitesize Explain how temperature, pH and substrate concentration affect the rate of activity of enzymes.
The activity of an Enzyme is affected by its environmental conditions. Changing these alter the rate of reaction caused by the enzyme. In nature, organisms adjust the conditions of their enzymes to produce an Optimum rate of reaction, where necessary, or they may have enzymes which are adapted to function well in extreme conditions where they live. Temperature
pH - Acidity and Basicity pH measures the Acidity and Basicity of a solution. It is a measure of the Hydrogen Ion (H+) concentration, and therefore a good indicator of the Hydroxide Ion (OH-) concentration. It ranges from pH1 to pH14. Lower pH values mean higher H+ concentrations and lower OH- concentrations.
Concentration
Substrate Concentration Increasing Substrate Concentration increases the rate of reaction. This is because more substrate molecules will be colliding with enzyme molecules, so more product will be formed.
Enzyme Concentration
State the effect of denaturation on enzyme structure and function.
The important part of an enzyme is called the active site. This is where specific molecules bind to the enzyme and the reaction occurs.Anything that changes the shape of the active site stops the enzyme from working. This is similar to a key that opens a door lock. It does not matter what a key handle looks like, but if you change the shape of the ‘teeth’ the key no longer works.The shape of the active site is affected by pH. This is why enzymes will only work at a specific pH, as well as a specific temperature. Change the pH and the enzyme stops working. Increasing the temperature to 60°C will cause a permanent change to the shape of the active site. This is why enzymes stop working when they are heated. We say they have become denatured.
Explain how immobilized enzymes are widely used in industry.
Enzyme immobilization is the process of confining the enzyme molecule to a distinct phase from the one where in the substrates and the products are present. This allows the enzyme to retain its catalytic activity and be repeatedly and continuously used. Applications of enzyme immobilization
image from RSC Publishing - Royal Society of Chemistry Outline four reasons for using lactase in food processing.
Lactose is the sugar found in milk. It can be broken down by the enzyme lactase into glucose and galactose. However some people lack this enzyme and so cannot break down lactose leading to lactose intolerance. Lactose intolerant people need to drink milk that has been lactose reduced. Lactose-free milk can be made in two ways. The first involves adding the enzyme lactase to the milk so that the milk contains the enzyme. The second way involves immobilizing the enzyme on a surface or in beads of a porous material. The milk is then allowed to flow past the beads or surface with the immobilized lactase. This method avoids having lactase in the milk.
image fromBourgeois Essence Identify the different types of enzymes, their substrates and products
image from BioNinja Outline the two models used to describe the way enzymes interact with substrates.
The two models to explain the actions of enzymes with substrates are the Lock and Key model & Induced fit model.In lock and key the enzyme is the lock and the substrate is the key. As with a lock and the key that opens it the shapes must be complementary and this shape can not change. Induced fit looks at the active site of enzymes as being slightly more flexible and initially uncomplementary. It suggests that it is the binding of the substrate to enzyme that causes the active site to change into a complementary shape and allow the enzyme-substrate complex to form.
https://alevelbiology.co.uk/notes/biological-catalysts-enzymes/ Distinguish between competitive and noncompetitive inhibitors.
An enzyme inhibitor is a molecule that disrupts the normal reaction pathway between an enzyme and a substrate. Enzyme inhibitors can be either competitive or non-competitive depending on their mechanism of action
Key Term:
Correct use of terminology is a key skill in Biology. It is essential to use key terms correctly when communicating your understanding, particularly in assessments. Use the quizlet flashcards or other tools such as learn, scatter, space race, speller and test to help you master the vocabulary Paul Andersen explains how enzymes are used to break down substrates. The correct shape of the active site allows a key/lock fit between the enzyme and the substrate. The enzyme catalase is used to break down hydrogen peroxide. The importance of cofactors and coenzymes is emphasized. Competitive and allosteric inhibition is also included. The Amoeba Sisters explain enzymes and how they interact with their substrates Enzymes are really important proteins, that speed up the rates of reactions such as in photosynthesis, respiration and protein synthesis. What are enzymes? Why they're nature's little factory workers. They chop up certain things! They build up others! Pretty amazing the kind of chemistry nature can do given enormous polypeptide chains with unfathomable variability and billions of years of evolution, no? Factors that Affect Enzymes Dr. Kiki breaks down the breakdown of proteins. All adult mammals but humans are lactose intolerant. Follow human geneticist Spencer Wells, director of the Genographic Project of the National Geographic Society, as he tracks down the genetic and societal changes associated with the ability to digest lactose as adults—or lactose tolerance Allosteric Regulation of Enzymes |