Enzyme Controlled Reaction Lab

What is overall maximal substrate concentration for lactase? Explain why the maximum initial reaction rate cannot be reached at low lactose concentrations.

Enzymes are defined as catalysts that speed up chemical reactions but remain the same themselves. The shape of an enzyme enables it to receive one type of molecule and that specific molecule will fit into the enzyme’s shape. Where a substance fits into an enzyme is called the active site and the substance that fits into the active site is called a substrate. Several factors affect enzymes and the rate of their reactions. Temperature, pH, enzyme concentration, substrate concentration, and the presence of any inhibitors or activators can all affect enzymes. Temperature can affect enzymes because if the temperature gets too high, it can cause the enzyme to denature. pH can affect an enzyme by changing the shape of the enzyme or the charge properties of the substrate so that either the substrate cannot bind to the active site or it cannot undergo catalysis. Every enzyme has an ideal pH that it will strive in. Increasing substrate concentration increases the rate of reaction because more substrate molecules will be interacting and colliding with enzyme molecules, so more product will be formed. Inhibitors can affect enzymes and the rate of their reactions by either slowing down or stopping catalysis. The three types of inhibitors include competitive, non-competitive, and substrate inhibition.

All enzymes are structured to react with unique substrates. and each enzyme has an active site where the substrate bonds to the enzyme. The active site of an enzyme is shaped to fit the specific substrate it reacts with.

Enzymes have an active site which has a complimentary base to a specific substrate, when these bind an enzyme-substrate complex is

Enzymes are proteins that act as catalysts for reactions. This simply means that enzymes lower the activation energy required for a reaction to take place, allowing a particular reaction to take place much quicker and easier. Specific enzymes only lower the activation energy for specific reactions, and enzymes are shape-specific. The unique folds of the amino

J. Moldovan & B. Nilson, (2010), Lab 4 – Enzyme Kinetics, UBCO BIOL/BIOC 393, UBC Vista accessed Monday, November 8th, 2010.

Enzymes have things called ‘Active Sites’ this the spot where substrates bind and chemical reaction takes place. Each enzyme has a different shape, this allows the enzyme to receive only one type of

Enzymes are proteins that act as a catalyst in bringing about specific biochemical reactions when met with particular substrates. Substrates will merge into a suitable area of the enzyme called an active site – this becomes the enzyme/substrate complex. Once the substrate is attached to the active site, the substrate will undergo a procedure where the substrate is modified and released as a product. There are different types of this that can occur, where either a chemical bond is broken in a substrate to produce two separate products; as in the ‘Induced-Fit’ model illustrated in figure 1.a. Chemical bonds can also be built between two substrates to produce a single product.

The purpose of this laboratory experiment is to explore the effects of pH has on a reaction rate. The reaction studied was the breakdown of hydrogen peroxide catalyzed by enzyme peroxidase. Peroxidase is a large protein containing heme co factors in its active site. Four trials were ran at pH levels of 3, 5, 7, and 9. I hypothesized that the reaction would run very quickly at a pH 7, since that is the normal condition of cells where peroxidase is found.

When the substrate enters the active site of an enzyme, the conditions of the active site are altered slightly in order to increase the reactivity and cause the creation of more

pH along with temperature and concentration is a limiting factor of enzyme activity. Enzymes, which are proteins, have a distinct pH range in which they work most effectively. Beyond or below this specific pH, enzyme activity begins to diminish and eventually the enzyme is rendered useless. The optimum pH of an enzyme is the pH at which it is most effective and causes the fastest rate of reaction(source). This decrease in enzyme activity beyond the optimum pH is attributed to the change in shape of the active site(explained earlier) of the enzyme. This change in shape can be brought upon when the surrounding pH moves away from the optimum pH, and it can prevent the enzyme from binding with the substrate.

Each enzyme is very specific and can only catalyze a certain reaction. The specific reaction catalyzed by an enzyme depends on the molecular structure and shape of a small area of the enzyme’s surface called the active site. The active site an attract and hold only its specific molecules. The target molecule that the enzyme attracts and acts upon is called the substrate. The substrate and the active site of the molecule must fit together very closely. Sometimes the enzyme changes its shape slightly to bring about the necessary fit.

Enzymes are natural catalysts that work from the ability to increase the rate of reaction by decreasing the activation energy of a reaction. (Blanco, Blanco 2017) An enzyme can do this 10^8- to 10^10 fold, sometimes even 10^15 fold. (Malacinsk, Freifelder 1998) The substrate will momentarily bind with the enzyme making the enzyme-substrate complex, of which the shape of the substrate is complimentary to the shape of the active site on the enzyme it is binding with. There are two main theories as to how an enzymes and substrates interact, the lock-and-key model and induced fit theory. The lock-and-key model suggests that the enzyme has a specific shape that fits the substrate and only that substrate. The induced fit theory says the active site and substrate are able to change shape or distort for the reaction to take place with (Cooper,

Although there is also a maximum rate, it is not that the substrate will stop producing, it is that the enzyme will be completely saturated thus stopping the production of the reaction. The reaction is also the same with the enzyme concentration in that the production will increase as the saturation increases, but the substrate will also become saturated and will yield production. Enzymes are important in the biological world because it can help a scientist control the reaction of a substance based on the factors he or she wants to follow. This experiment will prove that temperature, pH, substrate concentration, and enzyme concentration can alter the reaction rate of a substance.

Enzymes are proteins that act as catalysts and help reactions take place. In short, enzymes reduce the energy needed for a reaction to take place, permitting a reaction to take place more easily. Some enzymes are shape specific and reduce the energy for certain reactions. Enzymes have unique folds of the amino acid chain which result in specifically shaped active sites (Frankova Fry 2013). When substrates fit in the active site of an enzyme, then it is able to catalyze the reaction. Enzyme activity is affected by the concentrations of the enzymes and substrate present (Worthington 2010). As the incidence of enzyme increases, the rate of reaction increases. Additionally, as the incidence of substrate increases so does the rate of reaction.