Enzymatic Biochemistry Flashcards
Define activation energy:
The energy required for a reaction to start.
What’s an enzyme?
Proteins that lower the energy of activation so that chemical reactions can get started more easily and proceed in conditions that are ‘cell friendly.’ Enzymes along a metabolic pathway can also divide one high-energy chemical reaction into many steps, each requiring only a fraction of the energy needed for the whole process. Finally, enzymes can accelerate the rate of a reaction millions of times over, which is critical to cells that often need large quantities of a particular product within just a few seconds’ time. There are hundreds of kinds of enzymes in a cell body.
What two factors characterize the enzymatic effect on a reaction?
The lowering of the activation energy, and a faster rate of reaction.
However, a reaction with enzymes will release, from the beginning of the reaction to its end, the same amount of energy as without enzymes.
What’s a substrate?
The substance or molecule on which an enzyme functions (e.g.: lactase’s substrate is lactose).
Each enzyme is specific to its substrate.
Enzyme + substrate = enzyme-substrate complex
What’s the active site in an enzyme?
The area where the substrate binds and the chemical reaction takes place (amino acids of the enzyme protein will bind to the substrate).
The active site of an enzyme is shaped to fit it’s enzyme’s substrate perfectly, although an induced fit (shape change) is sometimes necessary.
What are the three factors that affect enzymes?
Substrate concentration, temperature, and pH.
Describe point of saturation, as it relates to substrate concentration:
Point of saturation is when more substrate will not increase the rate of a reaction, because every available enzyme is already working on a substrate.
What are our body’s enzymes’ optimum temperature and optimum pH?
Our body temperature! As for pH, this depends on the enzyme’s location in the body. Different kinds of enzymes may have different optima.
Warmth increases the rate of molecules’ interactions, while cold tends to slow down life processes.
Explain denaturation, as it relates to enzymes:
An enzyme may become denatured, as a result of too high temperature or pH.
A structural change may happen that inhibits the enzyme’s function. If the active site is affected, the enzyme may no longer recognize its substrate.
Define cofactors:
Organic (coenzymes) and inorganic (metal ions) molecules that increase the rate of a reaction or that are required for some enzyme functions (e.g.: prospective groups and coenzymes).
The same cofactors can bind multiple different types of enzymes and may bind some enzymes loosely, as a coenzyme, and others tightly, as a prosthetic group.
Define coenzyme:
Cofactors; Organic molecules that bind loosely to enzymes and help them function (e.g.: vitamins).
They aid in recognizing, attracting, or repulsing a substrate or product, and shuttle chemical groups from one enzyme to another.
Define prosthetic groups:
Cofactors; Organic molecules or metal ions that bind tightly to enzymes. They can also bind to non-enzyme proteins.
They are attached to proteins by covalent bonds.
Holo enzyme
An enzyme that has a helper group; an enzyme with any metal ions or coenzymes attached to it that is ready to catalyze a reaction.
Enzyme regulation
Enzymes are regulated, positive or negatively, to make sure they are working when they need to.
An enzyme activator is a molecule that positively regulates an enzyme’s activity. An enzyme inhibitor is a molecule that binds to an enzyme and disrupts its activity.
These regulators are NOT substrates; they can be proteins or other molecules.
Dehydrogenase
Enzyme that converts alcohol into other chemicals.
