Enzyme Specificity and Function

Enzymes are biological catalysts, meaning they speed up chemical reactions without being consumed in the process.

Enzymes are proteins produced by living cells. They are essential for various biochemical processes in all living organisms.

Enzymes are highly specific, meaning each enzyme typically catalyzes only one or a small number of reactions. This specificity is due to the shape and chemical properties of the enzyme's active site.

The active site is a region on the enzyme molecule where the substrate binds, forming an enzyme-substrate complex. This complex is crucial for catalysis.

A holoenzyme is a fully functional enzyme composed of two parts: a protein component called the apoenzyme and a non-protein component called a cofactor.

A cofactor is a non-protein molecule that is essential for the activity of an enzyme. Cofactors can be either organic or inorganic.

A coenzyme is an organic cofactor. They are often derived from vitamins and play crucial roles in enzymatic reactions.

A prosthetic group is a non-protein cofactor that is tightly bound to the enzyme. It's essential for the enzyme's structure and function.

The minimum energy required for reactants to reach the transition state and form products.

Enzymes lower the activation energy required for a reaction to occur, thereby speeding up the rate of the reaction.

A specific molecule that an enzyme acts upon.

The enzyme acts only on one specific substrate and never acts on any other compound.

The enzyme acts on one type of bond in chemically related compounds, but at different rates.

The enzyme acts only on one type of optically active substance.

The enzyme acts on a specific type of bond at a specific site and attached to a specific group.

The active site of an enzyme is a three-dimensional region where the substrate binds.

Catalysts that are not proteins and can be made up of various inorganic molecules like metals, acids, or bases. They are not specific to a particular reaction and can speed up many different reactions.

Biological catalysts composed of proteins that are highly specific to a particular reaction, meaning they only speed up one or a few specific chemical reactions.

Inorganic catalysts are unaffected by temperature changes (within a reasonable range). They can function effectively across a wide range of temperatures.

Enzymes are sensitive to temperature changes. They function optimally within a specific temperature range and become inactive at extreme temperatures.

Inorganic catalysts can accelerate a wide range of reactions. They don't show preference for one reaction over another.

Enzymes are highly specific to the reactions they catalyze. Each enzyme is designed to interact with a specific substrate.

Inorganic catalysts do not require any specific activator to function. They are ready to work on their own.

Some enzymes require the presence of an activator, which is often a non-protein molecule that helps the enzyme function efficiently.

An enzyme acting on the carboxyl end of a peptide chain, breaking the bond between the terminal amino acid and the rest of the peptide.

An enzyme acting on the amino end of a peptide chain, breaking the bond between the terminal amino acid and the rest of the peptide.

The ability of an enzyme to catalyze a reaction involving two different substrates, producing two distinct products in a single reaction step.

An enzyme capable of acting on a single substrate, producing a single product through two different reactions.

The rate of an enzyme-catalyzed reaction is directly proportional to the concentration of the substrate, until all active sites are saturated with the substrate.

The rate of an enzyme-catalyzed reaction is directly proportional to the concentration of the enzyme, until all substrate molecules are consumed.

The concentration of substrate at which an enzyme reaches half of its maximum velocity (Vmax). A lower Km indicates a higher affinity of the enzyme for the substrate.

Factors influencing the rate of an enzyme-catalyzed reaction, including substrate concentration, enzyme concentration, product concentration, temperature, pH, time, activators, and inhibitors.

The accumulation of reaction products usually decreases enzymatic velocity. Products bind to the active site of an enzyme, forming a complex that inhibits activity. During digestion, absorption removes end products, allowing continued enzyme activity.

Enzymes work best at a specific temperature, called the optimum temperature. Above the optimum, the enzyme can denature and lose its function. Below the optimum, the reaction rate slows down.

Each enzyme has an optimal pH range where it functions best. Extreme pH values can denature the enzyme by altering its shape and active site.

Enzymatic reaction rate decreases over time due to factors like slight enzyme denaturation, accumulation of end products, and depletion of substrate.

Activators are substances that increase enzyme activity. They can act by removing inhibitory peptides, providing reducing agents for enzymes containing -SH groups, or acting as metal ions that bind to the enzyme.

Metal ions can be loosely bound to enzymes (metal ion activated enzymes) or tightly bound (metalloenzymes). These metals play roles in substrate orientation, redox reactions, and electrostatic stabilization.

Inhibitors are substances that reduce enzyme activity. Competitive inhibitors bind to the active site, preventing the substrate from binding. Non-competitive inhibitors bind to a different site on the enzyme, changing its shape and function.

Competitive inhibitors bind to the active site of an enzyme, competing with the substrate for binding. The effect can be overcome by increasing substrate concentration.

A type of enzyme inhibition where the inhibitor permanently binds to the enzyme's active site, rendering it inactive. This binding is often irreversible, meaning the enzyme cannot regain its activity.

Substances produced by living organisms that specifically inhibit the activity of certain enzymes. Their names are usually based on their enzyme targets, like antipepsin for pepsin.

A type of irreversible inhibition where the inhibitor becomes part of the enzyme, modifying its active site and permanently inactivating it. The process often involves a reaction between the inhibitor and the enzyme's active site.

A specific type of enzyme that catalyzes oxidation-reduction reactions. They transfer electrons between molecules, often using oxygen as an electron acceptor.

A type of oxidoreductase that uses only oxygen as an electron acceptor and forms water or hydrogen peroxide as a byproduct. They're further divided based on the specific product formed (water or hydrogen peroxide).

A specific type of oxidase that uses oxygen to remove hydrogen atoms from their substrate. This process, often called aerobic respiration, plays a critical role in energy production.

A specific type of oxidase that catalyzes the oxidation of tyrosine (an amino acid). This reaction is important in the production of melanin, the pigment responsible for skin and hair color.

A specific type of oxidase that uses molecular oxygen to produce hydrogen peroxide. They are involved in various metabolic pathways, such as purine metabolism.