Enzimas: Estructura, Características y Funciones

Enzymes: Key Concepts and Functions

Introduction to Enzymes

• Enzymes are globular proteins produced by various organisms, including animal cells, plant cells, fungi, protozoa, and bacteria.

• Their primary function is to accelerate metabolic reactions by lowering the activation energy required for these reactions.

Specificity of Enzymes

• Each enzyme acts on a specific molecule known as the substrate, which is transformed into a product during the reaction without altering the enzyme itself.

• The rate of reaction is defined as the change in quantity of product formed over time; enzymes increase this rate by reducing activation energy.

Mechanism of Action

• For a substrate to convert into a product, it must first bind to the enzyme at a specific region called the active site.

• Enzymes consist of two parts: the apoenzyme (the protein part that is inactive alone) and cofactors (non-protein molecules that assist in enzymatic activity).

Types of Cofactors

• Cofactors can be organic or inorganic molecules that bind tightly or loosely to enzymes.

• The complete active enzyme formed from an apoenzyme and its cofactor is referred to as holoenzyme.

Energy Dynamics in Reactions

• Enzymes lower the activation energy needed for substrates to become products, allowing reactions to occur more quickly with less energy input.

• The process involves forming an enzyme-substrate complex followed by an enzyme-product complex before releasing the final product while remaining unchanged.

Factors Affecting Enzyme Activity

Temperature Influence

• Various factors can affect enzymatic activity; temperature increases molecular motion leading to higher reaction rates up until an optimal point.

• Human enzymes typically have an optimal working temperature around 37–37.5 degrees Celsius; beyond this range (40–42 degrees), enzymes may denature due to disrupted hydrogen bonds.

pH Levels Impact

• Changes in pH can disrupt binding between substrate and enzyme by breaking essential bonds within the enzyme structure.

Enzyme Activity and Inhibition Mechanisms

Optimal pH Levels for Enzymes

• The optimal pH for enzyme activity varies by type; intracellular enzymes typically function best around pH 7, while digestive enzymes thrive in acidic conditions (pH 1-6).

• Alkaline conditions (pH 8-12) are ideal for oral enzymes like amylase, which acts on starch.

Factors Affecting Reaction Velocity

• The reaction speed catalyzed by an enzyme is directly proportional to its concentration; increasing enzyme concentration enhances reaction velocity.

• Similarly, substrate concentration affects reaction speed up to a saturation point where further increases do not significantly change the rate due to active site occupancy.

Enzyme Inhibition Types

Competitive Inhibition

• Certain substances can inhibit enzymatic activity by blocking or distorting the active site, known as inhibitors.

• Competitive inhibition occurs when an inhibitor resembles the substrate and competes for the active site, preventing substrate binding.

Non-Competitive Inhibition

• Non-competitive inhibitors bind to sites other than the active site, causing distortion that impedes substrate binding without competing directly.