Name: how enzymes change shape to catalyze
Uploaded: 2023-04-30T10:09:56.000Z
Duration: 1 min 13 s
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K12 Standards

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North Carolina K-12 Science Standard Course of Study

9-12

Biology

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From Molecules to Organisms- Structures and Processes

LS.Bio.1.2

introduction-to-mechanisms-of-enzyme-catalysis

Introduction to Mechanisms of Enzyme Catalysis

Enzymes catalyze reactions using various physical and chemical mechanisms to lower the activation energy.
These mechanisms may increase the reaction rate by positioning the enzyme and substrate appropriately, stabilizing the transition state, and helping to form or break bonds.
Most enzymes adopt an induced fit when they bind their substrates. This conformational change alters the relative positions at the amino acids to increase interactions with the substrate.
In reactions with multiple substrates, enzymes often position the molecules to resemble the transition state to aid their transformation.
Many enzymes require metal ions for catalysis. Metal ions attract oppositely charged groups on substrates and orient them for the reaction. Ions can also change their oxidation state to stabilize charges on reaction intermediates.
In some enzymes, amino acids accept or donate protons to locally change the pH or react directly with the substrate. This can strengthen or weaken bonds to increase reaction rates.

introduction to mechanisms of enzyme catalysis

For many years, scientists thought that enzyme-substrate binding took place in a simple &#34;lock-and-key&#34; fashion. This model stated that the enzyme and substrate fit together perfectly in one instantaneous step. However, current research supports a more refined view scientists call induced fit. The induced-fit model expands upon the lock-and-key model by describing a more dynamic interaction between enzyme and substrate. As the enzyme and substrate come together, their interaction causes a mild shift in the enzyme&#39;s structure that confirms an ideal binding arrangement between the enzyme and the substrate&#39;s transition state. This ideal binding maximizes the enzyme&#39;s ability to catalyze its reaction.
The active sites of enzymes are suited to provide specific environmental conditions and are also subject to local environmental influences. Increasing the environmental temperature generally increases reaction rates, enzyme-catalyzed or otherwise. However, increasing or decreasing the temperature outside of an optimal range can affect chemical bonds within the active site to influence substrate binding. High temperatures will eventually cause enzymes, like other biological molecules, to denature, changing the substance&#39;s natural properties. Likewise, the local environment&#39;s pH can also affect enzyme function. Active site amino acid residues have their own acidic or basic properties optimal for catalysis. Enzymes function optimally within a specific pH range, and altering the temperature or acidic or basic nature can affect the catalytic activity.
Many enzymes don&#39;t work optimally, or even at all, unless bound to other specific non-protein helper molecules, either temporarily through ionic or hydrogen bonds or permanently through stronger covalent bonds. Two types of helper molecules are cofactors and coenzymes. Binding to these molecules promotes optimal conformation and function for their respective enzymes. Cofactors are inorganic ions such as iron (Fe2+) and magnesium (Mg2+). For example, DNA polymerase requires a bound zinc ion (Zn2+) to function. Coenzymes are organic helper molecules with a basic atomic structure comprised of carbon and hydrogen, required for enzyme action. The most common sources of coenzymes are dietary vitamins. Some vitamins are precursors to coenzymes, and others act directly as coenzymes.
This text is adapted from Openstax, Biology 2e, <a href="https://openstax.org/books/biology-2e/pages/6-5-enzymes?query=Enzyme%20Kineticsp-courses/pages/6-5-enzymes">Section 6.5 Enzymes</a>

For many years, scientists thought that enzyme-substrate binding took place in a simple &#34;lock-and-key&#34; fashion. This model stated that the enzyme ...

Education

JoVE Core

Cell Biology

Unit 1

Energy and Catalysis

KEY TERMS AND CONCEPTS

how enzymes change shape to catalyze

Enzyme catalysis depends on how enzymes bind substrates and how the active site responds during the reaction. Scientists once described this process with a simple lock-and-key model, where the enzyme and substrate fit together in one instant. Research now supports induced fit, a more dynamic model in which binding causes a small change in the enzyme’s shape. That shift helps create an ideal match between the enzyme and the substrate’s transition state, which improves catalysis.

The active site also depends on its local environment. Temperature can raise reaction rates in general, including enzyme-catalyzed reactions, when it stays near the enzyme’s optimal range. If temperature moves too far outside that range, it can disrupt chemical bonds in the active site and change substrate binding. At very high temperatures, enzymes can denature, which means they lose their natural structure and properties.

pH can also affect enzyme function. Amino acid residues in the active site have their own acidic or basic properties, and these properties work best within a specific pH range. Changing the pH can reduce catalytic activity. Many enzymes also need helper molecules to work properly. These helpers may bind temporarily through ionic or hydrogen bonds, or permanently through stronger covalent bonds.

Two major helper molecules are cofactors and coenzymes. Cofactors are inorganic ions, such as iron and magnesium. One example is the zinc ion required by DNA polymerase. Coenzymes are organic helper molecules made mostly of carbon and hydrogen. Many coenzymes come from dietary vitamins, and some vitamins are direct coenzymes while others serve as precursors to them.

How Enzymes Change Shape to Catalyze

the first law of thermodynamics

Energy Changes in Cells and Matter

The first law of thermodynamics describes how energy changes form in the universe. The total amount of energy stays constant. Energy can move from one place to another or change into a different form, but it cannot be created or destroyed. These energy changes happen in everyday life. A light bulb changes electrical energy into light energy. A gas stove changes chemical energy in natural gas into heat energy. Plants also carry out a major energy transformation when they convert sunlight energy...

the second law of thermodynamics

Entropy and Spontaneous Change

Entropy helps predict whether a process will happen on its own. Entropy is a measure of randomness or disorder in a system. High entropy means high disorder and low energy. A student’s bedroom is a simple example. If no work is done, the room becomes messy over time. That messy state is highly disordered and has high entropy. To make the room clean again, energy must be added as the student puts things away. That organized state has low entropy. Processes that increase the entropy of the...

enthalpy within the cell

Cellular Enthalpy and Energy Changes

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Gibbs Free Energy and Reaction Work

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endergonic and exergonic reactions in the cell

endergonic-and-exergonic-reactions-in-the-cell

Cell Reactions That Release or Store Energy

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the equilibrium binding constant and binding strength

the-equilibrium-binding-constant-and-binding-strength

How Equilibrium Binding Constant Affects Binding

The equilibrium binding constant describes how strongly two molecules bind at equilibrium. It is a useful way to compare binding strength in molecular interactions. This topic focuses on how binding is measured and what the equilibrium binding constant means. A higher value indicates stronger binding, while a lower value indicates weaker binding. Understanding this constant helps explain how tightly molecules stay together under equilibrium conditions. The page also connects the binding...

free energy and equilibrium

Free Energy and Reaction Direction

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non-equilibrium in the cell

Cells Stay Out of Equilibrium

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enzymes and activation energy

How Enzymes Lower Reaction Energy

Enzymes lower the energy needed for a chemical reaction to begin. That starting energy is called activation energy, or free energy of activation, and it is often written as Ea. During a reaction, bonds break and new bonds form. In glucose breakdown, for example, bonds between carbon atoms break and release energy because they are energy-storing bonds. Before a reaction can move forward, reactant molecules must reach a high-energy, unstable shape called the transition state. To get there, the...

introduction to enzyme kinetics

Graphing Enzyme Kinetics Data

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turnover number and catalytic efficiency

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catalytically perfect enzymes

Diffusion-Controlled Enzymes and Reaction Speed

Catalytically perfect enzymes are enzymes that speed up biochemical reactions at very high rates. The idea was first proposed by W. J. Albery and J. R. Knowles in 1976. These enzymes have catalytic efficiency values of about 10^8 to 10^9 M^-1 s^-1 and are also called diffusion-controlled enzymes because diffusion of the substrate into the active site is the only rate-limiting step. Examples of catalytically perfect enzymes include triose phosphate isomerase, fumarase, and superoxide dismutase.

Enzyme catalysis depends on how enzymes bind substrates and how the active site responds during the reaction. Scientists once described this process with a simple lock-and-key model, where the enzyme and substrate fit together in one instant. Research now supports induced fit, a more dynamic model in which binding causes a small change in the enzyme’s shape. That shift helps create an ideal match between the enzyme and the substrate’s transition state, which improves catalysis. The active site...

ligand binding and linkage

Ligand Binding and Allosteric Effects

Ligand binding and linkage describe how one molecule can affect another when it binds to a protein. In this topic, the focus is on how binding at one site can influence activity at a different site on the same protein. This idea is important for understanding protein function in high school biology. It helps explain why some proteins respond more strongly after a ligand attaches. The transcript centers on the connection between ligand binding and linkage, which is a key concept in molecular...

cooperative allosteric transitions

How Proteins Shift Shape Together

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ribozymes

Catalytic RNA: Ribozymes in Action

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atp energy storage and release

ATP Powers Cellular Transport and Reactions

ATP powers cellular transport and many reactions by transferring energy through phosphorylation. ATP is a highly unstable molecule. If it is not used quickly, it breaks down into ADP and inorganic phosphate, and the released energy is lost as heat. Cells use ATP through energy coupling. This means the exergonic reaction of ATP hydrolysis is linked to an endergonic reaction so the reaction can move forward. One major example is the sodium-potassium pump, a transmembrane ion pump that is vital...

atp and macromolecule synthesis

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coupled reactions

ATP Powers Cellular Work

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key terms and concepts

Explore induced fit, active site shape, temperature and pH effects, plus cofactors and coenzymes that help enzymes work in high school biology.

How Enzymes Change Shape to Catalyze | JoVE K12

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JoVE Core Cell Biology illustrates complex cellular processes in easy-to-understand yet comprehensive animated video lessons. This collection focuses on the essential components and functions of cells, including organelles and membranes, cellular transport, and cell energetics. It is complemented by scientist-in-action videos that demonstrate the application of cell biology in real-world research experiments.

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HIgh School

BIO.2

BIO.2.c

Chemistry

CH.7

CH.7.f

Florida Department of Education

High School

Life Science

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SC.912.L.18.4

SC.912.L.18.11

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BIO.11

BIO.11.B

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Nucleic Acid Structure

The pentose sugar in DNA is deoxyribose, while in RNA the pentose sugar is ribose. The difference between the sugars is the presence of the hydroxyl group ...

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Construct an explanation to illustrate relationships between structure and function of major macromolecules essential for life.

LS.Bio.1.1

Introduction to Enzymes

The use of enzymes by humans dates to 7000 BCE. Humans first used enzymes to ferment sugars and produce alcohol without knowing that this was an ...

Enzymes and Activation Energy

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Ligand Binding and Linkage

Cooperative Allosteric Transitions

Ribozymes

Carry out investigations to illustrate how enzymes act as catalysts for biochemical reactions and how environmental factors affect enzyme activity.

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Cells are the smallest and basic units of life, whether it is a single cell that forms the entire organism, e.g., in a bacterium or trillions of them, ...

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Prokaryotic Cells

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Cytoplasm

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The Nucleus

The nucleus is a membrane-bound organelle that acts as a control center in a eukaryotic cell. It contains chromosomal DNA, which controls gene expression ...

Endoplasmic Reticulum

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Ribosomes

Ribosomes translate genetic information encoded by messenger RNA (mRNA) into proteins. Both prokaryotic and eukaryotic cells have ribosomes. Cells that ...

Golgi Apparatus

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Lysosomes

Lysosomes are membrane-enclosed spherical sacs derived from the Golgi apparatus. The most important function of the lysosome is degrading macromolecules ...

Peroxisomes

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LS.Bio.1.3

Analyze how the relationship between structure and function supports life processes within organisms.

How Enzymes Change Shape to Catalyze

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