Name: enzyme helpers: metals, vitamins, and more
Uploaded: 2019-07-31T14:21:57.000Z
Duration: 1 min 27 s
Channel: JoVE

- [강사] 많은 경우에 효소는보조인자라고 불리는 추가 분자가 기능을 발휘합니다이 도우미 분자는 다음과 같이금속 이온 또는 유기 비단백질 분자로 분류될 수 있으며예를 들어, 해당 과정의 첫 단계에서보조인자 마그네슘은 ATP에 결합되어두 인산염 그룹 사이의 결합을 강화시킵니다이 작용은 마지막 인산염 그룹이효소 헥소키나아제에 의해 보다 쉽게 방출되게 하며글루코오스를 글루코오스 6-인산으로 전환시킵니다따라서 보조인자로서의 마그네슘은ATP의 효율을 증가시킵니다보조인자의 다른 부분 집합인 보효소는유기 화합물로 보통 비타민의 유도체입니다예를 들어, 비타민 C는 중요한 보효소로서단백질 콜라겐의 합성에 작용합니다콜라겐이 수산화 효소에 결합하면뒤이어 비타민 C가 효소에 결합되고수산기를 기증하게 됩니다이제 가수분해된 수산화 효소의 도움으로콜라겐의 형태가 바뀌는데이는 최종적으로 삼중 나선 구조가 되며유지에 있어 필수적인 요소로중요한 신체 조직에 기여합니다

Tong, Liang. "비오틴 의존성 카르복실라제의 구조 및 기능." Cellular and Molecular Life Sciences 70, no. 5 (2013): 863-891. [<a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3508090/">출처</a>]

Yang, Wei, Jae Young Lee, and Marcin Nowotny. "핵산의 제조 및 파괴: 2-Mg2+-이온 촉매 및 기질 특이성." Molecular Cell 22, no. 1 (2006): 5-13. [<a href="https://doi.org/10.1016/j.molcel.2006.03.013">출처</a>]

보조인자와 보조효소

Cofactors and Coenzymes

효소는 적절한 기능을 위해 보조인자와 보조효소라는 추가 성분이 필요합니다. 보조인자(cofactor)는 금속 이온이고 보조효소(coenzyme)는 단백질이 아닌 유기 분자입니다. 이 두 유형의 도우미 분자는 모두 효소에 단단히 결합하거나 기질(substrate)이 결합할 때만 결합할 수 있습니다.
 
 보조인자는 성숙한 단백질의 약 30%에 존재합니다. 보조인자는 자주 효소 단백질이 접힐 때 통합되어 효소의 촉매 활동에 관여합니다. 마그네슘은 DNA 중합효소(DNA polymerase; DNA 폴리머레이스)를 포함해 인체의 300여 효소에 필수적인 보조인자입니다. DNA 중합효소의 경우 마그네슘 이온은 DNA 뼈대의 인산다이에스터결합(phosphodiester bond; 포스포다이에스터결합) 형성을 돕습니다. 철, 구리, 코발트, 망간도 흔한 보조인자입니다.
 
 여러 비타민은 비단백질 유기 도우미 분자인 보조효소입니다. 예를 들어 비타민 B의 일종인 비오틴(biotin)은 분자에서 분자로 이산화탄소를 전달하는 다양한 효소에서 중요합니다. 비오틴, 비타민 A 등은 인간의 세포에서 만들어질 수 없기 때문에 식단을 통해 섭취되어야 합니다.

효소는 적절한 기능을 위해 추가 성분을 필요로 합니다. 분자에는 보조 인자와 코엔자임의 두 가지 종류가 있습니다. 보조 인자는 금속 이온입니다 ...

Education

교육

JoVE Core

Biology

생물학

Cellular Processes

세포 과정

Metabolism

신진대사

KEY TERMS AND CONCEPTS

주요 용어 및 개념

enzyme helpers: metals, vitamins, and more

Enzyme helpers are needed for many enzymes to work properly. These helpers fall into two groups: cofactors and coenzymes. Cofactors are metallic ions, while coenzymes are non-protein organic molecules. Both can be tightly bound to an enzyme or attach only when the substrate binds.

Cofactors are common in mature proteins, appearing in about 30% of them. They are often added as the enzyme folds and help with catalytic activity. Magnesium is one important cofactor, and it is needed by more than 300 enzymes in the human body, including DNA polymerase. In DNA polymerase, magnesium helps form the phosphodiester bond in the DNA backbone. Iron, copper, cobalt, and manganese are other common cofactors.

Many coenzymes come from vitamins. These organic helper molecules assist enzymes during reactions. Biotin, which is a B vitamin, helps several enzymes move carbon dioxide from one molecule to another. Vitamin A and other vitamins must come from the diet because human cells cannot make them.

Enzyme Helpers: Metals, Vitamins, and More

what is metabolism?

Metabolism, Energy, and Cell Reactions

Metabolism is the set of chemical reactions that happen in a cell. It includes anabolism, which builds molecules, and catabolism, which breaks them down. These reactions help cells manage energy and keep life processes running. Cells use metabolism to turn food into energy, make cell parts, and remove waste products. Food stores potential energy in the bonds between atoms. Catabolic pathways break large food molecules into smaller ones and release that energy. Anabolic pathways use that energy...

first law of thermodynamics

Energy Flow in a Food Web

Energy flow in a food web shows the First Law of Thermodynamics in action. Energy cannot be created or destroyed. It can only change form as it moves through living things and the environment. Sunlight is the starting point. Plants capture radiant energy from the sun during photosynthesis and turn it into chemical energy stored in complex carbohydrates. At the same time, oxygen is released into the atmosphere. Herbivores eat the plants and use those sugars during digestion. The energy is...

second law of thermodynamics

Entropy in Food Web Energy Flow

The Second Law of Thermodynamics explains why entropy increases as energy moves through a system. Entropy means the amount of disorder in a system. Each time energy is transferred or transformed, some energy is lost as unusable heat. That heat can raise the motion of nearby molecules for a short time and make the surroundings less ordered and more random. This idea also appears in a food web. Primary producers, such as plants, take in energy from the sun and make food. During this process,...

kinetic energy

Motion as a Source of Energy

Kinetic energy is the energy of motion. It appears when an object is moving and can do work or cause change. A waterfall is one clear example. Water behind a dam has potential energy, but when it rushes downward, that moving water has kinetic energy. When the water reaches the bottom and stops moving, its energy can become potential energy again. Kinetic energy also shows up in living systems. Plants absorb light particles, called photons, which move very fast and help create chemical energy...

potential energy

Stored Energy in Motion and Bonds

Stored energy in motion and bonds is called potential energy. It depends on the structure of an object or the position of matter in space. Raising a kettlebell changes its location and increases its potential energy. A stretched rubber band also stores potential energy, which can later change into kinetic energy. Chemical bonds between atoms hold another form of stored energy called chemical energy. These bonds involve attractive forces, and that energy can change into other forms during a...

free energy

Gibbs Free Energy in Chemical Reactions

Gibbs free energy is a measure of useful energy that can be taken from a chemical reaction to do work. It is written as G and named for scientist Gibbs, who discovered it. This energy is what remains after entropy is considered. A reaction can either take in energy or release it. Reactions that absorb energy are called endergonic reactions. Reactions that release energy are called exergonic reactions. The direction of energy flow helps show which type of reaction is happening. Plants carry...

activation energy

How Catalysts Lower Reaction Barriers

Activation energy is the minimum energy a chemical reaction needs to keep going. When the activation energy is higher, the reaction usually happens more slowly. Adding heat can speed the reaction because molecules move faster and collide more often. As reactants collide, bonds break and the reaction moves through an uphill phase. That step creates the transition state, which is an unstable, high-energy state of the reactants. After that, new bonds form, products appear, and free energy is...

hydrolysis of atp

ATP Breakdown and Energy Release

ATP breakdown releases energy for cell work. Adenosine triphosphate, or ATP, can lose one or two phosphate groups when water is added. This hydrolysis reaction is exergonic, which means it releases energy that the cell can use. When one phosphate group is removed, ATP becomes ADP, or adenosine diphosphate. Inorganic phosphate is also released. ADP can then be hydrolyzed again to form AMP, or adenosine monophosphate, after a second phosphate group is removed. ATP has a clear structure. It is...

phosphorylation

Phosphorylation and Protein Control

Phosphorylation helps control how proteins work in cells. It is the addition or removal of phosphate groups, and it is the most common chemical change that regulates cellular processes. These changes can alter a protein’s structure, activity, stability, location inside the cell, and interactions with other proteins. During phosphorylation, protein kinases move the terminal phosphate group from ATP to a specific amino acid side chain on a target protein. The amino acids most often...

induced-fit model

How Enzymes Adjust to Their Substrates

Enzymes speed up many chemical reactions in cells. They are biological catalysts, so they increase reaction speed without being consumed or permanently changed. They do this by lowering the activation energy needed to turn reactants into products. Enzymes are proteins that usually work by binding to a substrate, which is the reactant molecule they act on. They show substrate specificity, meaning they bind only certain substrates. This specificity depends mainly on the shape and chemical...

enzyme kinetics

Substrate Effects on Enzyme Rates

Enzyme kinetics examines how enzymes change the rate of a reaction. Enzymes speed reactions by lowering the activation energy of the reactants. The reaction rate is the speed at which an enzyme turns reactants into products, and it can be affected by several factors, including the number of available reactants. Scientists often study enzyme kinetics in a test tube with a fixed amount of enzyme. When more substrate, or reactant, is added, the reaction rate increases because the enzyme can make...

enzyme inhibition

Competitive vs Noncompetitive Inhibitors

Enzyme inhibitors are molecules that reduce enzyme activity by binding to enzymes. Cells use these inhibitors to help regulate normal enzyme function. Drugs and toxins can also block enzymes and change how they work. Some inhibitors bind at the active site, which is the part of the enzyme where the substrate normally fits. Competitive inhibitors do this by occupying the active site and preventing the substrate from binding. If the substrate concentration becomes high enough, it can outcompete...

feedback inhibition

How Cells Control Product Buildup

Cells use enzymes to run biochemical reactions and make the products they need. These reactions are happening constantly, and enzymes speed them up so they happen fast enough to matter. Enzyme activity also has to be regulated. Cells need the right amounts of starting materials, intermediate metabolites, and final products. If these substances build up too much or drop too low, the cell can be harmed. That is why cells use control systems to keep metabolic levels balanced. One important...

allosteric regulation

Allosteric Control of Enzyme Speed

Allosteric control changes enzyme speed when a molecule binds to a site other than the active site. That alternate binding spot is called an allosteric site. An enzyme can have more than one allosteric site. This type of control can raise or lower enzyme activity. Many enzymes with allosteric control are metabolic enzymes. They help with the breakdown or the building of specific molecules in cells. In allosteric inhibition, the effector molecule causes a shape change that lowers the enzyme's...

cofactors and coenzymes

Enzyme helpers are needed for many enzymes to work properly. These helpers fall into two groups: cofactors and coenzymes. Cofactors are metallic ions, while coenzymes are non-protein organic molecules. Both can be tightly bound to an enzyme or attach only when the substrate binds. Cofactors are common in mature proteins, appearing in about 30% of them. They are often added as the enzyme folds and help with catalytic activity. Magnesium is one important cofactor, and it is needed by more than...

key terms and concepts

Learn how cofactors and coenzymes help enzymes work, from magnesium in DNA polymerase to biotin and other vitamin-based helpers.

Enzyme Helpers: Metals, Vitamins, and More | JoVE K12

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Enzyme Helpers: Metals, Vitamins, and More

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