Name: how protein shape determines function
Uploaded: 2023-04-30T18:28:47.000Z
Duration: 2 min 15 s
Channel: JoVE

K12 Standards

Next Generation Science Standards

High School

Life Science

from-molecules-to-organisms-structures-and-processes

From Molecules to Organisms: Structures and Processes

HS-LS1-1

Protein and Protein Structures

Белки это полимеры аминокислот, связанных друг с другом пептидными связями. Большинство белков складываются в определенные трехмерные структуры для выполнения своих функций. Структура белка подразделяется на четыре категории:первичная, вторичная, третичная и четвертичная.Линейная последовательность аминокислот в белке это его первичная структура. Эти последовательности читаются в порядке синтеза полимера, от N-конца свободного амино-конца до С-конца свободного карбоксильного конца. Вторичные структуры образуются за счет водородных связей между кислородом карбонильной группы одной аминокислоты и водородом аминогруппы другой.Обычные вторичные структуры включают в себя альфа-спирали и бета-складчатые листы. Эти и другие соединительные структуры, такие как бета-витки, в дальнейшем взаимодействуют с образованием трехмерной структуры белка, известной как третичная структура. Формирование третичной структуры происходит за счет взаимодействий между R-группами аминокислот.R-группы с противоположными зарядами могут образовывать ионные связи, а сера в двух цистеинах может образовывать ковалентный дисульфидный мостик. Другие факторы включают гидрофобные взаимодействия между гидрофобными боковыми цепями и водородные связи между полярными боковыми цепями. Кроме того, некоторые белки образуют четвертичные структуры, сборки из двух или более полипептидных цепей.Например, гемоглобин это белок, состоящий из четырех субъединиц:двух альфа и двух бета. Ученые могут использовать структуру белка, чтобы предсказать его функцию и расположение в клетке. Белки в цитоплазме клетки имеют на своей поверхности гидрофильные аминокислоты, которые взаимодействуют с водой в цитоплазме и имеют гидрофобные ядра.Напротив, белки, присутствующие в клеточных мембранах, часто имеют на поверхности гидрофобные аминокислоты, которые взаимодействуют с с глицерофосфолипидами в мембране и имеют гидрофильные ядра.

<ol>
	<li>Нельсон, Д. Л., и Кокс, М. М. (2008). Принципы биохимии Ленингера (5-е изд.). У.Х. Фримен. стр. 113-140</li>
	<li>Кристаллическая структура гемоглобина Т-состояния со связанным кислородом на всех четырех гемах.Paoli, M., Liddington, R., Tame, J., Wilkinson, A., Dodson, G. (1996) J Mol Biol 256: 775</li>
</ol>

Белок и белковые структуры

Белки являются одними из самых обильных органических молекул в живых системах и обладают самым разнообразным диапазоном функций всех макромолекул. Белки могут быть структурными, регулятивными, а также быть более или более защитными. Они могут служить в транспорте, хранении или мембранах, или они могут быть токсинами или ферментами. Их структуры, как и их функции, сильно различаются. Все они, однако, аминокислотные полимеры, расположенные в линейной последовательности. 
 Форма белка имеет решающее значение для его функции. Например, фермент может связывать определенный субстрат на своем активном участке. Если этот активный участок был изменен из-за местных изменений или изменений в общей структуре белка, фермент может оказаться не в состоянии связать с субстратом. Чтобы понять, как белок приобретает окончательную форму или конформация, нам необходимо понять четыре уровня структуры белка: Первичный, вторичный, третичный и четвертичный. 
 Основная структура 
 Уникальная последовательность аминокислот в полипептидной цепи является ее основной структурой. Например, инсулин гормона поджелудочной железы имеет две полипептидные цепи, А и в, и они связаны между собой дисульфидными связями. Аминокислота клеммы N цепи A является глицином, в то время как аминокислота клеммы C является спаржей.  Аминокислотные последовательности в цепях A и B уникальны для инсулина. 
 Ген, кодирующий белок, в конечном счете определяет уникальную последовательность каждого белка. Изменение нуклеотидной последовательности области кодирования гена может привести к добавлению другой аминокислоты в растущую цепь полипептидов, что вызовет изменение структуры и функции белка. При серповидной клеточной анемии цепь гемоглобина β имеет одну аминокислотную замену, что вызывает изменение структуры и функции белка. В частности, валин в цепи β заменяет аминокислотную глутаминовую кислоту. Из-за этой смены одной аминокислоты в цепи молекулы гемоглобина образуют длинные волокна, которые искажают биконave, или дисковые, красные кровяные клетки и вызывают у них полумесяц или “серп”, что засоряет кровеносные сосуды. Это может привести к многочисленным серьезным проблемам со здоровьем, таким как дыхание, головокружение, головные боли и боль в животе для тех, кто поражен этой болезнью. 
 Вторичная структура 
 Локальное свертывание полипептида в некоторых регионах приводит к возникновению вторичной структуры белка. Наиболее распространены β-геликоид и α-гофрированные листовые структуры. Обе конструкции удерживаются в форме водородными связями. Водородные связи образуются между атомом кислорода в карбонильной группе в одной аминокислоте и другой аминокислотой, которая является четырьмя аминокислотами дальше по цепи. 
 Каждый спиральный поворот в альфа-спиральной спирали имеет 3.6 аминокислотных остатков. Группы R полипептида (группы вариантов) выступают из цепи α-геликоида. В β-гофрированной оболоке водородное соединение между атомами на магистральной линии полипептида образует «плеэты». Группы R прикреплены к углеродам и выдвигаются выше и ниже складков гофр. Гофрированные сегменты выравниваются параллельно или антипараллельно друг другу, а водородные связи образуют между частично положительным атомом водорода в аминогруппе и частично отрицательным атомом кислорода в карбонильной группе пептидной магистрали. α-геликоид и β-гофрированные листовые структуры находятся в большинстве глобулярных и волокнистых белков, и они играют важную структурную роль. 
 Третичная структура 
 Уникальная трехмерная структура полипептида - это его третичная структура. Эта структура частично обусловлена химическим взаимодействием при работе над полипептидной цепью. В первую очередь, взаимодействия между группами R создают сложную трехмерную третичную структуру белка. Природа R-групп в задействованных аминокислотах может противодействовать формированию водородных связей, которые мы описали для стандартных вторичных структур. Например, группы R с похожими обвинениями отталкиваются друг от друга, а те, у кого нет обвинений, притягиваются друг к другу (ионные связи). Когда происходит свертывание белков, гидрофобные R-группы неполярных аминокислот лежат внутри протеина, тогда как гидрофильные R-группы лежат снаружи. Взаимодействия между боковыми цепями цистеина образуют дисульфидные связи при наличии кислорода, единственной ковалентной связи, образующейся при складывании белка. 
 Все эти взаимодействия, слабые и сильные, определяют окончательную трехмерную форму белка. Когда белок теряет трехмерную форму, он может больше не работать. 
 Четвертичное структура 
 В природе некоторые белки образуют из нескольких полипептидов, или подединиц, и взаимодействие этих подединиц образует четвертичное строение. Слабые взаимодействия между подразделениями помогают стабилизировать общую структуру. Например, инсулин (глобулярный белок) имеет сочетание водородных и дисульфидных связей, которые в основном приводят к образованию мяча. Инсулин начинается как единичный полипептид и теряет некоторые внутренние последовательности при наличии пост-поступательной модификации после формирования дисульфидных связей, которые удерживают остальные цепи вместе. Шелк (волокнистый белок), однако, имеет структуру β-гофрированного листа, которая является результатом водородного соединения между различными цепями. 
 Этот текст был адаптирован из<a href="https://openstax.org/books/biology-2e/pages/3-4-proteins"> Openstax, Biology 2e, Глава 3.4: Белки</a>.

Белки являются одними из самых распространенных органических молекул в живых системах и обладают самым разнообразным спектром функций из всех макромолекул. Белки могут ...

Education

JoVE Core

Cell Biology

Клеточная биология

Unit 1

Раздел 1

Biochemistry of the Cell

Биохимия клетки

KEY TERMS AND CONCEPTS

ОСНОВНЫЕ ТЕРМИНЫ И ПОНЯТИЯ

how protein shape determines function

Proteins are essential molecules in living things, and their shape affects how they work. Protein structure is described at several levels, including primary, secondary, tertiary, and quaternary structure. These levels help explain how a protein is built and how its final form supports its job.

Primary structure is the sequence of amino acids in a protein. Secondary structure forms when parts of the chain fold into regular patterns. Tertiary structure is the overall three-dimensional shape of one protein chain. Quaternary structure appears when more than one protein chain joins together to make a working protein.

The video also shows how protein structure can be represented in different ways. A simple line drawing can show the amino acid sequence. Other models can show folding and the full 3D shape. These visual forms help students compare levels of structure and see why protein shape matters.

How Protein Shape Determines Function

the periodic table and organismal elements

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Elements in the Human Body and Periodic Table

Elements are the smallest units of matter that cannot be broken down further by chemical processes. Scientists know 118 elements, but not all of them occur naturally. Only a small number are essential for life, and living matter depends mostly on carbon, nitrogen, hydrogen, and oxygen. The periodic table organizes elements by their physical and chemical properties. Each square shows the element name, chemical symbol, atomic number, and atomic weight. The atomic number is the number of protons...

functional groups

Functional Groups in Organic Molecules

Functional groups are the part of an organic molecule that gives it specific chemical behavior. They help explain why compounds with similar carbon skeletons can react in different ways. In organic chemistry, these groups are often used to classify compounds. A functional group can change the properties of a molecule and affect how it behaves in a reaction. Knowing functional groups helps students recognize patterns in organic compounds. It also makes it easier to compare molecules that share...

types of chemical bonds

Chemical Bonds and How Atoms Join

Chemical bonds hold atoms together and help explain how different substances form. In chemistry, the main bond types are ionic bonds, covalent bonds, and metallic bonds. Ionic bonds form when electrons move from one atom to another. Covalent bonds form when atoms share electrons. Metallic bonds occur in metals, where electrons are held in a shared arrangement that gives metals their characteristic behavior. Understanding these bond types helps students compare how atoms connect in different...

noncovalent attractions in biomolecules

Biomolecule Interactions Without Covalent Bonds

Biomolecules often stay together through noncovalent attractions instead of covalent bonds. These weaker interactions help molecules recognize each other and form structures needed for life. The main noncovalent attractions are hydrogen bonds, electrostatic interactions, van der Waals forces, and hydrophobic interactions. Each one works in a different way, but all of them can influence how biomolecules fold, bind, and behave in cells. Hydrogen bonds form when a hydrogen atom is attracted to...

polymers

Polymer Chains and Their Properties

Polymers are large molecules made from repeating units called monomers. These long chains can form many common materials. Their structure helps explain why different polymers can behave in different ways. Polymers can be built in more than one way. Some form by addition polymerization, where monomers join together directly. Others form by condensation polymerization, which releases a small molecule as the chain grows. The type of polymer affects its properties and uses. Some polymers are...

what are lipids?

Lipids in Cells: Membranes, Energy, and Signals

Lipids are important cell molecules that act as membrane parts, energy stores, and signaling molecules. They are a diverse group of hydrocarbons, which are compounds made of carbon and hydrogen atoms. The carbon-carbon and carbon-hydrogen bonds are nonpolar, so lipids have an overall nonpolar character. Lipids are also hydrophobic, or “water-hating.” They do not form hydrogen bonds with water, so they are nearly insoluble in water. They are, however, soluble in organic solvents such as...

structure of lipids

How Lipid Molecules Are Built

Lipid molecules are built from hydrocarbon chains and a few key structural parts. Their shape helps explain why they behave differently from many other biological molecules. In high school biology, this structure is often linked to how lipids store energy and help form cell membranes. Some lipids are made from fatty acids joined to other small molecules. Triglycerides contain glycerol and three fatty acids, while phospholipids contain glycerol, two fatty acids, and a phosphate group. These...

chemistry of carbohydrates

Carbohydrate Structure and Bonding

Carbohydrates are built from sugar units and the bonds that link them. Their chemistry explains how simple sugars join to form larger molecules. It also helps show why carbohydrates have different structures and functions. The video focuses on the main sugar types found in carbohydrates. These include monosaccharides, disaccharides, and polysaccharides. Monosaccharides are single sugar units. Disaccharides contain two sugar units, while polysaccharides are long chains of many sugar units. The...

nucleic acids

DNA and RNA in Cells

DNA and RNA are nucleic acids that help store and use genetic information in cells. They are key molecules in biology and are often studied together because they work as a pair in living systems. Nucleic acids are built from repeating units called nucleotides. Each nucleotide has a sugar, a phosphate group, and a nitrogenous base. The order of these bases carries the genetic code. There are two main nucleic acids: DNA, or deoxyribonucleic acid, and RNA, or ribonucleic acid. DNA usually stores...

protein and protein structures

Proteins are essential molecules in living things, and their shape affects how they work. Protein structure is described at several levels, including primary, secondary, tertiary, and quaternary structure. These levels help explain how a protein is built and how its final form supports its job. Primary structure is the sequence of amino acids in a protein. Secondary structure forms when parts of the chain fold into regular patterns. Tertiary structure is the overall three-dimensional shape of...

ph regulation in cells

Cell pH and Organelle Balance

Cell pH and organelle balance are essential for normal cell function. pH affects protein shape and activity, the charge on cell membranes, and many metabolic reactions inside the cell. Cells also use the proton motive force, which is the energy stored in a proton gradient, to make ATP, the cell’s main energy molecule. The cytosol, or fluid inside the cell, is usually slightly more acidic than the fluid outside the cell. Even so, cells must stop the cytosol from becoming too acidic. They use...

chemistry of the cell

Cell Chemistry: Water, Ions, and Molecules

Cell chemistry explains the substances that make cells work. Water is the main component of cells, and it supports the chemical reactions that keep life going. Cells also contain organic molecules, which are carbon-based compounds, and inorganic ions, which are charged particles needed for cell function. Organic molecules in cells include carbohydrates, lipids, proteins, and nucleic acids. These molecules have different roles, but together they build cell structures, store energy, and carry...

key terms and concepts

Learn how proteins are built and folded through primary, secondary, tertiary, and quaternary structure, and how protein shape affects function.

How Protein Shape Determines Function | JoVE K12

cell biology

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.

Florida Department of Education

SC.912.L.18

SC.912.L.18.1

SC.912.L.18.4

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New York State Science Learning Standards

Structure and Function

HS-LS1-1.

Georgia Standards of Excellence

9-12

Biology

SB6.c

Characteristics of Life

Biology is a natural science that studies life and living organisms, including their structure, function, development, interactions, evolution, ...

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Cell Structure

Background
Cells represent the most basic biological units of all organisms, whether it be simple, single-celled organisms like bacteria, or large, ...

Visualizing Onion and Cheek Cells
ExpandImmediately before the experiment, wash and peel onion bulbs for the class.
Remove the entire brown outer skin and ...

Visualizing Onion and Human Cells
ExpandIn this experiment you will prepare different types of cells from a plant and animal, onion and human ...

What are Cells?

Cell Diversity

The concept of a cell started with microscopic observations of dead cork tissue by Robert Hooke in 1665. Hooke coined the term &#34;cell&#34; based on the ...

Cytoplasm

The cytoplasm consists of organelles and a framework of protein scaffolds called the cytoskeleton suspended in an aqueous solution, the cytosol. The ...

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 ...

The Central Dogma

The DNA Helix

Nucleic Acids

DNA as a Genetic Template

Structure of a Gene

A gene is the fundamental unit of heredity. Every individual has two copies of each gene, one inherited from each parent. Although most people contain the ...

Chromosome Structure

Base-pairing and DNA Repair

What is Gene Expression?

A gene is a stretch of DNA that serves as the blueprint for functional RNAs and proteins. Since DNA is comprised&#160; of nucleotides and proteins are ...

RNA Structure

The basic structure of RNA consists of a string of ribonucleotides attached by phosphodiester bonds. Although most RNA is single-stranded, it can form ...

Protein Families

Types of RNA

Three main types of RNA are involved in protein synthesis: messenger RNA (mRNA), transfer RNA (tRNA), and ribosomal RNA (rRNA). These RNAs perform diverse ...

Conservation of Protein Domains

Transcription

Transcription is the synthesis of RNA from a DNA sequence by RNA polymerase. It is the first step in producing a protein from a gene sequence. ...

Globular and Fibrous Proteins

Translation

Translation is the process of synthesizing proteins from the genetic information carried by messenger RNA (mRNA). Following transcription, it constitutes ...

Intrinsically Disordered Proteins

Ribosomes

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

Protein Complex Assembly

Conjugated Proteins

Proteins: From Genes to Degradation

Amyloid Fibrils

What are Proteins?

Proteins are polymers of amino acids linked together by peptide bonds. Proteins and polypeptides are interchangeably used to refer to long chains of amino ...

Ligand Binding Sites

Protein Organization

Proteins are polymers of amino acid residues. They are versatile and responsible for different cellular functions, including DNA replication, molecular ...

Protein-Protein Interfaces

Protein Folding

Proteins are chains of amino acids linked together by peptide bonds. Upon synthesis, a protein folds into a three-dimensional conformation, critical to ...

Conserved Binding Sites

Cofactors and Coenzymes

Enzymes are proteins made of amino acids. The functional group of each constituent amino acid catalyzes a wide variety of chemical reactions via ionic ...

Cooperative Allosteric Transitions

Protein Kinases and Phosphatases

GTPases and their Regulation

Covalently Linked Protein Regulators

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Protein Complexes with Interchangeable Parts

Mechanical Protein Function

Structural Protein Function

Protein Networks

Construct an explanation based on evidence for how the structure of DNA determines the structure of proteins, which carry out the essential functions of life through systems of specialized cells. [Assessment Boundary: Assessment does not include identification of specific cell or tissue types, whole body systems, specific protein structures and functions, or the biochemistry of protein synthesis.]

Levels of Organization

Biological organization is the classification of biological structures, ranging from atoms at the bottom of the hierarchy to the Earth&#x27;s biosphere. ...

Animal and Plant Cell Structure

Animal and plant cells not only differ in their structure, function, and mode of nutrition but also in how they reproduce, specialize, and organize into ...

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Structural Organization of the Human Body: An Overview

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Overview of Human Digestion

The human body contains a monogastric digestive system. In a monogastric digestive system, the stomach only contains one chamber in which it digests food. ...

Anatomy of the Intestines

Although digestion of proteins, carbohydrates, and lipids may begin in the stomach, it is completed in the intestine. The absorption of nutrients, water, ...

Accessory Organs

Accessory organs are those that participate in the digestion of food but do not come into direct contact with it like the mouth, stomach, or intestine do. ...

Lipid Digestion

Lipids are large molecules that are generally not water-soluble. Since most of the digestive enzymes in the human body are water-based, there are specific ...

Protein Digestion

Protein digestion begins in the stomach, where the highly acidic environment can easily disrupt protein structure by exposing the peptide bonds of ...

Carbohydrate Digestion

Carbohydrate digestion and metabolism break down simple and complex carbohydrates from food into saccharides (i.e., sugars) for the body to use as energy. ...

What is a Nervous System?

Overview

The nervous system is the collection of specialized cells responsible for maintaining an organism&rsquo;s internal environment and coordinating ...

The Parasympathetic Nervous System

Overview

The parasympathetic nervous system is one of the two major divisions of the autonomic nervous system. This parasympathetic system is responsible ...

The Sympathetic Nervous System

Overview

The sympathetic nervous system&mdash;one of the two major divisions of the autonomic nervous system&mdash;is activated in times of stress. It ...

Oogenesis

In human women, oogenesis produces one mature egg cell or ovum for every precursor cell that enters meiosis. This process differs in two unique ways from ...

What is a Sensory System?

Sensory systems detect stimuli&mdash;such as light and sound waves&mdash;and transduce them into neural signals that can be interpreted by the nervous ...

Fertilization

During fertilization, an egg and sperm cell fuse to create a new diploid structure. In humans, the process occurs once the egg has been released from the ...

What is the Skeletal System?

Overview

The adult human skeleton comprises 206 bones that are connected through cartilage, tendons, and ligaments. The skeleton provides a rigid ...

an-introduction-to-the-zebrafish-danio-rerio

An Introduction to the Zebrafish: Danio rerio

Zebrafish (Danio rerio) are small freshwater fish that are used as model organisms for biomedical research. The many strengths of these fish include their ...

Physiology of the Circulatory System

Homeostasis
Conditions in the external environment of an organism can change rapidly and drastically. To survive, organisms must maintain a fairly ...

Anatomy of the Circulatory System

The human circulatory system consists of blood, blood vessels that carry blood away from the heart, around the body, and back to the heart, and the heart ...

Measuring Blood Pressure
ExpandTo prepare for the blood pressure exercise, simply place the appropriate number of alcohol swabs, sphygmomanometers, and ...

Anatomy of the Heart

The human heart is made up of three layers of tissue that are surrounded by the pericardium, a membrane that protects and confines the heart. The ...

Measuring Circulatory System Function in Humans
ExpandBefore starting the experiment go to the front of the room and collect an alcohol swab, a ...

Blood Flow

Blood is pumped by the heart into the aorta, the largest artery in the body, and then into increasingly smaller arteries, arterioles, and capillaries. The ...

What Are Osmoregulation and Excretion?

Organisms must keep bodily fluids at a constant temperature and pH while maintaining specific solute concentrations in order to support life functions. ...

Blood Withdrawal I

Source: Kay Stewart, RVT, RLATG, CMAR; Valerie A. Schroeder, RVT, RLATG. University of Notre Dame, IN
Blood collection is a common requirement for ...

Kidney Structure

The kidneys are two large bean-shaped organs located in the upper abdomen. They filter the blood several times a day to remove toxins and rebalance water ...

Blood Withdrawal II

Source: Kay Stewart, RVT, RLATG, CMAR; Valerie A. Schroeder, RVT, RLATG. University of Notre Dame, IN
The collection of blood from mice and rats for ...

What is the Immune System?

Overview

The immune system comprises diverse biological structures and processes that protect the body from disease. These processes can be classified ...

Bone Remodeling

Bone remodeling is a continuous and balanced process of bone resorption by osteoclasts and bone formation by osteoblasts. In adults, it helps maintain ...

Spermatogenesis

Spermatogenesis is the process by which haploid sperm cells are produced in the male testes. It starts with stem cells located close to the outer rim of ...

Develop and use a model to illustrate the hierarchical organization of interacting systems that provide specific functions within multicellular organisms. [Clarification Statement: Emphasis is on functions at the organism system level such as nutrient uptake, water delivery, and organism movement in response to neural stimuli. An example of an interacting system could be an artery depending on the proper function of elastic tissue and smooth muscle to regulate and deliver the proper amount of blood within the circulatory system.] [Assessment Boundary: Assessment does not include interactions and functions at the molecular or chemical reaction level.]

HS-LS1-2

How Protein Shape Determines Function

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