Name: protein folding levels and bonds
Uploaded: 2023-04-30T10:34:07.000Z
Duration: 1 min 24 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 Organization

Durante la traduzione, una catena di amminoacidi che emerge dal ribosoma forma la struttura proteica primaria. Questa catena peptidica è tenuta insieme da legami covalenti tra le estremità amminiche e carbossiliche di due amminoacidi.
Alcuni amminoacidi creano legami idrogeno con i loro vicini per formare strutture secondarie stabili come alfa eliche e beta-fogli.
Le alfa-eliche sono strutture a spirale tenute insieme da legami idrogeno tra l'ossigeno carbonilico e l'idrogeno ammidico di ogni quarto residuo amminoacidico di una catena polipeptidica.
I beta-sheet sono strutture polipeptidiche a zig-zag formate quando sezioni della catena polipeptidica interagiscono lateralmente attraverso il legame idrogeno.
Ulteriori interazioni chimiche tra catene laterali di amminoacidi distanti o la spina dorsale del peptide, come le forze idrofobiche, il legame ionico e i ponti disolfuro, aiutano il polipeptide a ripiegarsi nella struttura terziaria. Questa forma 3D è la forma funzionale finale per molte proteine.
Se due o più catene polipeptidiche si combinano dalla struttura terziaria in un complesso più grande, si crea una struttura quaternaria. Questi possono essere complessi omomerici o eteromerici con funzioni cellulari distinte.

<ol>
	<li>Sanvictores T, Farci F. Biochimica, struttura delle proteine primarie. [Aggiornato il 5 novembre 2021]. In: StatPearls [Internet]. L'isola del tesoro (FL): StatPearls Publishing; 2022 gennaio-. Disponibile da: <a href="https://www.ncbi.nlm.nih.gov/books/NBK564343/">https://www.ncbi.nlm.nih.gov/books/NBK564343/</a></li>
	<li>Abualia, Mohammed, Lianne Schroeder, Megan Garcia, Patrick L. Daubenmire, Donald J. Wink e Ginevra A. Clark. "Collegamento della struttura proteica alle interazioni intermolecolari: un laboratorio di modellazione computerizzata". Journal of Chemical Education 93, n. 8 (2016): 1353-1363.</li>
</ol>

organizzazione delle proteine

Le proteine sono polimeri di residui di amminoacidi. Sono versatili e responsabili di diverse funzioni cellulari, tra cui la replicazione del DNA, il trasporto molecolare, la catalisi e il supporto strutturale. Le proteine hanno una struttura gerarchica comprendente almeno tre livelli di organizzazione: struttura primaria, secondaria e terziaria. Alcune grandi proteine hanno una struttura quaternaria in cui le singole subunità proteiche sono collegate insieme.

La struttura primaria di una proteina è la sua sequenza di aminoacidi. Gli amminoacidi sono collegati attraverso legami peptidici per formare una catena polipeptidica con due estremità: l'ammino-terminale (N-terminale) e il carbossi-terminale (C-terminale). La sequenza degli amminoacidi determina la forma ripiegata finale della proteina. Venti diversi aminoacidi sono disposti in sequenze diverse per creare una varietà di polipeptidi.

La struttura secondaria si riferisce alle regioni ripiegate localmente delle catene di amminoacidi che sono stabilizzate da legami idrogeno. Esistono due tipi di strutture secondarie: alfa-eliche e fogli beta-pieghettati. Questi elementi strutturali secondari sono collegati da semplici anelli.

Man mano che le strutture secondarie si assemblano ulteriormente, viene generata la forma ripiegata finale della proteina. Tale struttura tridimensionale o terziaria di una proteina è stabilizzata dalle interazioni tra le catene laterali degli amminoacidi. I legami idrogeno, le forze elettrostatiche, i legami disolfuro e le forze di Vander Waals stabilizzano la forma piegata, che spesso è lo stato nativo o funzionale della proteina.

Quando due o più catene polipeptidiche ripiegate chiamate subunità proteiche formano un complesso, viene creata una struttura proteica quaternaria.

Organizzazione delle proteine

Le proteine sono polimeri di residui di amminoacidi. Sono versatili e responsabili di diverse funzioni cellulari, tra cui la replicazione del DNA, ...

Education

Didattica

JoVE Core

Cell Biology

Biologia cellulare

Unit 1

Unità 1

Protein Structure

Struttura delle proteine

KEY TERMS AND CONCEPTS

TERMINI E CONCETTI CHIAVE

protein folding levels and bonds

Proteins are built from amino acids and folded into shapes that support many cell jobs. They help with DNA replication, molecular transport, catalysis, and structural support. Their function depends on how their amino acids are arranged and folded.

Protein structure is organized in levels. The primary structure is the amino acid sequence in a polypeptide chain. Amino acids are joined by peptide bonds, and the chain has two ends: the amino terminus, or N-terminus, and the carboxyl terminus, or C-terminus. Twenty different amino acids can be arranged in many sequences to make a wide variety of polypeptides.

The secondary structure forms when parts of the chain fold locally. These regions are stabilized by hydrogen bonds. The two main secondary structures are alpha-helices and beta-pleated sheets. Simple loops connect these folded sections.

The tertiary structure is the full three-dimensional fold of one polypeptide chain. It is stabilized by interactions between amino acid side chains. Hydrogen bonds, electrostatic forces, disulfide linkages, and Vander Waals forces help hold the folded protein in its native, functional state.

Some proteins form a quaternary structure. This happens when two or more folded polypeptide chains, called protein subunits, join together into one complex. Large proteins can use this higher level of organization to work as a unit.

Protein Folding Levels and Bonds

what are proteins?

Protein Building Blocks and Folding

Proteins are built from amino acids linked by peptide bonds. Long chains of amino acids are often called polypeptides, and the terms proteins and polypeptides are sometimes used the same way. In this context, polypeptides with a molecular weight below 10,000 daltons are called polypeptides, while proteins have a higher molecular weight. Very short chains with fewer than 20 amino acids are called peptides or oligopeptides. Amino acids are the basic units of proteins. Each amino acid has a...

protein organization

Proteins are built from amino acids and folded into shapes that support many cell jobs. They help with DNA replication, molecular transport, catalysis, and structural support. Their function depends on how their amino acids are arranged and folded. Protein structure is organized in levels. The primary structure is the amino acid sequence in a polypeptide chain. Amino acids are joined by peptide bonds, and the chain has two ends: the amino terminus, or N-terminus, and the carboxyl terminus, or...

protein folding

How Amino Acid Sequence Shapes Proteins

Proteins get their shape from the order of amino acids in a polypeptide chain. After a protein is made, the chain folds into a three-dimensional form that is needed for it to work. The way amino acids interact with one another guides this folding. Protein structure matters because proteins do many jobs in cells. They can speed up chemical reactions, help with immune defense, store materials, carry substances, send cell signals, support movement, and provide structure. A protein usually works...

protein families

Protein Families and Superfamilies

Protein families and superfamilies group proteins with shared features. These groups help scientists organize proteins by common structure, function, or evolutionary history. The classification can show how related proteins are connected across different organisms. A protein family usually includes proteins that are closely related. A superfamily is a broader group that can include several families with more distant relationships. These categories help explain why some proteins share similar...

conservation of protein domains

Protein Domains Shared Across Proteins

Protein domains are shared structural and functional parts of proteins. A domain is a region that can often be found in more than one protein, even when the full proteins are different. This conservation means that a protein domain may keep a similar shape or role across related proteins. Because of that, scientists can compare proteins by looking for domains that stay the same. Conserved domains help reveal how proteins are related and how they may work. The topic of protein domain...

globular and fibrous proteins

Protein Shapes: Globular vs Fibrous

Proteins can have globular or fibrous shapes, and these shapes help explain how they work in the body. Globular proteins are compact and usually fold into rounded forms. Fibrous proteins are long, extended molecules that often provide support and structure. The shape of a protein is tied to its function. Globular proteins often take part in chemical jobs in cells, while fibrous proteins are better suited for strength and stability. These structural differences make the two groups easy to...

intrinsically disordered proteins

Flexible Protein Regions and Disorder

Intrinsically disordered proteins have flexible regions that do not settle into one fixed shape. Instead, these proteins can remain dynamic and change form as they move through the cell. This flexibility is an important part of their structure and function. Many proteins need a stable folded shape to work properly. Intrinsically disordered proteins are different because they may lack a single rigid structure under normal conditions. Their shifting shape can help them take part in cell...

protein complex assembly

Protein Complex Formation and Function

Protein complex formation explains how proteins join together to carry out specific jobs in cells. These groups are called protein complexes, and they can form in more than one way. Some complexes are homomeric, which means they contain the same kind of protein subunit. Others are heteromeric, which means they contain different protein subunits. The assembly process helps show how protein shape and subunit choice affect function. When proteins combine, the resulting complex can behave...

conjugated proteins

Conjugated Proteins and Their Bound Groups

Conjugated proteins are proteins that include a nonprotein part called a prosthetic group. This added group helps give the protein its full structure or function. The video explains how the protein part and the bound group work together. Several common types of conjugated proteins are named by the kind of group attached. Nucleoproteins contain nucleic acids. Glycoproteins contain carbohydrate groups, and lipoproteins contain lipid groups. Other examples include phosphoproteins, which have...

amyloid fibrils

Amyloid Fibrils and Protein Aggregation

Amyloid fibrils are protein aggregates with a very specific structure. They are made when proteins misfold and stick together in long, ordered fibers. This structure makes them different from many other protein clumps. Amyloid fibrils are important in biology because they are linked to protein aggregation. Protein aggregation means proteins build up into groups instead of staying properly folded and separate. In many cases, this process is associated with disease and abnormal cell function. <br...

key terms and concepts

Explore protein folding from amino acid sequence to alpha-helices, beta-pleated sheets, tertiary shape, and quaternary protein subunits.

Protein Folding Levels and Bonds | 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.

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What is Homeostasis?

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Homeostatic Imbalance

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pH Homeostasis

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HS-LS1-3

Protein Folding Levels and Bonds

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