Protein: Difference between revisions

Latest revision as of 03:41, 22 March 2025

Molecular model of myoglobin, a protein that stores oxygen in muscle tissue.

Illustration of a peptide bond formed between two amino acids.

Historic model of myoglobin structure as determined by John Kendrew, the first protein structure solved by X-ray crystallography.

File:Peptide-Figure-Revised.png

Revised figure showing the chemical structure of a peptide with labeled components.

File:Peptide group resonance.png

Diagram showing resonance structures in a peptide group, contributing to its planarity.

File:Ribosome mRNA translation en.svg

Schematic of mRNA translation by the ribosome, showing how peptides are synthesized in cells.

A comprehensive overview of proteins, their structure, function, and importance in biological systems.

Proteins are large, complex molecules that play many critical roles in the body. They are essential for the structure, function, and regulation of the body's tissues and organs. Proteins are made up of hundreds or thousands of smaller units called amino acids, which are attached in long chains. There are 20 different types of amino acids that can be combined to make a protein.

Structure[edit]

Proteins are made up of one or more long chains of amino acids, which are called polypeptides. The sequence of amino acids determines each protein’s unique 3-dimensional structure and its specific function. Proteins can be classified into four levels of structure:

Primary Structure[edit]

The primary structure of a protein is its unique sequence of amino acids. This sequence is determined by the gene corresponding to the protein.

Secondary Structure[edit]

The secondary structure refers to local folded structures that form within a polypeptide due to interactions between atoms of the backbone. The most common types of secondary structures are the alpha helix and the beta pleated sheet.

Tertiary Structure[edit]

The tertiary structure is the overall three-dimensional structure of a polypeptide. It is determined by interactions among various side chains (R groups) of the amino acids.

Quaternary Structure[edit]

Some proteins are made up of multiple polypeptide chains, also known as subunits. The quaternary structure is the arrangement of these subunits in a multi-subunit complex.

Function[edit]

Proteins perform a vast array of functions within organisms, including:

Enzymatic activity: Proteins that act as enzymes speed up chemical reactions in the body.
Structural support: Proteins like collagen provide structural support to cells and tissues.
Transport and storage: Proteins such as hemoglobin transport oxygen in the blood.
Signaling: Proteins are involved in cell signaling and communication.
Immune response: Antibodies are proteins that help protect the body from pathogens.

Synthesis[edit]

Protein synthesis is a complex process that involves transcription and translation. During transcription, a segment of DNA is copied into mRNA, which is then translated into a polypeptide chain at the ribosome.

Dietary Proteins[edit]

Proteins are an essential part of the diet. They provide the amino acids that the body cannot synthesize on its own. Dietary proteins can be found in both animal and plant sources, such as meat, fish, eggs, dairy products, legumes, and nuts.

Gallery of Protein and Peptide Structures[edit]

Table of the genetic code showing codon-amino acid correspondence.

Table of the genetic code showing codon-amino acid correspondence.
Diagram of peptide synthesis, illustrating step-by-step chemical formation of peptide bonds.

Diagram of peptide synthesis, illustrating step-by-step chemical formation of peptide bonds.
Structure of a chaperonin protein that assists in the proper folding of other proteins.

Structure of a chaperonin protein that assists in the proper folding of other proteins.
Visualization of a protein’s tertiary structure, using PDB entry 1TIM as an example.

Visualization of a protein’s tertiary structure, using PDB entry 1TIM as an example.
Composite image showing a variety of protein structural motifs and folding patterns.

Composite image showing a variety of protein structural motifs and folding patterns.
Schematic showing domain organization in EVH proteins, involved in actin regulation.

Schematic showing domain organization in EVH proteins, involved in actin regulation.

Related pages[edit]

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-'''Protein''' is a fundamental class of [[biomolecule]]s present in all living organisms. Proteins are composed of one or more long chains of [[amino acid]] residues. They play a critical role in virtually all biological processes, including [[cell structure]] and [[function]], [[enzyme]] catalysis, [[cell signaling]], and [[immune response]]. The shape and structure of a protein determine its function. Proteins can be classified based on their function, structure, and solubility.
+[[File:Myoglobin.png|Molecular model of myoglobin, a protein that stores oxygen in muscle tissue.|thumb]]
+[[File:Peptide_bond.jpg|Illustration of a peptide bond formed between two amino acids.|thumb]]
+[[File:KendrewMyoglobin.jpg|Historic model of myoglobin structure as determined by John Kendrew, the first protein structure solved by X-ray crystallography.|left|thumb]]
+[[File:Peptide-Figure-Revised.png|Revised figure showing the chemical structure of a peptide with labeled components.|thumb]]
+[[File:Peptide_group_resonance.png|Diagram showing resonance structures in a peptide group, contributing to its planarity.|left|thumb]]
+[[File:Ribosome_mRNA_translation_en.svg|Schematic of mRNA translation by the ribosome, showing how peptides are synthesized in cells.|thumb]]
+{{Short description|A comprehensive overview of proteins, their structure, function, and importance in biological systems.}}
+[[Proteins]] are large, complex molecules that play many critical roles in the body. They are essential for the structure, function, and regulation of the body's tissues and organs. Proteins are made up of hundreds or thousands of smaller units called [[amino acids]], which are attached in long chains. There are 20 different types of amino acids that can be combined to make a protein.
 ==Structure==
-Proteins are made up of [[amino acid]]s linked together by peptide bonds in a linear chain. This chain folds into a three-dimensional structure, which is essential for its function. The structure of proteins can be described at four levels:
+Proteins are made up of one or more long chains of amino acids, which are called [[polypeptides]]. The sequence of amino acids determines each protein’s unique 3-dimensional structure and its specific function. Proteins can be classified into four levels of structure:
-* '''Primary structure''' - the sequence of amino acids in the polypeptide chain.
-* '''Secondary structure''' - local structures formed by hydrogen bonding within the polypeptide chain, such as [[alpha helix|α-helices]] and [[beta sheet|β-sheets]].
+===Primary Structure===
-* '''Tertiary structure''' - the overall three-dimensional structure of a single protein molecule.
+The primary structure of a protein is its unique sequence of amino acids. This sequence is determined by the [[gene]] corresponding to the protein.
-* '''Quaternary structure''' - the structure formed by several protein molecules (polypeptide chains), usually called protein subunits, which function as a single protein complex.
+===Secondary Structure===
+The secondary structure refers to local folded structures that form within a polypeptide due to interactions between atoms of the backbone. The most common types of secondary structures are the [[alpha helix]] and the [[beta pleated sheet]].
+===Tertiary Structure===
+The tertiary structure is the overall three-dimensional structure of a polypeptide. It is determined by interactions among various side chains (R groups) of the amino acids.
+===Quaternary Structure===
+Some proteins are made up of multiple polypeptide chains, also known as subunits. The quaternary structure is the arrangement of these subunits in a multi-subunit complex.
 ==Function==
-Proteins perform a vast array of functions within organisms. Some of the key functions include:
+Proteins perform a vast array of functions within organisms, including:
-* '''Enzymatic activity''' - Many proteins act as [[enzyme]]s, speeding up chemical reactions without being consumed in the process.
-* '''Structural support''' - Proteins like [[collagen]], [[keratin]], and [[elastin]] provide structural support to cells and tissues.
-* '''Transport and storage''' - Proteins such as [[hemoglobin]] transport oxygen in the blood, while others store essential molecules for later use.
-* '''Signal transduction''' - Proteins are involved in transmitting signals within and between cells.
-* '''Immune response''' - Antibodies are proteins that bind to specific foreign particles, such as viruses and bacteria, to help protect the body.
-* '''Cell adhesion''' - Proteins are involved in binding cells together and to the extracellular matrix.
-==Synthesis and Degradation==
+* '''Enzymatic activity''': Proteins that act as [[enzymes]] speed up chemical reactions in the body.
-Protein synthesis, or [[translation (biology)|translation]], occurs in the [[ribosome]]s of cells, where genetic information encoded in [[messenger RNA]] (mRNA) is translated into a specific sequence of amino acids. The process of protein synthesis is highly regulated and involves several steps, including initiation, elongation, and termination. After synthesis, proteins can undergo post-translational modifications, which can affect their function and activity.
+* '''Structural support''': Proteins like [[collagen]] provide structural support to cells and tissues.
+* '''Transport and storage''': Proteins such as [[hemoglobin]] transport oxygen in the blood.
+* '''Signaling''': Proteins are involved in cell signaling and communication.
+* '''Immune response''': [[Antibodies]] are proteins that help protect the body from pathogens.
-Proteins are constantly being degraded and synthesized. Protein degradation involves breaking down proteins into their constituent amino acids, a process that is essential for regulating protein function and freeing amino acids for the synthesis of new proteins.
+==Synthesis==
+Protein synthesis is a complex process that involves [[transcription]] and [[translation]]. During transcription, a segment of DNA is copied into [[mRNA]], which is then translated into a polypeptide chain at the [[ribosome]].
-==Nutritional Aspects==
+==Dietary Proteins==
-Dietary proteins are an essential part of human nutrition, providing the amino acids needed for the synthesis of body proteins. Essential amino acids cannot be synthesized by the body and must be obtained from the diet. Animal sources of protein, such as meat, fish, eggs, and dairy, are considered complete proteins because they contain all the essential amino acids. Plant sources of protein can be combined to provide all the essential amino acids.
+Proteins are an essential part of the diet. They provide the amino acids that the body cannot synthesize on its own. Dietary proteins can be found in both animal and plant sources, such as meat, fish, eggs, dairy products, legumes, and nuts.
-==Diseases Related to Proteins==
+==Gallery of Protein and Peptide Structures==
-Protein misfolding and aggregation are associated with a range of diseases, including [[Alzheimer's disease]], [[Parkinson's disease]], and [[Huntington's disease]]. These conditions are often referred to as proteinopathies or conformational diseases. In addition, deficiencies in or mutations of specific proteins can lead to diseases such as [[sickle cell anemia]] (a mutation in the hemoglobin protein) and [[cystic fibrosis]] (a defect in the CFTR protein).
-[[Category:Biochemistry]]
-[[Category:Proteins]]
-{{stb}}
 <gallery>
-File:Myoglobin.png|Protein
+File:Genetic_code.svg|Table of the genetic code showing codon-amino acid correspondence.
-File:Peptide_bond.jpg|Protein
+File:Peptide_Synthesis.svg|Diagram of peptide synthesis, illustrating step-by-step chemical formation of peptide bonds.
-File:KendrewMyoglobin.jpg|Protein
+File:Chaperonin_1AON.png|Structure of a chaperonin protein that assists in the proper folding of other proteins.
-File:Peptide-Figure-Revised.png|Protein
+File:Proteinviews-1tim.png|Visualization of a protein’s tertiary structure, using PDB entry 1TIM as an example.
-File:Peptide_group_resonance.png|Protein
+File:Protein_composite.png|Composite image showing a variety of protein structural motifs and folding patterns.
-File:Ribosome_mRNA_translation_en.svg|Protein
+File:Domain_organisation_of_EVH_proteins.png|Schematic showing domain organization in EVH proteins, involved in actin regulation.
-File:Genetic_code.svg|Protein
-File:Peptide_Synthesis.svg|Protein
-File:Chaperonin_1AON.png|Protein
-File:Proteinviews-1tim.png|Protein
-File:Protein_composite.png|Protein
-File:Domain_organisation_of_EVH_proteins.png|Protein
 </gallery>
+==Related pages==
+* [[Amino acid]]
+* [[Enzyme]]
+* [[Gene expression]]
+* [[Metabolism]]
+[[Category:Proteins]]