Quote: "Proteins are large biomolecules and macromolecules that comprise one or more long chains of amino acid residues. Proteins perform a vast array of functions within organisms, including catalysing metabolic reactions, DNA replication, responding to stimuli, providing structure to cells and organisms, and transporting molecules from one location to another."
Proteins are crucial in molecular biology since they are the building blocks of cells and play important roles in cell signaling and gene expression. This includes the different types of proteins and their roles in cells.
Amino acids: The building blocks of proteins. Understanding the 20 different amino acids and their properties is crucial in understanding protein structure and function.
Protein structure: The hierarchy of protein structure—primary, secondary, tertiary, and quaternary—determines the function of proteins. The unique folding and shape of a protein are essential for its biological activity.
Protein domains: Discrete regions of a protein that fold independently and have a specific function. These domains are often shared among many proteins and are critical in determining protein interactions.
Protein synthesis: The process by which cells build proteins using DNA as a template. Understanding how proteins are made is essential in understanding their function.
Protein purification: Isolating a protein from a complex mixture is a critical step in studying its structure and function. Various techniques are used to purify proteins.
Enzymes: Proteins that catalyze biochemical reactions. Enzymes lower the activation energy required for a reaction to occur and are essential for many biological processes.
Protein-ligand interactions: The binding of a protein to a small molecule or ligand is critical in determining a protein's function. Understanding these interactions is essential for drug design and development.
Protein-protein interactions: Proteins often interact with other proteins to carry out their biological functions. Understanding these interactions is crucial in understanding cell signaling and many other processes.
Protein folding and misfolding: Proteins must fold correctly to carry out their biological functions. Misfolded proteins can lead to diseases such as Alzheimer's and Parkinson's.
Protein expression: Cells regulate protein expression to control their function. Understanding the regulation of protein expression is essential in understanding many biological processes.
Enzymes: Proteins that catalyze chemical reactions in cells by lowering the activation energy required for the reaction to occur. Enzymes are essential for the proper functioning of cells and organisms.
Structural proteins: Proteins that provide support and shape to cells and tissues. Examples of structural proteins include collagen, keratin, and actin.
Transport proteins: Proteins that facilitate the movement of molecules and ions across cell membranes or within the bloodstream. Hemoglobin, which transports oxygen in the blood, is an example of a transport protein.
Storage proteins: Proteins that bind and store nutrients for later use. Casein, a protein found in milk, is an example of a storage protein.
Quote: "Proteins differ from one another primarily in their sequence of amino acids, which is dictated by the nucleotide sequence of their genes, and which usually results in protein folding into a specific 3D structure that determines its activity."
Quote: "A linear chain of amino acid residues is called a polypeptide. A protein contains at least one long polypeptide."
Quote: "Short polypeptides, containing less than 20–30 residues, are rarely considered to be proteins and are commonly called peptides."
Quote: "The individual amino acid residues are bonded together by peptide bonds and adjacent amino acid residues."
Quote: "The sequence of amino acid residues in a protein is defined by the sequence of a gene, which is encoded in the genetic code."
Quote: "Shortly after or even during synthesis, the residues in a protein are often chemically modified by post-translational modification."
Quote: "Some proteins have non-peptide groups attached, which can be called prosthetic groups or cofactors."
Quote: "Proteins can also work together to achieve a particular function, and they often associate to form stable protein complexes."
Quote: "Once formed, proteins only exist for a certain period and are then degraded and recycled by the cell's machinery through the process of protein turnover. A protein's lifespan is measured in terms of its half-life and covers a wide range."
Quote: "Like other biological macromolecules such as polysaccharides and nucleic acids, proteins are essential parts of organisms and participate in virtually every process within cells."
Quote: "Proteins also have structural or mechanical functions, such as actin and myosin in muscle and the proteins in the cytoskeleton, which form a system of scaffolding that maintains cell shape."
Quote: "Other proteins are important in cell signaling, immune responses, cell adhesion, and the cell cycle."
Quote: "In animals, proteins are needed in the diet to provide the essential amino acids that cannot be synthesized."
Quote: "Proteins may be purified from other cellular components using a variety of techniques such as ultracentrifugation, precipitation, electrophoresis, and chromatography."
Quote: "Methods commonly used to study protein structure and function include immunohistochemistry, site-directed mutagenesis, X-ray crystallography, nuclear magnetic resonance and mass spectrometry."