In biochemistry, ligands are substances that bind to biomolecules to form complexes for biological purposes. Ligands can be a single atom or ion, as well as larger and more complex molecules of natural or synthetic origin. In general, the binding between a ligand and target molecule is reversible by dissociation, while irreversible covalent binding is atypical in biological systems.
In multicellular organisms, cell adhesion, recognition and communication usually involve ligand-receptor interactions. Receptors can be divided into cell membrane receptors and intracellular receptors depending on their location. Intracellular receptors include nuclear receptors and cytoplasmic receptors such as enzymes, nucleic acids, and ribosomes. Cell membrane receptors are water-soluble, membrane-anchored, or membrane-embedded macromolecules with complex three-dimensional structures. Ligands bind to receptor proteins to alter the conformation of the receptors, which composes the functional state of the receptors. Ligands are substances of various nature, such as peptides, proteins, nucleic acids, steroids, and artificial compounds. The receptor and ligand form a complementary pair with non-covalent bonds formed by Van der Waals forces, hydrophobic, π-, ionic or electrostatic interactions. A cascade of chemical reactions occurs when receiving a signal resulted from the binding of a ligand to its complementary receptor. Ligand-receptor interactions play essential roles in physiological and pathological signaling. They initiate cell proliferation, apoptosis, motility, and other dynamic processes, as well as maintain cell homeostasis and the equilibrated functioning of all cell systems. Nuclear receptors are ligand-inducible transcription factors that specifically regulate the expression of target genes and thereby control a variety of physiological processes sun as development, inflammation, toxicology, reproduction, and metabolism. Nuclear receptor ligands include a wide range of chemicals, such as vitamin D, retinoids, bile acids, phospholipids, steroid hormones, and thyroid hormones. Binding of ligands to nuclear receptors causes conformational changes in nuclear receptors that alter the cellular location of the nuclear receptors and/or their interactions with cofactors, which ultimately translate into changes in gene expression. In addition, some ligands bind directly to nucleic acid molecules, and their interactions are fundamental to many intracellular processes. In DNA-ligand binding, ligands can be small molecules, ions, or proteins that bind to the DNA strands through different binding modes. In these small molecules, natural alkylating agents (e.g., mitomycin C) and synthetic agents (e.g., platinum compounds) cause DNA interstrand crosslinks, leading to disruption of DNA replication and transcription.
Amerigo Scientific offers a wide range of ligands targeting ion channels, transporters, nuclear receptors, DNA interstrand crosslinks, and multiple subfamilies of G-protein-coupled receptors (GCPRs). These GCPRs targeted by our ligand products include acetylcholine receptors, adenosine receptors, adrenergic receptors, cannabinoid and opioid receptors, chemokine receptors, dopamine receptors, serotonin receptors, histamine receptors, metabotropic glutamate receptors, peptide receptors, prostanoid receptors, purinergic receptors, smoothened receptors, etc.