CALM Peptides

    Peptide Research Glossary: A–Z

    A comprehensive reference of terminology used in peptide research. Each definition links to relevant deep-dive articles and product pages for further reading.

    A
    ACTH (Adrenocorticotropic Hormone)
    A 39-amino acid peptide hormone produced by the anterior pituitary gland that stimulates cortisol production from the adrenal cortex. Semax is derived from the ACTH(4-10) fragment.
    Alpha-MSH (Alpha-Melanocyte-Stimulating Hormone)
    A 13-amino acid neuropeptide derived from proopiomelanocortin (POMC) that acts on melanocortin receptors. Melanotan II and PT-141 are synthetic analogs of alpha-MSH.
    Amino Acid
    The building blocks of peptides and proteins. There are 20 standard amino acids, each with a unique side chain (R group) that determines its chemical properties. Amino acids are linked by peptide bonds.
    AMPK (5' AMP-Activated Protein Kinase)
    A central metabolic regulator enzyme often called the cell's "fuel gauge." Activated by MOTS-c and involved in glucose uptake, fatty acid oxidation, and metabolic homeostasis.
    Amphipathic
    Having both hydrophilic (water-loving) and hydrophobic (water-repelling) regions. LL-37 adopts an amphipathic alpha-helical structure that enables its interaction with microbial membranes.
    Angiogenesis
    The formation of new blood vessels from pre-existing vasculature. Studied in the context of BPC-157 (via VEGF upregulation) and TB-500 (via endothelial cell migration).
    B
    BDNF (Brain-Derived Neurotrophic Factor)
    A key neurotrophin that supports neuronal survival, synaptic plasticity, and memory formation. Upregulated by Semax and Selank in preclinical models.
    Bioregulatory Peptide
    A class of short synthetic peptides (2–4 amino acids) studied for their proposed ability to interact with DNA and modulate gene expression. Examples include Epitalon, Thymalin, and Pinealon. See: What Are Bioregulatory Peptides?
    C
    Cardiolipin
    A phospholipid found exclusively in the inner mitochondrial membrane. Plays a critical role in electron transport chain organization. The primary binding target of SS-31.
    Cathelicidin
    A family of host defense proteins. LL-37 is the only human cathelicidin-derived antimicrobial peptide, cleaved from the precursor protein hCAP18.
    Certificate of Analysis (COA)
    A quality document reporting analytical test results for a specific production batch of a research compound. Includes HPLC purity data and mass spectrometry identity confirmation. See: Understanding COAs and Quality.
    Copper Peptide
    A peptide that forms a complex with copper ions. GHK-Cu is the most studied copper peptide complex, formed between the tripeptide Gly-His-Lys and copper(II) ions.
    Cyclic Peptide
    A peptide in which the amino acid chain forms a ring structure, typically through a lactam bridge. Melanotan II and PT-141 are cyclic heptapeptides.
    D
    D-Amino Acid
    The mirror image (enantiomer) of the standard L-amino acid. D-amino acids resist enzymatic degradation by most proteases. Used in FOXO4-DRI (D-Retro-Inverso modification) and SS-31 (D-Arg).
    D-Retro-Inverso (DRI)
    A peptide modification where the sequence is reversed and all L-amino acids are replaced with D-enantiomers. Maintains similar side-chain topology while gaining protease resistance. See: FOXO4-DRI.
    Deamidation
    A chemical degradation reaction where asparagine (Asn) or glutamine (Gln) residues convert to aspartate or glutamate. A common degradation pathway in stored peptides. See: Peptide Storage.
    Delta Wave Sleep
    The deepest phase of non-REM sleep (Stage 3), characterized by high-amplitude, low-frequency EEG waves. Associated with DSIP research.
    DPP-IV (Dipeptidyl Peptidase-IV)
    An enzyme that cleaves peptides at the N-terminus. Native GHRH is rapidly degraded by DPP-IV. CJC-1295 is engineered to resist DPP-IV cleavage.
    E
    E-E-A-T (Experience, Expertise, Authoritativeness, Trustworthiness)
    Google's quality assessment framework used to evaluate content reliability, particularly for health-adjacent topics.
    Electron Transport Chain (ETC)
    The series of protein complexes in the inner mitochondrial membrane that transfers electrons and generates ATP. SS-31 stabilizes ETC organization via cardiolipin interaction.
    Eumelanin
    Brown/black pigment produced by melanocytes. Provides greater UV protection than pheomelanin. Melanotan II shifts melanin production toward eumelanin via MC1R activation.
    F
    FAK (Focal Adhesion Kinase)
    A tyrosine kinase involved in cell adhesion and migration signaling. BPC-157 has been observed to activate the FAK-paxillin pathway in preclinical models.
    FOXO4
    Forkhead box O4 transcription factor. In senescent cells, FOXO4 sequesters p53 to prevent apoptosis. FOXO4-DRI is designed to disrupt this interaction.
    G
    G-Actin
    Globular (monomeric) actin, the soluble form that polymerizes into F-actin filaments. TB-500 (Thymosin Beta-4) sequesters G-actin in a 1:1 complex to regulate cytoskeletal dynamics.
    GHRH (Growth Hormone-Releasing Hormone)
    A hypothalamic peptide that stimulates GH release from pituitary somatotrophs. CJC-1295 and Tesamorelin are synthetic GHRH analogs.
    GHS-R (Growth Hormone Secretagogue Receptor)
    Also known as the ghrelin receptor (GHS-R1a). A GPCR on pituitary somatotrophs that, when activated, stimulates GH release. Ipamorelin is a selective GHS-R agonist.
    Glycosaminoglycan (GAG)
    Long unbranched polysaccharides in the extracellular matrix. GHK-Cu stimulates GAG deposition in fibroblast cultures.
    H
    Hayflick Limit
    The maximum number of times a normal somatic cell can divide before entering senescence (~50–70 divisions for human cells). Epitalon has been observed to extend cell division beyond this limit via telomerase activation.
    HPLC (High-Performance Liquid Chromatography)
    The gold standard analytical technique for determining peptide purity. Separates mixture components by differential interaction with a stationary phase. See: What Is HPLC Testing?
    I
    IGF-1 (Insulin-like Growth Factor 1)
    A hormone structurally similar to insulin, produced primarily in the liver in response to GH stimulation. Mediates many effects of the GH/IGF-1 axis.
    L
    Lactam Bridge
    A cyclic amide bond that forms a ring within a peptide, creating a cyclic structure. Present in Melanotan II and PT-141.
    Lyophilization
    Freeze-drying. The process of freezing a peptide solution and removing water under vacuum. Lyophilized peptides have superior stability compared to solutions. See: Peptide Storage.
    M
    Mass Spectrometry (MS)
    An analytical technique that measures the molecular weight of compounds. Used alongside HPLC to confirm peptide identity on a Certificate of Analysis.
    MC1R–MC5R
    The five melanocortin receptor subtypes. MC1R (pigmentation), MC3R (energy homeostasis, immune), MC4R (energy homeostasis, autonomic), MC5R (exocrine). Melanotan II is non-selective; PT-141 is MC4R/MC3R-preferring.
    Melanocortin
    A family of peptide hormones derived from POMC, including ACTH, α-MSH, β-MSH, and γ-MSH. The melanocortin system regulates pigmentation, energy balance, and immune function.
    Melanogenesis
    The biological process of melanin production in melanocytes. See: Melanotan II.
    Mitochondrial-Derived Peptide (MDP)
    A signaling peptide encoded by small open reading frames within the mitochondrial genome. MOTS-c was the first identified MDP.
    N
    NAD+ (Nicotinamide Adenine Dinucleotide)
    An essential coenzyme in all living cells, functioning as an electron carrier and sirtuin substrate. See: NAD+ deep-dive.
    Nootropic
    A compound studied for potential cognitive-enhancing effects. Semax and Selank are investigated as nootropic peptides in preclinical research.
    P
    Pentadecapeptide
    A peptide consisting of 15 amino acids. BPC-157 is a pentadecapeptide.
    Peptide Bond
    The covalent bond (−CO−NH−) linking amino acids in peptides and proteins. See: What Is a Peptide Bond?
    Pheomelanin
    Red/yellow melanin pigment. Provides less photoprotection than eumelanin.
    POMC (Proopiomelanocortin)
    A precursor protein processed into multiple bioactive peptides including ACTH, α-MSH, β-endorphin, and others.
    Protease
    An enzyme that catalyzes the hydrolysis of peptide bonds. Different protease families (serine, cysteine, metallo, aspartyl) use different catalytic mechanisms. Protease resistance is a key goal in peptide modification.
    R
    Reverse-Phase HPLC (RP-HPLC)
    The most common HPLC mode for peptide analysis, using a nonpolar stationary phase (C18) and polar mobile phase. Components separate by hydrophobicity. See: HPLC Testing.
    S
    SASP (Senescence-Associated Secretory Phenotype)
    The pro-inflammatory cocktail secreted by senescent cells, including cytokines, chemokines, and proteases. Targeted indirectly by FOXO4-DRI senolytic research.
    Senescence (Cellular)
    A state in which cells permanently exit the cell cycle but remain metabolically active. Accumulation of senescent cells is associated with aging. See: FOXO4-DRI.
    Senolytic
    A compound that selectively eliminates senescent cells while sparing healthy cells. FOXO4-DRI is a peptide-based senolytic research compound.
    Sirtuin
    A family of NAD+-dependent deacetylase enzymes (SIRT1–7) involved in DNA repair, metabolism, and stress responses. Sirtuin activity depends on NAD+ availability.
    Solid-Phase Peptide Synthesis (SPPS)
    The standard method for manufacturing synthetic peptides, involving stepwise addition of amino acids to a resin-bound growing chain. The method's efficiency affects final peptide purity.
    Somatotroph
    A cell type in the anterior pituitary gland that produces and secretes growth hormone. The target cell for both GHRH analogs and GHS-R agonists.
    T
    Telomerase
    A ribonucleoprotein enzyme that maintains telomere length by adding repetitive nucleotide sequences to chromosome ends. Activated by Epitalon in preclinical cell culture studies.
    Telomere
    Repetitive nucleotide sequences (TTAGGG in humans) at the ends of chromosomes that protect against degradation. Telomeres shorten with each cell division and are a hallmark of aging.
    Thymus
    The primary organ responsible for T-lymphocyte maturation. Source of Thymosin Alpha-1 and Thymalin. Undergoes age-related involution.
    TLR (Toll-Like Receptor)
    Pattern recognition receptors on innate immune cells. Thymosin Alpha-1 activates TLR2 and TLR9 to stimulate dendritic cell maturation.
    Tuftsin
    A naturally occurring tetrapeptide (Thr-Lys-Pro-Arg) derived from IgG that stimulates phagocytic activity. The core sequence of Selank.
    V
    VEGF (Vascular Endothelial Growth Factor)
    A signaling protein that promotes angiogenesis. Upregulated by BPC-157 and GHK-Cu in preclinical models.

    Disclaimer: All products referenced are sold for research and laboratory use only. Not for human consumption. These definitions are provided for educational purposes and do not constitute medical advice. CALM Peptides makes no claims that any product treats, cures, prevents, or diagnoses any disease.