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This reference table compiles molecular weight data for over 50 common therapeutic and research peptides. Molecular weight is expressed in Daltons (Da) and is calculated as the sum of amino acid residue masses minus water molecules lost during peptide bond formation. Modifications (acylation, PEGylation, cyclization) are noted where applicable.

Hormones and Metabolic Peptides

Section titled “Hormones and Metabolic Peptides”
PeptideSequence LengthMW (Da)FormulaHalf-LifeTherapeutic Class
Insulin (human)51 aa5808C₂₅₇H₃₈₃N₆₅O₇₇S₆4–6 min (IV)Antidiabetic
Insulin lispro51 aa5808C₂₅₇H₃₈₃N₆₅O₇₇S₆3–5 hrsRapid-acting insulin
Insulin aspart51 aa5808C₂₅₇H₃₈₃N₆₅O₇₇S₆3–5 hrsRapid-acting insulin
Insulin glargine51 aa6063C₂₆₇H₄₀₄N₆₄O₇₈S₆12–16 hrsLong-acting insulin
Insulin degludec51 aa6108C₂₆₉H₄₁₀N₆₄O₇₈S₆>42 hrsUltra-long insulin
GLP-1(7-36)30 aa3298C₁₄₉H₂₂₂N₄₀O₄₃2–5 minIncretin
Exenatide39 aa4186C₁₈₅H₂₈₄N₅₀O₆₀2–4 hrsGLP-1 RA
Liraglutide31 aa3751C₁₇₂H₂₆₅N₄₃O₅₁13 hrsGLP-1 RA
Semaglutide31 aa4114C₁₈₇H₂₉₁N₄₅O₅₉165 hrsGLP-1 RA
Dulaglutide31 aa~63,000Fc fusion96 hrsGLP-1 RA
Tirzepatide39 aa4810C₂₂₅H₃₄₇N₅₁O₆₉~5 daysGIP/GLP-1 dual RA
GIP(1-42)42 aa4984C₂₂₁H₃₄₀N₆₀O₆₈5–7 minIncretin
Amylin37 aa3901C₁₆₉H₂₆₇N₅₅O₅₇10–15 minAmylin analog
Pramlintide37 aa3949C₁₇₁H₂₆₉N₅₅O₅₉10–15 minAmylin analog

Growth Hormone axis

Section titled “Growth Hormone axis”
PeptideSequence LengthMW (Da)FormulaHalf-LifeTherapeutic Class
Growth hormone (hGH)191 aa22,125C₉₉₀H₁₅₂₈N₂₆₂O₂₉₅S₇15–20 minGH secretagogue
Sermorelin29 aa3358C₁₄₉H₂₄₇N₄₅O₄₂12–15 minGHRH analog
CJC-129530 aa3368C₁₅₂H₂₅₂N₄₄O₄₆6–8 hrsGHRH analog
CJC-1295 DAC30 aa~3600PEGylated6–8 daysGHRH analog
Ipamorelin5 aa712C₃₈H₄₉N₉O₅2 hrsGH secretagogue
GHRP-66 aa874C₄₆H₅₆N₁₂O₉15–20 minGH secretagogue
GHRP-26 aa818C₄₅H₅₅N₉O₉15–20 minGH secretagogue
MK-677Non-peptide625C₂₇H₃₆N₄O₅S1–2 hrsGH secretagogue
Tesamorelin44 aa5177C₂₃₀H₃₅₃N₅₉O₆₅20–30 minGHRH analog

GnRH and Reproductive Peptides

Section titled “GnRH and Reproductive Peptides”
PeptideSequence LengthMW (Da)FormulaHalf-LifeTherapeutic Class
GnRH10 aa1182C₅₅H₇₅N₁₇O₁₃2–4 minGonadotropin-releasing
Leuprolide9 aa1209C₅₉H₈₄N₁₆O₁₂3–4 hrsGnRH agonist
Triptorelin10 aa1312C₆₄H₈₂N₁₈O₁₃3–5 hrsGnRH agonist
Goserelin10 aa1269C₅₉H₈₄N₁₈O₁₄2–4 hrsGnRH agonist
Buserelin9 aa1239C₆₀H₈₆N₁₆O₁₃80 minGnRH agonist

Oxytocin and Vasopressin

Section titled “Oxytocin and Vasopressin”
PeptideSequence LengthMW (Da)FormulaHalf-LifeTherapeutic Class
Oxytocin9 aa1007C₄₃H₆₆N₁₂O₁₂S₂3–5 min (IV)Uterotonic
Vasopressin (AVP)9 aa1084C₄₆H₆₅N₁₅O₁₂S₂10–20 minAntidiuretic
Desmopressin9 aa1069C₄₆H₆₄N₁₄O₁₂S₂1–2 hrsAntidiuretic
Carbetocin9 aa994Modified oxytocin12–33 hrsUterotonic
Atosiban9 aa994Oxytocin antagonist12 minTocolytic

Somatostatin Analogs

Section titled “Somatostatin Analogs”
PeptideSequence LengthMW (Da)FormulaHalf-LifeTherapeutic Class
Somatostatin14 aa1638C₇₆H₁₀₄N₁₈O₁₉S₂1–3 minHormone inhibitor
Octreotide8 aa1019C₄₉H₆₆N₁₀O₁₀S₂1.5–2 hrsSomatostatin analog
Lanreotide8 aa1096C₅₄H₆₉N₁₁O₁₀S₂23–30 daysSomatostatin analog
Pasireotide14 aa1695C₇₆H₁₀₅N₁₈O₂₀S₂12–16 hrsSomatostatin analog

Tissue Repair Peptides

Section titled “Tissue Repair Peptides”
PeptideSequence LengthMW (Da)FormulaHalf-LifeTherapeutic Class
BPC-15715 aa1419C₆₂H₉₈N₁₆O₂₂Hours (est.)Cytoprotective
Thymosin β443 aa4921C₂₁₂H₃₅₀N₅₆O₇₈S2–4 hrsActin regulator
GHK-Cu3 aa340C₁₄H₂₄N₆O₄ + Cu1–2 hrsCopper peptide
Thymosin α128 aa3108C₁₂₉H₂₁₅N₃₃O₅₅2 hrsImmunomodulator

Melanocortin Peptides

Section titled “Melanocortin Peptides”
PeptideSequence LengthMW (Da)FormulaHalf-LifeTherapeutic Class
α-MSH13 aa1646C₇₇H₁₀₉N₂₁O₁₉S1–3 minMelanocortin agonist
Melanotan I13 aa1646C₇₇H₁₀₉N₂₁O₁₉S1 hrMelanocortin agonist
Melanotan II7 aa1024C₅₀H₆₉N₁₅O₉1–3 hrsMelanocortin agonist
Afamelanotide13 aa1646C₇₇H₁₀₉N₂₁O₁₉S~1 hrMC1R agonist
PT-141 (Bremelanotide)7 aa1024C₅₀H₆₈N₁₄O₁₀2.7 hrsMC4R agonist

Antimicrobial Peptides

Section titled “Antimicrobial Peptides”
PeptideSequence LengthMW (Da)FormulaHalf-LifeTherapeutic Class
Melittin26 aa2847C₁₃₁H₂₂₉N₃₉O₃₁MinutesAntimicrobial
Defensin (α)29–35 aa3000–4000Disulfide-richVariableAntimicrobial
LL-3737 aa4493C₂₀₅H₃₄₀N₆₀O₅₃1–2 hrsAntimicrobial

Other Therapeutic Peptides

Section titled “Other Therapeutic Peptides”
PeptideSequence LengthMW (Da)FormulaHalf-LifeTherapeutic Class
Teriparatide (PTH 1-34)34 aa4118C₁₈₁H₂₉₁N₅₅O₅₁S₂4–8 minBone formation
Calcitonin (salmon)32 aa3432C₁₄₅H₂₄₀N₄₄O₄₈S₂10 minBone resorption
Eptifibatide7 aa832C₃₅H₄₉N₁₁O₉S₂1.5–2.5 hrsAntiplatelet
Bivalirudin20 aa2180C₉₈H₁₃₈N₂₄O₃₇25 minAnticoagulant
Nesiritide32 aa3464BNP analog18 minHeart failure

Molecular Weight Distribution

Section titled “Molecular Weight Distribution”
MW Range (Da)Peptide CountClassOral Bioavailability
<10008Short peptides, GH secretagoguesVariable (10–70%)
1000–500030Medium peptides<5% (typical)
5000–10,0008Large peptides, insulin analogs<1%
10,000–50,0005Protein therapeutics<0.1%
>50,0002Fc fusion proteins<0.1%

Molecular Weight Calculation

Section titled “Molecular Weight Calculation”

The molecular weight of a linear peptide is calculated as:

MW = Σ MW(residues) − (n − 1) × 18.015

Where:

  • Σ MW(residues) = sum of amino acid residue molecular weights
  • n = number of residues
  • 18.015 Da = mass of water lost per peptide bond (condensation reaction)

For disulfide-bonded peptides, subtract 2.016 Da per disulfide bond (loss of 2 hydrogen atoms).

Section titled “Related Pages”