Compstatin is a novel and potent 13-residue cyclic peptide acting as a potent inhibitor of the complement system C3 with species specificity. Compstatin binds to baboon C3 and is resistant to proteolytic cleavage in baboon blood (similar to humans).

Physicochemical Properties

Molecular Formula	C66H99N23O17S2
Molecular Weight	1550.7662
Exact Mass	1549.7
CAS #	206645-99-0
Related CAS #	Compstatin TFA
PubChem CID	25082538
Appearance	White to off-white solid powder
LogP	1.402
Hydrogen Bond Donor Count	22
Hydrogen Bond Acceptor Count	23
Rotatable Bond Count	25
Heavy Atom Count	108
Complexity	3180
Defined Atom Stereocenter Count	14
HS Tariff Code	2934.99.9001
Storage	Powder-20°C 3 years 4°C 2 years In solvent -80°C 6 months -20°C 1 month Note: Please store this product in a sealed and protected environment (e.g. under nitrogen), avoid exposure to moisture and light.
Shipping Condition	Room temperature (This product is stable at ambient temperature for a few days during ordinary shipping and time spent in Customs)

Biological Activity

ln Vitro	Comprestatin in human blood has an in vitro half-life of roughly two hours [2]. Comprestatin creates pearl clusters in solution when it rotates β on the Gln-5-Gly-8 residue with the disulfide bridge Cys-2-Cys12, residues Ile-1-Val-4 and Thr-13 [3].
ln Vivo	When compstatin (21 mg/kg) was administered as a combination bolus and infusion medication, total suppression was seen. Compstatin fully prevents heart rate, systemic, central, and pulmonary arterial pressure from being negatively impacted by heparin/protamine-induced complement activation in vivo [1]. In baboons smoking, paroxetine remains constant for almost twenty-four hours [1]. Pig xenografts in the comprestatin-infused group had a substantially longer transitory period than those in the saline group [2].
Animal Protocol	Animal/Disease Models: Juvenile baboons (P. Anubis) weigh 10.5-28.8 kg [1]. Doses: 50, 25 mg/kg, 60 minutes after heparin injection, 2 minutes before protamine injection. Route of Administration: Push Note. Experimental Results: Complete inhibition of complement activation induced by heparin-protamine complex.
References	[1]. Inhibition of heparin/protamine complex-induced complement activation by Compstatin in baboons. Clin Immunol. 2000 Sep;96(3):212-21. [2]. Compstatin, a peptide inhibitor of C3, prolongs survival of ex vivo perfused pig xenografts. Xenotransplantation. 1999 Feb;6(1):52-65. [3]. Structure of compstatin in complex with complement component C3c reveals a new mechanism of complement inhibition. J Biol Chem. 2007 Oct 5;282(40):29241-7. [4]. Inhibition of human complement by a C3-binding peptide isolated from a phage-displayed random peptide library. J Immunol. 1996 Jul 15;157(2):884-91.

Solubility Data

Solubility (In Vitro)	H2O : ~100 mg/mL (~64.48 mM)
Solubility (In Vivo)	Solubility in Formulation 1: 100 mg/mL (64.48 mM) in PBS (add these co-solvents sequentially from left to right, and one by one), clear solution; with sonication.  (Please use freshly prepared in vivo formulations for optimal results.)

Preparing Stock Solutions		1 mg	5 mg	10 mg
	1 mM	0.6448 mL	3.2242 mL	6.4484 mL
	5 mM	0.1290 mL	0.6448 mL	1.2897 mL
	10 mM	0.0645 mL	0.3224 mL	0.6448 mL

*Note: Please select an appropriate solvent for the preparation of stock solution based on your experiment needs. For most products, DMSO can be used for preparing stock solutions (e.g. 5 mM, 10 mM, or 20 mM concentration); some products with high aqueous solubility may be dissolved in water directly. Solubility information is available at the above Solubility Data section. Once the stock solution is prepared, aliquot it to routine usage volumes and store at -20°C or -80°C. Avoid repeated freeze and thaw cycles.