Tx2-6 is a toxin found in the venom of the Brazilian wandering spider

Brazilian wandering spider

Phoneutria, commonly known as Brazilian wandering spiders, armed spiders , or banana spiders , are a genus of aggressive and highly venomous spiders found in tropical South and Central America...

, Phoneutria nigriventer (Keys). It is a peptide

Peptide

Peptides are short polymers of amino acid monomers linked by peptide bonds. They are distinguished from proteins on the basis of size, typically containing less than 50 monomer units. The shortest peptides are dipeptides, consisting of two amino acids joined by a single peptide bond...

 of 48 residues, molecular weight 5291.3. This peptide is cleaved from a longer precursor with a signal peptide

Signal peptide

A signal peptide is a short peptide chain that directs the transport of a protein.Signal peptides may also be called targeting signals, signal sequences, transit peptides, or localization signals....

 and a glutamine-rich propeptide. It can cause priapism

Priapism

Priapism is a potentially harmful and painful medical condition in which the erect penis or clitoris does not return to its flaccid state, despite the absence of both physical and psychological stimulation, within four hours. There are two types of priapism: low-flow and high-flow. Low-flow...

. Tests on rats indicate that the toxin causes nitric oxide

Nitric oxide

Nitric oxide, also known as nitrogen monoxide, is a diatomic molecule with chemical formula NO. It is a free radical and is an important intermediate in the chemical industry...

 release, and its effect on erection is blocked by the nitric oxide synthase

Nitric oxide synthase

Nitric oxide synthases are a family of enzymes that catalyze the production of nitric oxide from L-arginine. NO is an important cellular signaling molecule, having a vital role in many biological processes...

 inhibitor L-NAME. However, it fully restored erectile function in rats developing hypertension

Hypertension

Hypertension or high blood pressure is a cardiac chronic medical condition in which the systemic arterial blood pressure is elevated. What that means is that the heart is having to work harder than it should to pump the blood around the body. Blood pressure involves two measurements, systolic and...

 due to injection of deoxycorticosterone

Deoxycorticosterone

11-Deoxycorticosterone is a steroid hormone produced by the adrenal gland that possesses mineralocorticoid activity and acts as a precursor to aldosterone. As its names indicate, it can be understood as 21-hydroxy- variant of progesterone or a 11-deoxy- variant of corticosterone...

 acetate. A study is underway at the Medical College of Georgia

Medical College of Georgia

Georgia Health Sciences University formerly known as, and now home of the, Medical College of Georgia , is a public academic health center, with its main campus located in the Medical District of Augusta, Georgia. It is the smallest of four research universities in the University System of Georgia...

 looking at possible uses for the chemical in erectile dysfunction

Erectile dysfunction

Erectile dysfunction is sexual dysfunction characterized by the inability to develop or maintain an erection of the penis during sexual performance....

medication.

External links

• Spider venom for Erectile Dysfunction (27 September 2009)