protamina

Protamine, also known in some languages as protamina, is a small, highly basic nuclear protein that binds to DNA. It is rich in arginine and serves to neutralize the phosphate backbone of DNA, enabling tight condensation of chromatin in sperm cells.

In mammals, protamines replace histones during spermatogenesis. Two main forms, protamine 1 and protamine 2, are produced in the testes. They form inter- and intra-molecular disulfide cross-links that stabilize highly condensed sperm chromatin. The amount and ratio of protamines relative to histones are important for normal sperm morphology and DNA integrity; abnormal protamine expression or an altered P1:P2 ratio have been linked with male infertility in humans.

Protamine is found in the spermatozoa of many animals, most notably fish such as salmon, from which protamine is often isolated for medical use.

Medical use: Protamine sulfate is used clinically to reverse the anticoagulant effect of heparin during surgical procedures or dialysis. When given, it binds heparin to form a stable complex, reducing bleeding risk. Protamine can cause hypersensitivity reactions, particularly in individuals with fish allergies or prior exposure.

Safety and availability: As a therapeutic, protamine is typically administered under medical supervision. It is sourced from animal tissues, chiefly fish milt, and its composition can vary by source, which can influence allergenicity and pharmacological properties.