Protamine from salmon has been used to avoid in vitro AT complex formation in samples from dogs pre-treated with heparin. It has also been used to study the influences of external potential on adsorption of various proteins to a metal surface.
정의
protamine: Any of a group of proteinsof relatively low molecularweight found in association with thechromosomal DNA of vertebratesperm cells. They contain a singlepolypeptide chain comprising about67% arginine. Protamines are thoughtto protect and support the chromosomes.
일반 설명
Protamines are proteins rich in cysteine and arginine. It possesses many phosphorylation sites. Salmon fish contains around 15 genes encoding protamine. It is found to be localized to the sperm head.
Mechanism of action
Protamine sulfate has been approved in the United States as a specific antagonist to heparin since
1968. Protamines are an arginine-rich, highly basic group of simple proteins derived from
salmon sperm. The highly acidic heparin polysaccharides exhibit their anticoagulant activity through
binding to antithrombin III. Because of the basicity of protamine, heparin has an increased affinity
for protamine relative to antithrombin III. In fact, its binding affinity for protamine is so much greater
than that of antithrombin III that protamine actually will induce dissociation of the
heparin/antithrombin III complex. If protamine is administered in the absence of heparin, it can have
marked effects on coagulation. Protamine is not completely selective for heparin and, in vivo, also
interacts with fibrinogen, platelets, and other plasma proteins causing anticoagulation. For this
reason, use of the minimal amount of protamine necessary to antagonize heparin-associated
bleeding should be employed (usually 1 mg of protamine intravenously for every 100 U of heparin
remaining in the patient).
부작용
Anaphylaxis also has been associated with the use of protamine. Although development of protamine
anaphylaxis is not limited to diabetics, those patients with diabetes that have used protaminecontaining insulin (NPH or protamine zinc) do have a slightly increased risk of anaphylaxis. Some less common reactions to protamine include pulmonary vasoconstriction, hypotension, and thrombus
formation.
