Protamine

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protamine

[′prōd·ə‚mēn]
(biochemistry)
Any of the simple proteins that are combined with nucleic acid in the sperm of certain fish, and that upon hydrolysis yield basic amino acids; used in medicine to control hemorrhage, and in the preparation of an insulin form to control diabetes.

Protamine

 

a protein of low molecular weight that occurs in the nuclei of spermatozoa in fish and birds. Its molecular weight ranges from 4,000 to 12,000.

The basic properties of protamines are determined by their characteristically high content of basic amino acids, especially arginine (70–80 percent). Protamines are readily soluble in water and in acid and neutral media. They are precipitated by alkalies and do not denature when heated. The protamines that have been studied are mainly those found in mature fish spermatozoa, where they constitute a fraction of the basic protein but nearly the entire nuclear protein. The amino-acid composition of protamines is specific for each species of fish.

In cell nuclei, protamines, like histones, are associated with deoxyribonucleic acids to form nucleoprotamines. X-ray diffraction analysis has shown that the protamine chain is the third strand coiled around the DNA double helix. Protamines form salts in the presence of acids and complexes with acid proteins; in medicine, the slightly soluble complex of protamine and insulin is used to prolong the effectiveness of the latter.

References in periodicals archive ?
Histona bagh kromatini, protamine bagli kromatinden ayirmak icin micrococcal ntikleaz sindirimi ve jel purifikasyon yontemi kullanmislardir.
The aetiology of sperm protamine abnormalities and their potential impact on the sperm epi-genome.
Protamine 1: protamine 2 stoichiometry in the sperm of eutherian mammals.
A modified protocol of the Sakaguchi histochemical reaction for arginine (Barka & Anderson 1965) was used to assess alteration of histone proteins to arginine-rich protamines during spermiogenesis in lycosid spiders.
During spermatogenesis and epididymal transit, nuclear histones are replaced by arginine/cysteine rich protamines (10).
During chromatin packaging endogenous nucleases (topoisomearse II) are activated to create and ligate nicks that facilitate replacement of histones with protamines during spermatogenesis by relieving torsional stress (15).