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 ?
Protamine 1: protamine 2 stoichiometry in the sperm of eutherian mammals.
Altered protamine expression and diminished spermatogenesis: what is the link'?
Altered protamine 2 expression is uncommon in donors of known fertility, but common among men with poor fert i I izing capacity, andmay reflect other abnormalities of spermi-ogenesis.
Sperm protamine 1/protamine 2 ratios are related to in vitro fertilization pregnancy rates and predictive of fertilization ability.
Thus, while P2 contains an unusually high lysine content compared to other protamines (20.
This led to the retroviral evolutionary hypothesis for the origin of protamines through a mechanism of horizontal transmission (infection) that would account for the sporadic distribution of protamines that was observed within different organisms of distantly related phylogenetic groups (Jankowski et al.
The increase in arginine content observed in PL SNBPs was likely driven by a transitional improvement of the interaction of SNBPs with DNA that, in the absence of a transcriptional activity, is better achieved by arginine-rich protamines.
Protamine 2 precursors, protamine 1/protamine 2 ratio, DNA integrity and other sperm parameters in infertile patients.
Dynamics of protamine 1 binding to single DNA molecules.
Further sensitivity to subtle changes in DNA is gained by incubation of the cells in the presence of Proteinase K, which removes protamines that otherwise impede DNA migration through the agarose.
During chromatin packing 85 per cent of the histones are replaced by protamine while the residual histones act as marker of genes which are expressed in early embryonic development.
DNA and total protamine masses in individual sperm from fertile mammalian subjects.