Definition of protamine in US English:



  • Any of a group of simple proteins found combined with nucleic acids, especially in fish sperm.

    • ‘If insulin were combined with protamine it would prolong the period of absorption of the hormone.’
    • ‘Some of the unique human protamines are found in human fetal brain tissue and the adult human medulla, indicating that their function may not be specific to sperm.’
    • ‘From recent developments in molecular biology, it is becoming clear that cationic chemical species, such as histone octamer, protamine, spermidine, etc. play an essential role in the packing of long DNA chains into the nucleus.’
    • ‘During the process of spermatogenesis in animal species, protamines replace histones and bind sperm DNA.’
    • ‘Sperm chromatin contains protamines that must be replaced by histones before undergoing condensation.’


Late 19th century: from proto- ‘original’ + amine.