title: Isolation and amino-acid sequence analysis of human sperm protamines P1 and P2. Occurrence of two forms of protamine P2.
abstract: The two protamines of human sperm cell nuclei, P1 and P2, were isolated in pure form after extraction with 6M guanidine/5% mercaptoethanol and alkylation with vinyl pyridine by reversed-phase high-performance liquid chromatography. The amino-acid sequence of protamine P1 was determined by analysing the intact protein and the fragments obtained by cyanogen bromide cleavage. Out of the 50 amino-acid residues 24 are arginines and 6 are cysteines. The sequence of protamine P2 was determined by analysing the intact protein and the fragments resulting from cleavage with endoproteinase Lys-C and thermolysin. Protamine P2 was found to occur in two forms which only differ in their N-terminal regions. The form P2' is three amino-acid residues longer at the N-terminus than the form P2''. Out of the 57 amino-acid residues in the longer form 27 are arginines and 5 are cysteines. Human protamine P1 is highly homologous with the protamines isolated from bull, boar, ram and mouse sperm cells, but human protamine P2 shows a novel type of structure, although also here the dominant amino acids are arginine and cysteine.
mesh_terms: D000595:Amino Acid Sequence; D002851:Chromatography, High Pressure Liquid; D003488:Cyanogen Bromide / Q000494:pharmacology; D010450:Endopeptidases / Q000378:metabolism; D006801:Humans; D008297:Male; D008666:Metalloendopeptidases; D011479:Protamines / Q000032:analysis* / Q000302:isolation & purification; D013094:Spermatozoa / Q000032:analysis*; D013820:Thermolysin / Q000378:metabolism
chemical_list: D011479:Protamines; D010450:Endopeptidases; D008666:Metalloendopeptidases; C039830:peptidyl-Lys metalloendopeptidase; D013820:Thermolysin; D003488:Cyanogen Bromide