The amino acid sequence of human sperm protamine P1

Human sperm protamines have been extracted from spermatozoa pooled from several donors, converted to their S-pyridylethylated derivatives and resolved into two major components, P1 and PI, by Bio-Rex 70 chromatography. Protamine P1 was further purified by Bio-Gel P-10 chromatography and sequenced directly on a gas phase protein sequencer for 43 residues. To complete the sequence, P1 was cleaved at methionine 36 and the C-terminal tetradecapeptide was purified by h.p.i.c , and sequenced completely. The 50 residue sequence is: 10 20 30 40 ARYRC CRSQS RSRYY RQRQR SRRRR RRSCQ TRRRA MRCCR 50 PRYRP RCRRH. This sequence has a calculated molecular weight of 6674 and is homologous with four other published mammalian protamine sequences.