Purification and characterization of nuclear basic proteins of human sperm

Highly purified nuclei were obtained from human sperm without protein loss through the use of CHAPS (3-[(3-cholamidopropyl)dimethylammonio]-1-propanesulfonate), a newly available detergent. The basic protein complement of these nuclei is highly heterogeneous and comprises histones (some of which are testis-specific), protamines and proteins of intermediate basicity and molecular size. The protamines belong to two different classes of protein. Microheterogeneity observed in some of these protamines originates from slight variations in their amino acid composition as well as from post-synthetic modifications. Two of these protamines previously considered as two different proteins are in fact the same protein with different degrees of phosphorylation. All these protamines and intermediate basic proteins are characterized by high amounts of arginine and cysteine. Three of the protamines and all five intermediate basic proteins are also histidine-rich.