Nucleoprotamines and Protamines

Nucleohistones are widely distributed in the somatic cell nuclei of animals, while nucleoprotamines are limited to the mature sperm cell nuclei of certain families of fish. Protamines have been separated from sperm nuclei of more than 50 species of fish and are usually named after the family of fish, according to the proposal of Kossel [1896 (1, 2)]. The main protamines are summarized in Table II-l together with the genus and species names of the organisms from which they are derived. It may sometimes be necessary to re-examine the protamines listed in the table to confirm whether they are true protamines from completely mature sperm nuclei or whether they are from immature ones, which contain basic proteins of various other types, as described below. 

No protamine has ever been found in animal tissues other than sperm. Although the presence of protamines has also been reported in a snail (Helix aspersa) [Bloch and Hew, 1960 (1, 2)] and in lycopod pollen (Lycopodium clavatum) (D Alcontres, 1955), these results must be subjected to careful re-examination. 

Basic proteins of the histone type, or of a type intermediate between histone and protamine, are usually found in various amounts in cell nuclei of immature fish testes, often together with a protamine. Similar basic proteins of the histone type, but not protamines, are reported to be present in mature sperm cell nuclei of several fish and marine animals such as codfish (Stedman and Stedman, 1951), halibut, shad, sea urchin (Arbacia lixula and Stronglocentrotus lividus) starfish (Astropecten auran-tiacus and Echinaster spositus) (Kossel and Staudt, 1926), octopus (Eledone cirrosa) and some shellfish (Palau and Subirana, 1967). The same is true for some land animals such as Drosophila [Das et aL, 1964 (1,2,3)], grasshopper (Bloch and Brack, 1964 Das et al. 1965), and cricket (Kaye and McMaster-Kaye, 1966). No basic proteins can be readily extracted from mammalian sperm nuclei by acids (Dallam and Thomas, 1953). Nevertheless, there appears to exist in mammalian semen a basic keratin-like protein containing cystine in combination with DNA in a molecular ratio 

Family Origin Name of protamine Classi- fication Discovered by 

Clupetdae Clupea harengus (Norwegian Sea herring) Clupeine MP Kossel, 1897 Kossel and Dakin, 1904 

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Distribution of Nucleoprotamines and Protamines Table II-l. Origins, Classification, and Discoverers of Main Protamines... 

The Starting material used for preparing both nucleoprotamines and protamines is sperm heads or testis chromatin of fish obtained from freshly collected mature milts or sperm freshly drawn from mature testes. These mature milts or sperm contain essentially only one type of cell, spermatozoa, although the former often contain immature sperm cells and connective tissues which must be removed. Ways of preparing sperm heads, chromatin, nucleoprotamines, and protamines will be briefly reviewed in this chapter ... 

Fish sperm contain nucleoprotamines. Upon treatment with sulfuric acid, the nucleoprotamines are reduced to nucleic acid and protamine sulfate. The chemically heterogeneous protamines of molar mass 2000-8000 thus obtained contain only a few different kinds of amino acid residues per molecule. They are relatively rich in basic amino acids, as the composition of the protamines clupeine and salmine shows (Table 29-6), and never contain cystine, aspartic acid, or tryptophan. The basic amino acids are responsible for the bonding of the protein to the nucleic acid component. 

Nucleoprotamine dissolves in aqueous solution of NaCl (1—2 M) or ammonium sulfate to give a viscous solution. In such solutions it largely dissociates into DNA and protamine, but upon dilution (e.g., to 0.14 M NaCl) they combine to form white fibrous precipitates [Watanabe and Suzuki, 1951 (3)]. 

At the terminal stage of spermatogenesis of salmon fish, nucleohistones are replaced by nucleoprotamine. Not much is known about the mechanisms by which one kind of basic polypeptide is replaced by another. What seems certain is that protamines are made in the cytoplasm and transferred to the nucleus before the displacement can take place. Prior to the exchange, both types of basic proteins, preformed histones and newly synthesized protamines, are phosphorylated. 

Within the scope of this book, the authors can describe only some of the features of protamines and nucleoprotamines. They would like to recommend the following reviews or books for further reading on protamines, histones, and nucleoproteins. 

Felix, K., Fischer, H., Krekels, A. Protamines and nucleoprotamines. Progr. Biophys. Biophys. Chem. 6, 1—23 (1956). 

Felix, K. Protamine, Nucleoprotamine und Gene (Translated into Japanese by T. Ando and K. Iwai). In Chemistry of proteins (Akabori, S., Mizushima, S., Eds.), Vol. V, 265—277. Tokyo Kyoritsu Shuppan Co. 1957. 

Separation and Purification of Protamines from Sperm Heads or Nucleoprotamine 11... 

In this section the development of the procedures to separate and purify protamine from sperm heads or nucleoprotamine, prepared as described in the preceding sections, will be reviewed historically according to the principle of the procedures. 

The second model of nucleoprotamine, proposed by Luzzati and Nicolaieff (1963) and Luzzati (1963), consists of hexagonally arranged DNA molecules with protamine and water filling up the gaps, so that it has the structure of an infinite... 

Fig. IX-2. A nucleoprotamine model (shown in section perpendicular to the rod direction) consisting of two-dimensional hexagonal array of DNA molecules, with protamine and water molecules filling up the gaps (from Luzzati and Nicolaieff, 1963)...

Fig. IX-5. Schematic models of DNA-clupeine complexes based on the thermal denatura-tion, optical rotatory dispersion, gel-filtration, and electron microscope studies. Primary complex clupeine molecules wind around the small grooves on the DNA double helix. Secondary complex the primary complexes are joined together in places by protamine bridges. Network a network of nucleoprotamine complexes as can be seen in the electron micrograph (cf. Fig. IX-4) (from Inoue and Ando, 1969)...

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