Physical Structure of Nucleoprotamines and Protamines

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 

This result was taken into consideration in the third model (Fig. IX-3), based on the data from small-angle X-ray diffraction and electron-microscope studies [Raukas et al, 1966 (1, 2)]. In this case four DNA-protamine molecules which are very similar to those in the first model are presumed to be bound by protamine and/or metal ions (such as Mg+- or Ca+). 

Recently the Japanese group investigated the interaction of clupeine or basic oligopeptides with DNA using techniques of melting profile (Inoue and Ando, 1966 Kawashima et al. 1969 see also Chap. X. C. 1), sedimentation [Inoue and Ando, 1970 (1)J, optical rotatory dispersion (Inoue and Ando, 1968, 1969), gel filtration (Inoue and Ando, 1969), and electron microscopy (Inoue and Fuke, 1970 see Fig. IX-4). On the basis of these results, they proposed a model as shown in Fig. IX-5 for reconstituted DNA-clupeine. 

The structure of nucleohistone appears to be rather different from that of nucleoprotamine, since its X-ray diffraction pattern is different (Wilkins and Zubay, 1959 Zubay and Wilkins, 1962 Pardon et al., 1967), also the position of the amide II band in the infrared absorption spectrum and the rate of deuteration [Bradbury etal., 1962 (2)j. 

The deuterium exchange reaction of protamine is very fast, less than 3 min being required for the complete deuteration of a film exposed to D2O vapour [Linder-str0M-Lang, 1956 Bradbury et al., 1962 (1)]. This indicates that protamine is not in a-helical configuration but in some extended form. Protamine has the amide I band at 1650 to 1660 cm and the amide II band at 1552 cm , which is characteristic 

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