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It could be shown that the c. d. spectra of basic poly-a-amino-acids (BPA) solubilized in reverse micelles of the system AOT/H2O/iso-octane depend not only on w0 and the basic side-chain but also on the concentration of the BPA. Moreover the purification procedure applied to the AOT seems to influence the conformation of the BPA in the reverse micelles remarkably. For discussing the effect of AOT reverse micelles on the conformation of the solubilized BPA one has to take the ratio r′ of AOT-molecules to the number of basic peptide residues and therefore the concentration of empty reverse micelles into consideration. [ABSTRACT FROM AUTHOR]

The aim of this work was to investigate the molecular weight of DNA-protamine aggregates in aqueous solution as a function of the [Arg]/[nucleotide] ratio and as a function of the molecular weight distribution of the DNA. In the case of the polydisperse DNA the ultracentrifuge and the UV-absorption measurement show an increasing molecular weight with increasing clupeine content from 2 × 106 of the DNA itself to 18 × 106 of the aggregates. On the other hand, the homodisperse DNA shows the parallel behavior, but the molecular weight of the aggregates is four times higher. The high molecular weight aggregates of both samples have a very broad molecular weight distribution according to the broad sedimentation boundary traces. These high molecular weight aggregates are supposed to form networks of DNA-protamine complexes. [ABSTRACT FROM AUTHOR]

The sedimentation behavior of reversed micelles (RM) of the system AOT/H2O/iso-octane was studied before and after solubilizing poly(L-lysine). In contrast to the Schlieren-pattern of the system AOT/H2O/iso-C8, those of aOT/H2O(Lys)n/iso-C8 show two Schlieren peaks. The slowly moving one corresponds to the "empty RM", the other — with a higher sedimentation rate — to the "filled RM". From the size of the area below these peaks, it follows that at a maximum ≈ 45% of the RM are filled with (Lys)n. Also, the diffusion patterns show an overlapping of the diffusion process of these two species. The results obtained by the moving boundary method can be confirmed by equilibrium sedimentation measurements. As a result of these studies, the number of (Lys)n, AOT, and H2O molecules in one RM can be determined. In any case, in the filled RM, only one (Lys)n molecule is solubilized. [ABSTRACT FROM AUTHOR]

Protamines are strong basic nucleoproteins containing approximately 70% L-arginine. In aqueous solution they usually exist as an extended coil as a consequence of the electrostatic repulsion of the positively charged guanidinium side-chain of arginine. Their conformation in the native complex with DNA is, as of yet, unnknown. However, it is suspected to at least partially be an α-helix, due to the electrostatic interactions with the phosphoric acid anions of the DNA and a low degree of hydration. For studying these influences, studies on the conformation of protamines in reverse micelles, e.g., of the system AOT/i-octane/H2O depending on the H2O/AOT-ratio (w0-value) by circular dichroism (CD)-spectroscopy should be useful. Indeed, at low w0-values, α-helix spectra have been obtained, as well as a remarcable dependence of the conformation of the protamines on w0. The component YI of clupein shows a significant difference in conformation against YII and Z. [ABSTRACT FROM AUTHOR]

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