Cobalt hexamine

Wolberger etal., 1988 lOmM cobaltic hexamine, 1 mM MgCl2,36% (w/v) (NH4)2S04... 

High concentration, however, is not the only means to obtain LC phases of DNA in aqueous solutions. DNA has been found to collapse upon adding in the solutions various condensing agents, which introduce effective attractive interhelical interactions. This is what happens with alcohols and other solvents, which reduce DNA solubility [40], or with multivalent cations like spermidine, spermine, and cobalt hexamine, which are thought to establish correlated counterion fluctuations with... 

Early studies reported that in aqueous solutions at room temperature a cation of valence +3 or greater induces DNA condensation , e.g., natural polyamines such as spermidine3+ (Gosule and Schellman, 1976 Maiquet et al., 1987 Baeza et al., 1987, 1992 Conrad and Topal, 1989 Baeza et al., 1992 Sikorav el al., 1994 Fang and Hoh, 1998 Bottcher el al., 1998), spermine4+ (Chattoraj et al., 1978 Gosule and Schellman, 1978 Raspaud et al., 1998, 1999), metal cations such as cobalt hexamine (Co(NH3)3 6) (Widom and Baldwin, 1980, 1989 Schwinefus and Bloomfield, 2000), polylysine (Laemmli, 1975), polyethyleneimine... 

According to the recent study on DNA condensation with titration calorimetry, it was indicated that condensations are entropically driven both by cobalt hexamine and spermidine (Matulis et al., 2000). This result corresponds well to the temperature dependence on the bimodal distribution between coil and compact states obtained with single chain observation (Murayama and Yoshikawa, 1999). 

Widom, J. and Baldwin, R.L. (1983) Monomolecular condensation of DNA induced by cobalt hexamine. Biopolymers, 22, 1595-1620. 

In comparison to aqueous soap solutions there exist relatively few determinations of Krafft points in nonpolar surfactant solutions. An interesting example is due to Addison and Furmidge21 who determined the solubilities of four alkylpyri-dinium iodides (dodecyl-, tetradecyl-, hexadecyl-, and octadecyl-) in xylene (mixture of isomers, b.p. 138 °C). The solubilities were plotted against 1/T (see Fig. 22). The breaks in the curves and the chain length effect (which is much less pronounced compared to aqueous solutions) are clearly shown. Similar experiments have been reported by Mehrotra et al.146 on copper soaps in various organic solvents and by Malik et al.140 on cobalt hexamine soaps. 

Malik, W. U., Jain, K., Siddiqui, M. J. Solutions of cobalt hexamine soaps in organic solvents. In Proceedings Intern. Conf. Colloid and Surface Science. Vol. 1, p. 501, Wolfram,... 

Figure 24 Portion of a 500-MHz 2-D NOESY spectrum in 90% H20/10% D2O, 10 °C, of the hairpin rihozyme B domain in the presence of 1 mM cobalt hexamine, which resonates at 3.65 ppm. NOEs could he unambiguously assigned to the imino protons of nucleotides G2, U3, and G4 (a) and the amino protons of C35 and C37 and the H8 protons of G2 and G7 (h). NOEs with imino (a) and amino (b) protons are shown. (Adapted from Butcher, Allain and Feigon. 2000 American Chemical Society)...

Figure 8.18 Schematic view of the structure of the cobalt hexamine complex.

Gene delivery vehicles The DNA chain is collapsed into a compact globule through neutralization of its negative charge by cationic polymers such as polyamines and multivalent cations such as spermidine and cobalt hexamine... 

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