Hydrophobic interactions nuclease

Lipoteichoic acids (from gram-positive bacteria) [56411-57-5J. Extracted by hot phenol/water from disrupted cells. Nucleic acids that were also extracted were removed by treatment with nucleases. Nucleic resistant acids, proteins, polysaccharides and teichoic acids were separated from lipoteichoic acids by anion-exchange chromatography on DEAE-Sephacel or by hydrophobic interaction on octyl-Sepharose [Fischer et al. Ear J Biochem 133 523 1983]. 

The changes in structure of denatured nuclease as a function of urea concentration (Fig. 3) suggest that, as hydrophobic interactions are weakened and the backbone becomes more highly solvated, the chain expands gradually. The data presented by Millet et al. in this volume suggest that this expansion does not continue asymptotically as predicted by simple polymer physical chemistry. This is the behavior expected for a polypeptide chain trapped in a small region of conformation space. Most, perhaps all, of the conformations accessible in the expanded denatured state may have a native-like topology. 

By increasing the hydrophobicity of plasmids and reducing their net negative surface charge, PVP may facilitate the uptake of plasmids by muscle cells. Intramuscular injection of PVP-based plasmid formulations in rats significantly increased the number and distribution of expressing cells, as compared to unformulated plasmid. The formation of condensed interpolyelectrolyte complexes between PVP and DNA has been proposed to both protect DNA from nuclease degradation and facilitate its cellular uptake by hydrophobic interaction with cell membranes. The increased hydrophobicity of the complex may enhance interaction with cell membranes and facilitate cell uptake. 

Hydrophobic interactions exerted by substituents at position 5 of cytosine or uracil enhance stability of DNA/RNA-hybrids (70,71) [163]. Derivatives with longer alkyl chains reduce duplex stability [169], with aminoalkyl residues being an exemption [170]. Above all, ethinyl substitution at position C5 of pyrimidine bases results in significantly increased binding affinity, as shown with binding of modified poly(rU) and poly(rA) [164]. Also, substitution with propinyl showed the same effect (73,74), which was attributed to ji-ji-interactions of the alkinyl substituent with the nucleobase in the 5 -neighbourhood. Oligomers of this type form duplexes with RNA, which can activate RNase-H. Since there is only a minor influence on nuclease resistance, such modifications are preferentially applied in combination... 

Cydoamyloses have been functionalized. For example, attached phosphoric acid groups catalyse the enolization of ketones and some catalyse the hydrolysis of acetals. Attached imidazole groups have been used as models for ribo-nuclease. Cydoamyloses functionalized with polyamines interact strongly with metal-ions and the resultant complex binds hydrophobic anions more strongly than the cydoamylose without metal-ion co-ordination. ... 

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