Polylysine, conformation

Bussiek, M., Mficke, N., and Langowski, J. (2003) Polylysine-coated mica can be used to observe systematic changes in the supercoiled DNA conformation by scanning force microscopy in solution. Nucleic Acids Res. 31, 137. 

Aleksina et al. investigating polymerization of methacrylic acid in the presence of poly-L-lysine found that the complex obtained by template polymerization has a 1 1 stoichiometry, while the same components obtained by separation of the complex and repeated mixing gave a complex in which the ratio of polylysine units to polyacid units is 2 3. The stable conformation of polylysine macromolecule in the complex obtained by template polymerization is the conformation of a-helix. 

The behaviour of copolymers SK is typical for the behaviour of copolymers with a hydrophobic polyvinyl block and a hydrophilic polypeptide block. They exhibit mesophases in water for water concentration ranging from 0 to 50% and the structure of the mesophases is lamellar23. The special feature of this lamellar structure consists in the conformation of the polylysine chains which are roughly to 15% in a 0-chain conformation, to 35% in an a-helix conformation and to 50% in a coiled conformation23, so that the hydrophilic block of such amphipatic copolymers has the same type of conformation as the hydrophilic part of the membrane proteins. 

The liquid phase synthesis on PEG has also been used for the conformational analysis of collagen-like sequences by CD studies 237). The attachment to PEG has also permitted the CD spectral delineation of the specific interactions between the polypeptide chains and sidechain groups 238,239). Thus, Anzinger et al. observed that onset of local ordered structures in the mesogenic side chains of polylysine blocks attached to PEG leads to significant, specific alteration in the backbone conformations of the peptide chain 239). 

The investigations presented focus on interpretation of polarization of fluorescence measurements and use of these measurements to study the structure of a representative spectrum of linear synthetic polypeptides, a vinyl polymer, and an intramolecularly cross-linked synthetic polypeptide. The methodological studies investigate the validity of the transition temperature as a structural parameter, the interaction of the fluorescent dye and the polymer to which it is conjugated, and the influence of the dye-polymer interaction on the measurements of various molecular parameters. The structural studies focus on the structure of the random coil, the helix-coil transition, the a-helix to conformation transition in polylysine, and the stability of the spatial structure in intramolecularly cross-linked synthetic polypeptides. 

Leckband D ef a/1993 Measurements of conformational changes during adhesion of lipid and protein (polylysine and S-layer) surfaces Biotech. Bloeng. 42 167-77... 

Circular dichroism spectra of polylysine in a-heli-cal (a), p-strand (P) and random coil (r) conformations. Adapted from N.J. Greenfield etal. Biochemistry (1967) 1630-1637 and 8 (1969) 4108-4116. 

Bystricky S, Malovlikova A, Sticzay T (1991) Interaction of acidic polysaccharides with polylysine enantiomers. Conformation probe in solution. Carbohyd Pol 15 299-308... 

Hydrolysis and protolysis have also been shown to be responsible for the absorption maxima observed in the alkaline range with proteins (9b) and polypeptides having a side chain amino group (10,18), and in the acid range with proteins. These maxima were first attributed to conformational equilibria (see paragraph 3). From the relaxation spectra for polylysine and polyornithine (10,18), koH values of about 10 9 s were obtained, i.e.,... 

The hydration dependence studies of the internal protein dynamics of hen egg white lysozyme by and H NMR relaxation have been presented. The relaxation times were quantitatively analysed by the well-established correlation function formalism and model-free approach. The obtained data was described by a model based on three types of motion having correlation times around 10 , 10 and 10 s. The slowest process was shown to originate from correlated conformational transitions between different energy minima. The intermediate process was attributed to librations within one energy minimum, and the fastest one was identified as a fast rotation of methyl protons around the symmetry axis of methyl groups. A comparison of the dynamic behaviour of lysozyme and polylysine obtained from a previous study revealed that in the dry state both biopolymers are rigid on both fast and slow time scales. Upon hydration, lysozyme and polylysine showed a considerable enhancement of the internal mobility. The side chain fragments of polylysine were more mobile than those of lysozyme, whereas the backbone of lysozyme was found to be more mobile than that of polylysine. 

A short presentation of the electrostatic interactions of acidic polysaccharides with d- and L-enantiomers of polylysine is given. As polysaccharide components pectate and alginates rich in l-guluronate and D-mannuronate, respectively were used. The results of the study by means of circular dichroism showed that the complex formation is governed by the stoichiometric ratio of the charges of both interacting components. The conformation of polysaccharide used for complexation was proved to be the decisive factor influencing the interaction efficiency. 

It is known that L-guluronan in solid state adopts a strictly two-fold helical conformation [8,10]. The polysaccharide with such conformation is not able to interact with polylysine effectively due to incompatibility of charge densities. The inability of alginate rich in L-guluronate to interact with either poly(D-lysine) or poly(L-lysine) confirms that the structure of L-guluronan itself is also strongly rigid in water solution. This conclusion is supported by the last observed interaction with the cationic molecule rhutenium red [11]. 

From comparison of complexation efficiencies of acidic polysaccharides with polylysine enantiomers the sense of conformational freedom of polysaccharide may be deduced. Our experiments have clearly shown that D-mannuronan in solution tends to adopt a left-handed helical structure, while D-galacturonan may be characterized by conformational freedom in a right-handed sense. 

The interactions of poly(amino acid)s with liposomes have long been used as models for lipid-protein interactions. Basic polypeptides [e.g., poly(L-lysine), poly(L-ornithine)] form complexes with negatively charged liposomes such as phosphatidylserine [43] and undergo a conformational change from a random to an a-helical configuration [44]. Copolymers of lysine and phenylalanine show a behavior similar to that of pure polylysine in the presence of phosphatidylserine SUV but remain in the random coil configuration and alter the distribution of liposomes in vivo. 

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