Novel Absorption and Fluorescence Characteristics of <scp>l</scp>-Lysine

Homchaudhuri, Lopamudra; Swaminathan, Rajaram

doi:10.1246/cl.2001.844

Cited by 49 publications

(52 citation statements)

References 9 publications

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“…In addition, the resultant diphosphated Lys conformations suggest that phosphates orient in a manner (Figure 1E) that prevents multiple Lys side chains from getting closer than 7 Å to each other, which is the distance that poly-Lys can exhibit in a variety of natural proteins. 69 Unlike poly-Arg, where the phosphate conformations permit stacking between guanidinium groups and the complex is compact, poly-Lys would have to be distorted when interacting with multiple phosphates resulting in suboptimal packing of phospholipid headgroups. These results show that multiple guanidinium groups readily maintain and organize a diphosphate coordination over a variety of side chain separations including the small spacing characteristic of poly-Arg, while for poly-Lys the inefficient packing of diphosphated amine groups cannot do so without incurring a large energetic penalty.…”

Section: Resultsmentioning

confidence: 99%

Molecular Basis for Nanoscopic Membrane Curvature Generation from Quantum Mechanical Models and Synthetic Transporter Sequences

et al. 2012

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We investigate the physical origin of peptide-induced membrane curvature by contrasting differences between H-bonding interactions of prototypical cationic amino acids, arginine (Arg) and lysine (Lys), with phosphate groups of phospholipid heads using quantum mechanical (QM) calculations of a minimum model, and test the results via synthetic oxaorbornene-based transporter sequences without the geometric constraints of polypeptide backbones. QM calculations suggest that although individual Lys can in principle coordinate two phosphates, they are not able to do so at small inter-Lys distances without drastic energetic penalties. In contrast, Arg can coordinate two phosphates down to less than 5 Å, where guanidinium groups can stack ‘face to face’. In agreement with these observations, poly-Lys cannot generate the nanoscale positive curvature necessary for inducing negative Gaussian membrane curvature, in contrast to poly-Arg. Also consistent with QM calculations, polyguanidine-oxanorbornene homopolymers (PGONs) showed that curvature generation is exquisitely sensitive to the guanidinium group spacing when the phosphate groups are near close packing. Addition of phenyl or butyl hydrophobic groups into guanidine-oxanorbornene polymers increased the amount of induced saddle-splay membrane curvature, and broadened the range of lipid compositions where saddle-splay curvature was induced. The enhancement of saddle-splay curvature generation and relaxation of lipid composition requirements via addition of hydrophobicity is consistent with activity profiles. While PGON polymers displayed selective antimicrobial activity against prototypical (Gram positive and negative) bacteria, polymers with phenyl and butyl groups were also active against red blood cells. Our results suggest that it is possible to achieve deterministic molecular design of pore forming peptides.

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Section: Resultsmentioning

confidence: 99%

Molecular Basis for Nanoscopic Membrane Curvature Generation from Quantum Mechanical Models and Synthetic Transporter Sequences

et al. 2012

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“…35,36 They speculated that the likely reason was the aggregation of L-lysine: this might arise from the presence of a bridging water molecule between each of N-H groups of the lysine-lysine pair. However, any such bridging would likely also impact that water's structure.…”

Section: Discussionmentioning

confidence: 99%

Spectroscopic Studies of Solutes in Aqueous Solution

et al. 2008

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Absorption and fluorescence characteristics of aqueous solutions of salts, sugars, and amino acids were studied using UV-vis spectroscopy and spectrofluorometry. Motivation stemmed from unanticipated absorption spectral and fluorescence features of the "exclusion zone" seen adjacent to various hydrophilic surfaces. Those features implied a structure distinct from that of bulk water (Adv. Colloid Interface Sci. 2006, 127, 19). Absorption peaks at approximately 270 nm similar to those observed in the exclusion zone were seen in solutions of the following substances: salts, Nafion 117 solution/film, l-lysine, d-alanine, d-glucose and sucrose. To determine the fate of the absorbed energy, we studied the fluorescence properties of these solutions. The salts showed fluorescence emission around 480-490 nm under different excitation wavelengths. The fluorescence intensity of LiCl was higher than NaCl, which was in turn higher than KCl-the same ordering as the absorption intensities. Fluorescence of Nafion 117 solution/film, l-lysine, d-alanine, d-glucose and sucrose were observed as well, with multiple excitation wavelengths. Hence, at least some of the absorbed energy is released as fluorescence. The results show features closely similar to those observed in the exclusion zone, implying that the aqueous region around the solutes resembles the aqueous zone adjacent to hydrophilic surfaces. Both may be more extensively ordered than previously thought.

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“…As PLL lacks any aromatic residue that can contribute to fluorescence, the origin of the observed fluorescence can be attributed to intramolecular interactions between side chains of lysine residues in solution [24,25], and the fluorescence intensity showed a more rapid increase with concentration (data not shown) because of an increase in the population of lysine-lysine pairs. The excitation wavelength of PLL at 290 nm has been used to evaluate the changes in the fluorescence intensity of the glycated PLL at the emission wavelength of 325 nm.…”

Section: Discussionmentioning

confidence: 99%