Conformational transitions in poly(l-lysine): studies using Fourier transform infrared spectroscopy

Jackson, Michael; Haris, Parvez I.; Chapman, D.

doi:10.1016/0167-4838(89)90121-0

Cited by 167 publications

(184 citation statements)

References 9 publications

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“…Without carbohydrate, drying led to absorption bands at 1625 and 1695 cm Ϫ1 , which are indicative of extended ␤-sheet structure. In the hydrated state poly-lLys exists entirely in the random coil conformation (Tiffany and Krimm, 1969;Jackson et al, 1989;Wolkers et al, 1998d). The above results show that umbelliferose, similar to Suc, can prevent dehydration-induced conformational transitions of poly-l-Lys.…”

Section: Protein Protectionsupporting

confidence: 49%

Changed Properties of the Cytoplasmic Matrix Associated with Desiccation Tolerance of Dried Carrot Somatic Embryos. An in Situ Fourier Transform Infrared Spectroscopic Study1

Wolkers

Tetteroo²,

Alberda

et al. 1999

Plant Physiology

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Abscisic acid-pretreated carrot (Daucus carota) somatic embryos survive dehydration upon slow drying, but fast drying leads to poor survival of the embryos. To determine whether the acquisition of desiccation tolerance is associated with changes in the physical stability of the cytoplasm, in situ Fourier transform infrared microspectroscopy was used. Although protein denaturation temperatures were similar in the embryos after slow or fast drying, the extent of the denaturation was greater after fast drying. Slowly dried embryos are in a glassy state at room temperature, and no clearly defined glassy matrix was observed in the rapidly dried embryos. At room temperature the average strength of hydrogen bonding was much weaker in the rapidly dried than in the slowly dried embryos. We interpreted the molecular packing to be "less tight" in the rapidly dried embryos. Whereas sucrose (Suc) is the major soluble carbohydrate after fast drying, upon slow drying the trisaccharide umbelliferose accumulates at the expense of Suc. The possibly protective role of umbelliferose was tested on protein and phospholipid model systems, using Suc as a reference. Both umbelliferose and Suc form a stable glass with drying: They depress the transition temperature of dry liposomal membranes equally well, they both prevent leakage from dry liposomes after rehydration, and they protect a polypeptide that is desiccation sensitive. The similar protection properties in model systems and the apparent interchangeability of both sugars in viable, dry somatic embryos suggest no special role of umbelliferose in the improved physical stability of the slowly dried embryos. Also, during slow drying LEA (late-embryogenesis abundant) transcripts are expressed. We suggest that LEA proteins embedded in the glassy matrix confer stability to these slowly dried embryos.Desiccation tolerance is the capacity of an organism or tissue to regain vital metabolism after almost complete dehydration. Seeds, pollens, resurrection plants, mosses and ferns, nematodes, tardigrades, yeasts, fungi spores, and bacteria have this capacity (for review, see Crowe et al., 1992Crowe et al., , 1997aVertucci and Farrant, 1995).Carrot (Daucus carota) somatic embryos can be rendered tolerant to severe desiccation by a proper combination of treatments (Tetteroo et al., 1994(Tetteroo et al., , 1995(Tetteroo et al., , 1996(Tetteroo et al., , 1998. Addition of ABA at the proper stage of development, a sufficient slow-drying time (at least 4 d), and a subtle rehydration are the main requirements for the acquisition of desiccation tolerance. Fast drying within a few hours leads to an almost complete loss of viability. These rapidly dried somatic embryos have a considerably greater leakage of K ϩ and soluble carbohydrates than slowly dried embryos. The excessive leakage of cytoplasmic components upon rehydration is associated with irreversible changes in the plasma membranes. Formation of irreversible protein aggregates and an increased T m have been detected in plasma membranes isolated...

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Section: Protein Protectionsupporting

confidence: 49%

Changed Properties of the Cytoplasmic Matrix Associated with Desiccation Tolerance of Dried Carrot Somatic Embryos. An in Situ Fourier Transform Infrared Spectroscopic Study1

Wolkers

Tetteroo²,

Alberda

et al. 1999

Plant Physiology

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“…An assumption in this type of quantitative analysis is that the molar absorptions of the amide I bands assigned to different conformers are equal. This assumption may not be correct in all cases [46][47][48]. However, other studies reported similar intensities for β-stranded and helical polypeptides [47,49], and comparable absorptions were found for β-stranded and random-coiled structures which were obtained from proteins in aqueous solution [50].…”

Section: Figure 7 Dependence Of Fluorescence Energy Transfer On the Rmentioning

confidence: 82%

Structure and organization of the human antimicrobial peptide LL-37 in phospholipid membranes: relevance to the molecular basis for its non-cell-selective activity

Ziv

Lerman

Guðmundsson

et al. 1999

Biochemical Journal

429

197

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The antimicrobial peptide LL-37 belongs to the cathelicidin family and is the first amphipathic α-helical peptide isolated from human. LL-37 is considered to play an important role in the first line of defence against local infection and systemic invasion of pathogens at sites of inflammation and wounds. Understanding its mode of action may assist in the development of antimicrobial agents mimicking those of the human immune system. In vitrostudies revealed that LL-37 is cytotoxic to both bacterial and normal eukaryotic cells. To gain insight into the mechanism of its non-cell-selective cytotoxicity, we synthesized and structurally and functionally characterized LL-37, its N-terminal truncated form FF-33, and their fluorescent derivatives (which retained structure and activity). The results showed several differences, between LL-37 and other native antimicrobial peptides, that may shed light on its in vivoactivities. Most interestingly, LL-37 exists in equilibrium between monomers and oligomers in solution at very low concentrations. Also, it is significantly resistant to proteolytic degradation in solution, and when bound to both zwitterionic (mimicking mammalian membranes) and negatively charged membranes (mimicking bacterial membranes). The results also showed a role for the N-terminus in proteolytic resistance and haemolytic activity, but not in antimicrobial activity. The LL-37 mode of action with negatively charged membranes suggests a detergent-like effect via a ‘carpet-like’ mechanism. However, the ability of LL-37 to oligomerize in zwitterionic membranes might suggest the formation of a transmembrane pore in normal eukaryotic cells. To examine this possibility we used polarized attenuated total reflectance Fourier-transform infrared spectroscopy and found that the peptide is predominantly α-helical and oriented nearly parallel with the surface of zwitterionic-lipid membranes. This result does not support the channel-forming hypothesis, but rather it supports the detergent-like effect.

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“…As demonstrated via Raman spectroscopy, the O-H bending and stretching vibrations of water undergo significant changes in the presence of proteins and other solutes (37,40,41). Increasing evidence also supports the idea that different molar extinction coefficients exist for the various structure types contributing to the protein amide vibrations (33,42,43). Accurate subtraction of background solvent and assignment of the proper weights to the amide band components are critical for obtaining reliable secondary structure estimates, especially in cases involving low protein concentrations.…”

Section: Fourier-transformed Infrared (Ftir)mentioning

confidence: 89%

A Holistic Approach for Protein Secondary Structure Estimation from Infrared Spectra in H2O Solutions

Vedantham

Sparks

Sane

et al. 2000

Analytical Biochemistry

108

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Conformational transitions in poly(l-lysine): studies using Fourier transform infrared spectroscopy

Cited by 167 publications

References 9 publications

Changed Properties of the Cytoplasmic Matrix Associated with Desiccation Tolerance of Dried Carrot Somatic Embryos. An in Situ Fourier Transform Infrared Spectroscopic Study1

Changed Properties of the Cytoplasmic Matrix Associated with Desiccation Tolerance of Dried Carrot Somatic Embryos. An in Situ Fourier Transform Infrared Spectroscopic Study1

Structure and organization of the human antimicrobial peptide LL-37 in phospholipid membranes: relevance to the molecular basis for its non-cell-selective activity

A Holistic Approach for Protein Secondary Structure Estimation from Infrared Spectra in H2O Solutions

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