Charge‐Separated Fmoc‐Peptide β‐Sheets: Sequence‐Secondary Structure Relationship for Arranging Charged Side Chains on Both Sides

Abstract

β‐Sheet formation from fluorenylmethoxycarbonyl (Fmoc)‐substituted polar oligopeptides was demonstrated, where acidic and basic side chains are located separately on either side of the β‐sheet surfaces. For yielding such charge‐separated β‐sheets, self‐assembly of 18 pentapeptides was studied, all of which contain glutamic acid (E), lysine (K), and valine (V). Fmoc‐pentapeptides containing one E and one K all formed fibrillar nanostructures consisting of stacked β‐sheets. On the other hand, Fmoc‐pentapeptides containing two E and two K formed β‐sheet fibrils only when V was located at the center and separated two EK pairs. Photoluminescence studies of these peptides in a glycine buffer containing thioflavin T revealed a clear relationship between the amino acid sequence and secondary structure, where the location of neutral V plays a pivotal role for the β‐sheet formation. The β‐sheet formation propensity was further supported by computer simulation studies with the TANGO algorithm.

Peptide Cross-linkers: Immobilization of Platinum Nanoparticles Highly Dispersed on Graphene Oxide Nanosheets with Enhanced Photocatalytic Activities

“…In the case where the sequence or the length of the peptide was modified to Fmoc-KVVVC ( 4 ) and Fmoc-KVVC ( 5 ), ϕ PD were also smaller (ϕ PD = 27.1 and 23.5%, respectively) than that using 1 (Figures c, S6, and S7d and e), possibly because these peptides hardly form β-sheet (Figure S4). Furthermore, when cysteine in 1 was substituted by glutamic acid (E) without metal-binding ability (Fmoc-VKVVE, 6 ), ϕ PD dropped to 19.6% (Figures c, S6, and S7f), which was in a similar level with that using PtNP/GO composite without peptides (ϕ PD = 18.9%, Figure b, orange). On the basis of the relationship of the dye degradation properties and peptide structure (Table S2), we conclude that Fmoc-VKVVC ( 1 ) affords the best photocatalytic dye degradation performance by the formation of β-sheet, which leads to the separation and integration of the functional groups (charged amino groups and metal binding thiol groups) on the opposite surface of the β-sheet (Figure b).…”

“…Peptides were synthesized by an Fmoc solid phase synthesis method (see Methods and Scheme S1). 14,19,20 We have recently reported that Fmoc-VKVVC (1) (V, valine; K, lysine; C, cysteine; Figure 1a) self-assembles to form an antiparallel βsheet in MeOH, where metal-binding thiol groups of cysteine are integrated on one side, while amino groups of lysine are assembled on the other side of the β-sheet (Figures 1b and S1c); the resultant β-sheets showed strong tendency to redisperse agglomerated MNPs. 14 Notably, we found later that, when an aqueous dispersion of PtNPs was mixed with MeOH solution of β-sheet of 1, PtNPs with less than ∼5 nm diameter selectively adsorbed on the β-sheet, while those with larger sizes (>5 nm) were agglomerated (Figure S 1d−f).…”

“…Peptides are synthesized with a typical Fmoc-solid phase peptide synthesis technique with the following three protocols: (i) Fmoc deprotection , (ii) loading of Fmoc-amino acid monomer , and (iii) cleavage from the resin , as reported previously. ,,, …”

“…Peptides are synthesized with a typical Fmoc-solid phase peptide synthesis technique with the following three protocols: (i) Fmoc deprotection, (ii) loading of Fmocamino acid monomer, and (iii) cleavage f rom the resin, as reported previously. 14,19,20,27 i. Fmoc Deprotection. Typically, piperidine (2 mL) was added to a dimethylformamide (DMF, 8 mL) suspension of Fmoc-SAL resin (0.55 mmol g −1 , 0.5 g, Watanabe Chemical Co.), and the mixture was stirred for 20 min at 25 °C.…”

Supramolecular Hydrogelators and Hydrogels: From Soft Matter to Molecular Biomaterials

“…Peptides functionalized at the N-terminal with large aromatic groups have recently emerged as an exciting class of small molecular hydrogelators. − The most used aromatic group is Fmoc. − As shown in Scheme , shortly after the report of an unexpected small peptidic hydrogelator made of Fmoc- l -Ala- l -Ala ( 300 ) and Fmoc- d -Ala- d -Ala ( 22 ), Ulijn et al reported the development of Fmoc-diphenylalanine (Fmoc-FF or Fmoc-Phe-Phe ( 6 )), one of the most investigated low molecular weight hydrogelators. − The molecules of 6 form hydrogels by adjusting the pH of the aqueous solution of 6 , , by applying 6 to a silica wafer surface, or by the addition of water to a DMSO solution of 6 . , Despite considerable studies on 6 , ,− it was unclear why the mechanical properties reported for the hydrogels of 6 vary significantly, up to 4 orders of magnitude. To address this inconsistency, Adams et al have systematically studied the mechanical properties of hydrogels of 6 prepared using different protocols.…”