The alkyl linkers in tandem-homodimers of a β-sheet-forming nonapeptide affect the self-assembled nanostructures

Tandem-Homodimer of a β-Sheet-Forming Short Peptide Inhibits Random-to-β Structural Transition of Its Original Monomer

“…The Aoc8-TD (5.0 and 20 µM) samples showed the same time-dependent profiles as RU003 alone, indicating an inability to inhibit the random-to-β structural transition of RU003 ( Figure S18 and Figure 3E), although 10 µM Aoc8-TD slightly inhibited the structural transition of RU003 by day-2. In all cases, the day-0 CD spectra of samples containing 10 and 20 µM RU003-TD showed a slightly red-shifted negative peak (from 200 to 205 nm), together with a shoulder or weak negative peak around 220 nm, probably due to the early β-sheet structures of RU003 TDs [33].…”

“…Thus, the present CD measurements suggest that RU003 transformed from a random coil to a β-sheet conformation after a lag period. We previously reported time-dependent CD spectra of RU003 TDs alone and found that RU003 TDs quickly adopted stable b-sheet structures, probably due to increased hydrophobicity and extended amide bonds for hydrogen bonds in the literature [33].…”

“…RU003, Abu4-TD, Ape5-TD, Ahx6-TD, Ahp7-TD, and Aoc8-TD were prepared according to the literature [32,33]. Characterization data (HPLC and matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOFMS)) are shown in Figures S1-S12).…”

“…The designs of the β-sheet-forming nonapeptide RU003 and RU003 tandem-homodimers have been described previously [32,33]. Briefly, RU003 comprises two L-isoleucines (Ile) at the 2nd and 8th positions and an aromatic L-2-naphthylalanine (Nal) at the 6th position.…”

“…Thus, the present CD measurements suggest that RU003 transformed from a random coil to a β-sheet conformation after a lag period. We previously reported time-dependent CD spectra of RU003 TDs alone and found that RU003 TDs quickly adopted stable b-sheet structures, probably due to increased hydrophobicity and extended amide bonds for hydrogen bonds in the literature [33]. Figure 2B shows that the CD spectra of the mixture of RU003 (100 µM) and Ape5-TD (10 µM) remained essentially unchanged (random coil conformation) for 4 days, with a strong negative peak at 200 nm, followed by a weak structural transition (a CD spectrum corresponding to mixed random coil and β-sheet conformation) at day-5.…”