The photophysical properties of protected nonnatural amino acids Boc–l-Dap(7DEAC)–OMe (7DEAC: 7-diethylaminocoumarin) and Boc–l-Dap(C343)–OMe (C343: coumarin 343) were investigated to evaluate the suitability of these amino acids as fluorescent units in peptide-based fluorescent biosensors. The absorption and fluorescence spectra of Boc–l-Dap(7DEAC)–OMe and Boc–l-Dap(C343)–OMe exhibited significant red shifts with increasing solvent polarity. The fluorescence quantum yield and lifetime of Boc–l-Dap(7DEAC)–OMe solutions decreased remarkably with increasing solvent polarity, whereas those of Boc–l-Dap(C343)–OMe were slightly affected by the solvent polarity. Fluorescent peptides H–Dap(7DEAC)–LLA–OMe (1), H–Dap(7DEAC)–KLA–OMe (2), and H–Dap(7DEAC)–ELA–OMe (3) labeled with environment-sensitive 7DEAC were synthesized to examine the interactions of these labeled peptides with lipid membranes and living cells. Neutral 1,2-dimyristoyl-sn-glycero-3-phosphocholine (DMPC) and anionic 1,2-dimyristoyl-sn-glycero-3-[phospho-rac-(1-glycerol)] (DMPG) liposomes were used to investigate peptide–membrane interactions. Hydrophobic peptide 1 exhibited high affinities to both DMPC and DMPC/DMPG mixed membranes. Of the three peptides, cationic peptide 2 exhibited the strongest affinity to DMPC/DMPG membranes, whereas anionic peptide 3 showed a much lower affinity to DMPC/DMPG membranes. These results could be interpreted based on hydrophobic and electrostatic interactions between the peptides and membranes. Peptide 1 was efficiently internalized into HeLa cells, whereas peptides 2 and 3 showed a much lower intracellular delivery.
研究了受保护的非天然
氨基酸Boc–l-Dap(7D
EAC)–OMe (7D
EAC: 7-
二乙基氨基
香豆素)和Boc–l-Dap(C343)–OMe (C343:
香豆素343)的光物理性质,以评估这些
氨基酸作为肽基荧光
生物传感器的荧光单元的适用性。Boc–l-Dap(7D
EAC)–OMe和Boc–l-Dap(C343)–OMe的吸收和荧光光谱随着溶剂极性的增加呈现出显著的红移。Boc–l-Dap(7D
EAC)–OMe溶液的荧光量子产率和寿命随着溶剂极性的增加显著降低,而Boc–l-Dap(C343)–OMe的荧光量子产率和寿命受溶剂极性的影响较小。合成了标记有环境敏感的7D
EAC的荧光肽H–Dap(7D
EAC)–L
LA–OMe (1)、H–Dap(7D
EAC)–K
LA–OMe (2)和H–Dap(7D
EAC)–E
LA–OMe (3),以检查这些标记肽与脂质膜和活细胞的相互作用。使用中性的
1,2-二肉豆蔻酰-sn-甘油-3-
磷酸胆碱(
DMPC)和阴离子的
1,2-二肉豆蔻酰-sn-甘油-3-[
磷酸-rac-(1-
甘油)] (
DMPG)脂质体来研究肽-膜相互作用。疏
水性肽1对
DMPC和
DMPC/
DMPG混合膜表现出高亲和力。在这三种肽中,阳离子肽2对
DMPC/
DMPG膜表现出最强的亲和力,而阴离子肽3对
DMPC/
DMPG膜的亲和力要低得多。这些结果可以根据肽和膜之间的疏
水性和静电相互作用来解释。肽1被有效地内化到He
LA细胞中,而肽2和3的细胞内递送要低得多。