3.4 Methods and Materials
91
H
N
N
H
H
N
N
H
O
O
O
O
H
N
N
H
H
N
N
H
O
O
O
O
NH2
HO
OH
NH2
O
HN
HO
N
NH
N
H
O
S
H
N
N
H
H
N
O
O
OH
O
Ac
PhR
H
N
N
H
H
N
N
H
O
O
O
O
H
N
N
H
H
N
N
H
O
O
O
O
NH2
HO
OH
NH2
O
HN
HO
N
NH
N
H
O
S
H
N
N
H
H
N
O
O
OH
O
Ac
MeR
O
HO
HO
O
O
NH
S
H
N
N
H
H
N
N
H
O
O
O
O
H
N
N
H
H
N
N
H
O
O
O
O
NH2
HO
OH
NH2
O
HN
HO
N
NH
N
H
O
S
H
N
N
H
H
N
O
O
OH
O
H
N
N
H
H
N
N
H
O
O
O
O
H
N
N
H
H
N
N
H
O
O
O
O
NH2
HO
OH
NH2
O
HN
HO
N
NH
N
H
O
S
H
N
N
H
H
N
O
O
OH
O
MeR-FITC
O
H
N
O
H
N
PhR-Cy 3
N
N
O
O
HO
HO
O
O
NH
S
H
N
N
H
H
N
N
H
O
O
O
O
H
N
N
H
H
N
N
H
O
O
O
O
NH2
HO
OH
NH2
O
HN
HO
N
NH
N
H
O
S
H
N
N
H
H
N
O
O
OH
O
PhR-FITC
O
H
N
Chemical Formula: C76H107N17O18S
Molecular Weight: 1578.85
Chemical Formula: C81H109N17O18S
Molecular Weight: 1640.92
Chemical Formula: C98H121N19O23S2
Molecular Weight: 1997.28
Chemical Formula: C103H123N19O23S2
Molecular Weight: 2059.35
Chemical Formula: C112H148N20O19S
Molecular Weight: 2110.60
Scheme 3.2 The chemical structure of PhR/MeR and fluorescein-labeled PhR/MeR
3.4.4 Flow Cytometry
1. Transfection efficiency
For the flow cytometry of transfection efficiency experiments, cells were treated
with fluoresceinated peptides (5 μM) for up to 4 h at 37°C. After washing with
media, the cells were digested with trypsin (0.25%; Gibco), digestion (2 min,
37°C), washed with PBS, and resuspended in PBS. Cellular fluorescence was
analyzed using a BD FACSCalibur flow cytometer (Becton Dickinson) and
CellQuest Pro (or CFlow plus). The same experiment was performed with 30 min