Fluorescent Environment-Sensitive Dyes as Reporters of Biomolecular Interactions - Progress in Molecular Biology and Translational Science - page 52

HO

N

O

O

O

O

Synthetic-labeled peptide

1.4

1.2

1.0

0.8

0.6

0.4

+ Antibody
fragment

0.2

400 450 500

Wavelength (nm)

550 600

Figure 2.9 Chemical structure of the peptide biosensor and its two-color fluorescence
response to interaction with the antibody fragment. 62

hydration of the peptide labeling site upon its interaction with the target
peptide. Following a similar approach, another biosensor was developed
( Fig. 2.9 ), in which peptides labeled at the N-terminus were used for specific
detection of an antibody fragment scFv. 63 Studies of different fluorescent
peptide conjugates revealed that the response to the interaction event
requires optimal distance between the fluorophore and the peptide interac-
tion site. These works show the possibility of transforming a peptide,
representing a minimized analyte binding site, into a ratiometric biosensor
molecule by functionalization with a fluorophore.
Another important aspect is monitoring protein aggregation, which
commonly leads to the dramatic changes in the protein environment at their
interface. A current challenge in this field is to monitor the early and inter-
mediate stages of a -synuclein aggregation, a process associated with
Parkinson's disease. 64 To this end, an Ala

Cys mutant of a -synuclein
was labeled with the thiol-reactive 3HC-B derivative and used as a sensor
of the a -synuclein aggregation. 65 Strong changes in the dual emission of
the label resulted from protein aggregation, allowing continuous monitoring

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