Simple method to introduce an ester infrared probe into proteins

The ester carbonyl stretching vibration has recently been shown to be a sensitive and convenient infrared (IR) probe of protein electrostatics due to the linear dependence of its frequency on local electric field. While an ester moiety can be easily incorporated into peptides via solid‐phase synthes...

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Bibliographic Details
Published in:Protein science 2017-02, Vol.26 (2), p.375-381
Main Authors: Ahmed, Ismail A., Gai, Feng
Format: Article
Language:English
Subjects:
Alkylation
amyloid
Amyloid beta-Peptides - chemistry
Animals
Bovine serum albumin
Carbonyl compounds
Carbonyls
Cattle
cysteine alkylation
Dependence
Electric fields
Electrostatic properties
Electrostatics
Fibrils
Humans
infrared probe
Insulin
Insulin - chemistry
Methods and Applications
Molecular Probes - chemistry
Peptides
protein hydration
protein modification
Proteins
Serum albumin
Serum Albumin, Bovine - chemistry
Solid phase synthesis
Spectrophotometry, Infrared - methods
Structural integrity
Vibration monitoring
β-Amyloid
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Summary:The ester carbonyl stretching vibration has recently been shown to be a sensitive and convenient infrared (IR) probe of protein electrostatics due to the linear dependence of its frequency on local electric field. While an ester moiety can be easily incorporated into peptides via solid‐phase synthesis, currently there is no method available to site‐specifically incorporate it into a large protein. Herein, we show that it is possible to use a cysteine alkylation reaction to achieve this goal and demonstrate the feasibility of this simple method by successfully incorporating a methyl ester group (CH2COOCH3) into a model peptide (YGGCGG), two amyloid‐forming peptides derived from the insulin B chain and Aβ, and bovine serum albumin (BSA). IR results obtained with those peptide and protein systems further confirm the utility of this vibrational probe in monitoring, for example, the structural integrity of amyloid fibrils and ligand binding‐induced changes in protein local hydration status.
ISSN:0961-8368
1469-896X
DOI:10.1002/pro.3076