Chemical Modification of Fusion Protein Based on the Thermus thermophilus GroEL Chaperon with AEBSF Protease Inhibitor

Protease inhibitors are routinely used to prepare functional, full-size proteins. Here, we describe modifications of the chimeric protein based on the GroEL chaperon from Thermus thermophilus. Modifications of this chimeric protein resulted from its interaction during sample preparation with an irreversible inhibitor of serine proteases, 4-(2-Aminoethyl)benzenesulfonyl fluoride hydrochloride (AEBSF), which belongs to the sulfonyl-fluoride class of compounds. Protein samples were then identified via MALDI-TOF/TOF after in-gel preparation with trypsin. Modifications of tyrosine and lysine amino acid residues were shown to be present. Also, the availability of the tyrosine residue was found to be a prerequisite for its modification. © 2019, Pleiades Publishing, Inc.