A facile and versatile methodology for cysteine specific labeling of proteins with octahedral polypyridyl d⁶ metal complexes.
We have synthesized and characterized four octahedral polypyridyl d(6) metal complexes bearing the 5,6-epoxy-5,6-dihydro-[1,10]phenanthroline ligand (L1) as cysteine specific labeling reagents. The proposed synthetic pathways allow the preparation of the metal complexes containing Re(I), Ru(II), Os(II) and Ir(III) while preserving the epoxide functionality. The complexes were characterized by (1)H and (13)C NMR, mass spectrometry, UV-visible and luminescence spectroscopies as well as cyclic voltammetry. As proof of concept, a set of non-native single cysteine P450 BM3 heme domain mutants previously developed in our laboratory was used to study the labeling reaction. We demonstrate that the proposed labels can selectively react, often in high yield, with cysteine residues of the protein via the nucleophilic thiol ring opening of the epoxide moiety. In addition, under basic conditions, subsequent loss of a water molecule led to the aromatization of the phenanthroline ring on the protein-bound label compounds, as observed by mass spectrometry and luminescence measurements.
San José State University, Department of Chemistry, One Washington Square, San José, CA 95192-0101, United States.
Sudharsan
S
Dwaraknath
San José State University, Department of Chemistry, One Washington Square, San José, CA 95192-0101, United States.
Ngoc-Han
NH
Tran
San José State University, Department of Chemistry, One Washington Square, San José, CA 95192-0101, United States.
Thanh
T
Dao
San José State University, Department of Chemistry, One Washington Square, San José, CA 95192-0101, United States.
Alexander
A
Colbert
San José State University, Department of Chemistry, One Washington Square, San José, CA 95192-0101, United States.
Sarah
S
Mullen
San José State University, Department of Chemistry, One Washington Square, San José, CA 95192-0101, United States.
Angelina
A
Nguyen
San José State University, Department of Chemistry, One Washington Square, San José, CA 95192-0101, United States.
Alejandro
A
Cortez
San José State University, Department of Chemistry, One Washington Square, San José, CA 95192-0101, United States. Electronic address: lionel.cheruzel@sjsu.edu.
Lionel
L
Cheruzel
D001426:Bacterial Proteins / Q000737:chemistry; D056831:Coordination Complexes / Q000737:chemistry*; D003545:Cysteine / Q000737:chemistry*; D003577:Cytochrome P-450 Enzyme System / Q000737:chemistry; D007202:Indicators and Reagents / Q000737:chemistry; D007495:Iridium / Q000737:chemistry; D009251:NADPH-Ferrihemoprotein Reductase / Q000737:chemistry; D009992:Osmium / Q000737:chemistry; D011725:Pyridines / Q000737:chemistry*; D012211:Rhenium / Q000737:chemistry; D012428:Ruthenium / Q000737:chemistry
D001426:Bacterial Proteins; D056831:Coordination Complexes; D007202:Indicators and Reagents; D011725:Pyridines; D009992:Osmium; D007495:Iridium; D012211:Rhenium; D012428:Ruthenium; D003577:Cytochrome P-450 Enzyme System; D009251:NADPH-Ferrihemoprotein Reductase; C052423:flavocytochrome P450 BM3 monoxygenases; D003545:Cysteine
5,6-Epoxy-5,6-dihydro-[1,10]phenanthroline; Biomolecule labeling; Polypyridyl d(6) metal complexes; Sulfhydryl specific