Optimising the synthesis, polymer membrane encapsulation and photoreduction performance of Ru(II)- and Ir(III)-bis(terpyridine) cytochrome c bioconjugates

• Published in: Organic & biomolecular chemistry Vol. 11; no. 28; pp. 4602 - 4612
• Main Authors: Hvasanov, David, Mason, Alexander F, Goldstein, Daniel C, Bhadbhade, Mohan, Thordarson, Pall
• Format: Journal Article
• Language: English
• Published: England 28.07.2013
• Subjects: Acrylates - chemistry; Capsules; Chemistry Techniques, Synthetic; Cytochromes c - chemistry; Iridium - chemistry; Membranes, Artificial; Models, Molecular; Organometallic Compounds - chemical synthesis; Organometallic Compounds - chemistry; Oxidation-Reduction; Photochemical Processes; Polystyrenes - chemistry; Protein Conformation; Pyridines - chemistry; Ruthenium - chemistry
• ISSN: 1477-0520; 1477-0539
• DOI: 10.1039/c3ob40620b

Ruthenium(II) and iridium(III) bis(terpyridine) complexes were prepared with maleimide functionalities in order to site-specifically modify yeast iso-1 cytochrome c possessing a single cysteine residue available for modification (CYS102). Single X-ray crystal structures were solved for aniline and maleimide Ru(II) 3 and Ru(II) 4, respectively, providing detailed structural detail of the complexes. Light-activated bioconjugates prepared from Ru(II) 4 in the presence of tris(2-carboxyethyl)-phosphine (TCEP) significantly improved yields from 6% to 27%. Photoinduced electron transfer studies of Ru(II)-cyt c in bulk solution and polymer membrane encapsulated specimens were performed using EDTA as a sacrificial electron donor. It was found that membrane encapsulation of Ru(II)-cyt c in PS140-b-PAA48 resulted in a quantum efficiency of 1.1 ± 0.3 × 10(-3), which was a two-fold increase relative to the bulk. Moreover, Ir(III)-cyt c bioconjugates showed a quantum efficiency of 3.8 ± 1.9 × 10(-1), equivalent to a ∼640-fold increase relative to bulk Ru(II)-cyt c.