Polarity-tunable and wavelength-tunable bacteriochlorins bearing a single carboxylic acid or NHS ester. Use in a protein bioconjugation model system

摘要: To broaden the scope of near-infrared (NIR)-active chromophores available for bioconjugation with proteins, 10 new bacteriochlorins have been synthesized: six are lipophilic and bear a carboxylic acid tether; four hydrophilic acids one N-hydroxysuccinimido (NHS) ester tether. Each bacteriochlorin exhibits sharp long-wavelength absorption (Qy) band in NIR region (727–823 nm). The were examined DMF (fluorescence quantum yield Φf = 0.037–0.19) whereas (Φf also or aqueous phosphate buffer 0.0011–0.13). Two conjugated to myoglobin (Mb), which contains ∼14 accessible amino groups. Use 2, 10, 50 equivalents bacteriochlorin–NHS (BC7) gave average loadings 0.62, 1.6, 7.1 bacteriochlorins/Mb as determined by spectral comparison strongly absorbing heme ligand. MALDI-MS analysis showed distribution 0–9 bound conjugate sample loading 7.1. Mb–BC7 conjugates exhibited characteristic fluorescence spectra buffer, yet value was markedly low ∼ 0.02) regardless versus that BC7 monomer 0.12), attributed part quenching. Removal revealed loading-dependent Φf, ranged from 0.091 (0.62 loading) 0.023 (7.1 loading). decrease increased is self-quenching perhaps facilitated excited-state energy transfer among (Forster R0 59 A). Taken together, results show facile access collection useful spectroscopic studies, along pigment–protein system serves dual purposes convenient testbed evaluating protein processes well nanosized architecture use photochemical studies.