Premium
Synthesis of isotopically labeled all‐ trans retinals for DNP‐enhanced solid‐state NMR studies of retinylidene proteins
Author(s) -
Leeder Alexander J.,
Brown Lynda J.,
BeckerBaldus Johanna,
Mehler Michaela,
Glaubitz Clemens,
Brown Richard C.D.
Publication year - 2018
Publication title -
journal of labelled compounds and radiopharmaceuticals
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.432
H-Index - 47
eISSN - 1099-1344
pISSN - 0362-4803
DOI - 10.1002/jlcr.3576
Subject(s) - chemistry , polyene , retinal , rhodopsin , retinaldehyde , chromophore , solid state nuclear magnetic resonance , stereochemistry , nuclear magnetic resonance spectroscopy , ring (chemistry) , ionone , magic angle spinning , photochemistry , nuclear magnetic resonance , biochemistry , organic chemistry , physics
Three all‐ trans retinals containing multiple 13 C labels have been synthesized to enable dynamic nuclear polarization enhanced solid‐state magic angle spinning NMR studies of novel microbial retinylidene membrane proteins including proteorhodpsin and channelrhodopsin. The synthetic approaches allowed specific introduction of 13 C labels in ring substituents and at different positions in the polyene chain to probe structural features such as ring orientation and interaction of the chromophore with the protein in the ground state and in photointermediates. [10‐18‐ 13 C 9 ]‐All‐ trans ‐retinal ( 1b ), [12,15‐ 13 C 2 ]‐all‐ trans ‐retinal ( 1c ), and [14,15‐ 13 C 2 ]‐all‐ trans ‐retinal ( 1d ) were synthesized in in 12, 8, and 7 linear steps from ethyl 2‐oxocyclohexanecarboxylate ( 5 ) or β‐ionone ( 4 ), respectively.