Infrared noncovalent complexes

Dybvik, A.I., Norberg, A.L, Schute, V., Soltwisch, J., Peter-Katahnic,)., Virum, K.M., Eijsink, V.G.H., Dreisewerd, K., Mormann, M., and Sorlie, M. (2011) Analysis of noncovalent dritinase-chito-oUgosaccharide complexes by infrared-matrix assisted laser desorption... 

Some bis-squaraine derivatives 2.211 have been prepared as near-infrared emissive fluorophores, where two squaraine units were linked by oligothiophene spacers (Chart 1.43) [300], These dyes showed absorption bands at 780 and 700 nm with high molar absorptivities. Additionally, by increasing the number of thiophene units, blue shifts in the absorption bands were observed. The noncovalent interactions with human serum albumin (HAS) and BSA have been studied in trizma buffer and showed the formation of 1 1 complexes concomitant with a fluorescence enhancement. 

Examples from other groups include gas-phase thermal dissociation experiments, implemented with blackbody infrared radiative dissociation (BIRD) and FT-ICR MS on a series of protein-carbohydrate complexes, and the detection of fusion peptide-phospholipid noncovalent interactions using nano-ESI FTICR-MS. An interesting example of protein-DNA interaction smdied by ESI-MS is the trp repressor-DNA operator complex. Escherichia coli trp apo-repressor (TrpR), a homodimer, is a DNA-binding protein that binds to two molecules of co-repressor L-tryptophan to form a holorepressor complex at higher salt concentrations. The mass spectrum of noncovalent... 

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