Stereoselectivity of Electron and Energy Transfer in the Quenching of (S/R)-Ketoprofen-(S)-Tryptophan Dyad Excited State

Abstract

Photoinduced elementary processes in chiral linked systems, consisting of drugs and tryptophan (Trp) residues, attract considerable attention due to several aspects. First of all, these are models that allow one to trace the full and partial charge transfer underlying the binding of drugs to enzymes and receptors. On the other hand, Trp fluorescence is widely used to establish the structure and conformational mobility of proteins due to its high sensitivity to the microenvironment. Therefore, the study of mechanisms of Trp fluorescence quenching in various systems has both fundamental and practical interest. An analysis of the photo-chemically induced dynamic nuclear polarization (CIDNP) and Trp fluorescence quenching in (R/S)-ketoprofen-(S)-tryptophan ((S/R)-KP-(S)-Trp) dyad carried out in this work allowed us to trace the intramolecular reversible electron transfer (ET) and obtain evidence in favor of the resonance energy transfer (RET). The fraction of dyad’s singlet excited state, quenched via ET, was shown to be 7.5 times greater for the (S,S)-diastereomer than for the (R,S) analog. At the same time, the ratio of the fluorescence quantum yields shows that quenching effectiveness of (S,S)-diastereomer to be 5.4 times lower than for the (R,S) analog. It means that the main mechanism of Trp fluorescence quenching in (S/R)-KP-(S)-Trp dyad is RET.

The Physical Chemistry and Chemical Physics (PCCP) Section of the International Journal of Molecular Sciences in Its Publications: The First 300 Thematic Articles in the First 3 Years

“…We assigned 18 articles to this thematic area, namely [ 128 , 235 , 236 , 237 , 238 , 239 , 240 , 241 , 242 , 243 , 244 , 245 , 246 , 247 , 248 , 249 , 250 , 251 ]. Their distribution within the typing specified in the Introduction is presented in Table 9 .…”

“…Taking this circumstance into account, two basic variants of their systematics are possible—by the nature of the transfer (energy transfer or charge transfer) and by the physicochemical nature of the material, in which such a transfer is carried out. In the variant of systematics by the nature of transfer, all articles presented in this Thematic Area can be divided into those in which studies are related to energy transfer, and those in which studies are related to charge transfer; the first include articles [ 128 , 236 , 237 , 238 , 239 , 241 , 242 , 246 , 247 , 249 ], the second, articles [ 235 , 240 , 243 , 244 , 245 , 248 , 250 , 251 ]. In the variant of systematics by the nature of the material, two types of articles can also be distinguished—those in which the energy/charge transfer is carried out in organic materials, namely [ 128 , 236 , 237 , 238 , 240 , 243 , 244 , 247 , 249 , 250 , 251 ], and those in which this transfer is carried out in inorganic materials [ 235 , 239 , 241 , 242 , 245 , 246 , 248 ].…”

“…In the variant of systematics by the nature of transfer, all articles presented in this Thematic Area can be divided into those in which studies are related to energy transfer, and those in which studies are related to charge transfer; the first include articles [ 128 , 236 , 237 , 238 , 239 , 241 , 242 , 246 , 247 , 249 ], the second, articles [ 235 , 240 , 243 , 244 , 245 , 248 , 250 , 251 ]. In the variant of systematics by the nature of the material, two types of articles can also be distinguished—those in which the energy/charge transfer is carried out in organic materials, namely [ 128 , 236 , 237 , 238 , 240 , 243 , 244 , 247 , 249 , 250 , 251 ], and those in which this transfer is carried out in inorganic materials [ 235 , 239 , 241 , 242 , 245 , 246 , 248 ]. The second variant of the systematics of articles seems to be more expedient, which we will use as the basis for further narration about Thematic Area 8.…”

“…In [ 236 ], the discussion was about the transfer of energy; an example of an article in which the study of charge transfer took place is [ 240 ], in which the intramolecular charge transfer in a probe based on benzothiazole was recorded. These two articles, as well as [ 128 , 244 , 251 ], were devoted to organic abiogenic materials; in other articles of the “organic” profile, namely [ 237 , 238 , 243 , 247 , 249 , 250 ], materials of biological origin, very diverse in terms of their physicochemical characteristics, were used as a medium for the transfer of energy/charge—polypeptides and their derivatives [ 237 , 243 , 250 ], nitrogenase [ 247 ], and various antibiotics [ 249 ]. Among the research articles related to the above processes in inorganic materials, it should be noted that [ 241 ] was devoted to the creation of quantum dots from carbon atoms in an array of tricarbon tetranitride C 3 N 4 , and article [ 246 ] demonstrated the expediency of short-term sonoporation using microbubbles encapsulated by nanoparticles elemental gold in the treatment of liver cancer before radiation therapy.…”

Water-Induced Tuning of the Emission of Polyaniline LEDs within the NIR to Vis Range

“… 1 , 3 , 7 , 8 , 13 , 14 , 18 Such complex problems and systems are very often successfully examined with experimental and theoretical models, supported by computer simulations. 5 − 7 , 9 , 17 , 19 …”