Amino acids, photochemical changes

Jonas, M., Blechert, S., and Steckhan, E. (2001) Photochemically induced electron transfer (PET) catalyzed radical cyclization A practical method for inducing structural changes in peptides by formation of cyclic amino acid derivatives. Journal of Organic Chemistry, 66, 6896-6904. 

J.I. Goes, N. Handa, S. Taguchi, T. Hama (1995). Changes in the patterns of biosynthesis and amino acids in marine phytoplankters exposed to ultraviolet-B radiation nitrogen limitation implicated. Photochem. PhotobioL, 62, 703-710. 

In addition to the identification of crystal moditications, SSNMR has been used to monitor reactivity and phase changes in different polymorphic forms. For instance, Harris and Thomas (1991) followed the photochemical conversion of formyl-fran -cinnamic acid with SSNMR (see also Section 6.4). Variable temperature techniques have been used to study the interconversion of four polymorphic modifications of sulphanilamide (/ -amino-benzenesulphonamide), including interpretation of at least some of the molecular motions during the course of the transformation (Frydman et al. 1990). A similar combination was augmented with colourimetric techniques to study the coexistence of two phases in the course of a phase transition (Schmidt et al. 1999). Of course, differences between unsolvated and solvated or hydrated crystal moditications may also be readily characterized by the SSNMR technique, as was done with the anhydrous and monohydrate of oxyphenbutazone (Stoltz et al. 1991). Due to the availability of the crystal structures for both modifications the SSNMR results could be interpreted directly in terms of the different atomic environments, especially for the differences in hydrogen bonding in the presence... 

Chang, S.C., MacRobert, A.J., Porter, J.B., and Bown, S.G. (1997) The efficacy of an iron chelator (CP94) in increasing cellular protoporphyrin IX following intravesical 5-amino-levulinic acid administration an in vivo study, J. Photochem. Photobiol. B Biol., 38 114-122. 

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