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A protein engineering study of the 102-residue protein U1A, which aggregates transiently in the wild-type form during refolding from the guanidinium chloride-denatured state, is carried out to analyze their nature. For the study, a series of mutants with increased aggregation tendencies is prepared by increasing the homology between two beta-strands of U1A and the Alzheimer peptide (beta-AP).

Oligonucleotide containing 5-chlorouracil (ClU) paired opposite guanine (ClU-G) was constructed to gain insight into the reaction between hypochlorous acid (HOCl) from activated neutrophils at sites of inflammation and cytosine analogues which could generate multiple products. The electron-withdrawing 5-chloro substituent was found to facilitate ionization of the ClU N3 proton, promote mispair formation as well as render the glycosidic bond susceptible to base cleavage by DNA repair glycosylases.

A detailed structural study of substrate-triggered (ST) formation and remarkable stability of the C-H bond-cleaving chloroferryl intermediate in the aliphatic halogenase, SyrB2, from the syringomycin E biosynthetic NRPS of Pseudomonas syringae B301D is presented. The directing effect of the carrier protein and consequent tolerance for profound modifications to the target amino acid facilitated the formation of chloroferryl state in the presence of substrates that perturb the ratio of its two putative coordination isomers, lack the target C-H bond (L-Ala-S-SyrB1), or contain a C-H bond of enhanced strength (L-cyclopropylglycyl-S-SyrB1).

Structural characterization of the binding of two halides, iodide and chloride to transthyretin is performed in which chlorides are known to shield charge repulsions at the tetrameric interface of transthyretin improving tetramer stability of the protein. The refined structures showed iodides and chlorides bound at two of the three halogen-binding sites located at the hydrophobic channel.