The design of biomimetic materials through molecular self-assembly is a growing area of modern nanotechnology. With problems of protein folding, self-assembly, and sequence–structure relationships as essential in nanotechnology as in biology, the effect of the nucleation of β-hairpin formation by proline on the folding process has been investigated in model studies. Previously such studies were limited to investigations of the influence of proline on the formation of turns in short peptide sequences. The effect of proline-based triads on the folding of an 11-kDa amyloidogenic peptide GH₆[(GA)₃GY(GA)₃GE]₈GAH₆ (YE8) was investigated by selective substitution of the proline-substituted triads at the γ-turn sites. The folding and fibrillation of the singly proline-substituted polypeptides, e.g., GH6[(GA)3GY(GA)3GE]7(GA)3GY(GA)3PDGAH6 (8PD), and doubly proline-substituted polypeptides, e.g., GH6[(GA)3GY(GA)3GE]3(GA)3GY(GA)3PD[(GA)3GY(GA)3GE]3(GA)3GY(GA)3PDGAH6 (4,8PD), were directly monitored by circular dichroism and deep UV resonance Raman and fluorescence spectroscopies. These findings were used to identify the essential folding domains, i.e., the minimum number of β-strands necessary for stable folding. These experimental findings may be especially useful in the design and construction of peptidic materials for a wide range of applications as well as in understanding the mechanisms of folding critical to fibril formation. © 2015 Wiley Periodicals, Inc. Biopolymers 103: 339–350, 2015.

Substituted alkenyl aryl tetrafluoro-λ⁶-sulfanes have been prepared by the direct addition of readily accessible chlorotetrafluorosulfanyl arenes to primary alkynes. Substitution of an apical fluorine of the pentafluorosulfanyl group enables modulation of the reactivity of this little explored functional group while at the same time facilitating the direct investigation of aryl substituent effects on the aryl tetrafluorosulfanyl-substituted products.

Substituted alkenyl aryl tetrafluoro-λ⁶-sulfanes have been prepared by the direct addition of readily accessible chlorotetrafluorosulfanyl arenes to primary alkynes. Substitution of an apical fluorine of the pentafluorosulfanyl group enables modulation of the reactivity of this little explored functional group while at the same time facilitating the direct investigation of aryl substituent effects on the aryl tetrafluorosulfanyl-substituted products.

The design and synthesis of pentafluorosulfanyl-containing heptad amino acid sequence was described. The three-dimensional conformation of the peptide was investigated by using CYANA (combined assignment and dynamics algorithm for NMR applications) and the integrated autoassignment. This study shows that the one of the diastereomers assumed a very tight coiled conformation in [D₆]DMSO where both pentafluorosulfanyl groups assumed a synclinal relationship. The propensity of the protected heptapeptide to form such a tight coil and of the pentafluorosulfanyl groups to align so uniformly is suggestive of the utility of pentafluorosulfanylated amino acids in promoting conformational control.

A facile preparation of aliphatic 2-pentafluorosulfanyl aldehydes is described. To investigate the utility of the aldehydes as synthetic building blocks, various transformations of the aldehydes were explored. The pentafluorosulfanyl group was stable under a variety of reaction conditions, and the pentafluorosulfanylated products were obtained in moderate to good yields in most cases.

Analogs of pyrazinamide (=pyrazine-2-carboxamide; PZA), an essential component of short-course antituberculous chemotherapy, such as 5-chloropyrazinamide (5-Cl-PZA) act as competitive inhibitors of NADPH binding to purified mycobacterial fatty acid synthase I (FAS I) as shown by Saturation Transfer Difference (STD) NMR studies. In addition, pyrazinoic acid esters (POE) and 5-Cl-POE reversibly bind to FAS I with the relatively greater affinity of longer-chain esters for FAS I, clear from the STD amplification factors. The competitive binding of PZA and 5-Cl-PZA clearly illustrates that both agents bind FAS. In contrast to PZA, at low NADPH concentrations 5-Cl-PZA is a cooperative inhibitor of NADPH binding.