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Peptide conjugate molecules comprising a gold-binding peptide (e.g., AYSSGAPPMPPF) attached to an aliphatic tail have proven to be powerful agents for directing the synthesis and assembly of gold nanoparticle superstructures, in particular chiral helices having interesting plasmonic chiroptical properties. The composition and structure of these molecular agents can be tailored to carefully tune the structure and properties of gold nanoparticle single and double helices. To date, modifications to the β-sheet region (AYSSGA) of the peptide sequence have not been exploited to control the metrics and assembly of such superstructures. We report here that systematic peptide sequence variation in a series of gold-binding peptide conjugate molecules can be leveraged not only to affect the assembly of peptide conjugates but also to control the synthesis, assembly, and optical properties of gold nanoparticle superstructures. Depending upon the hydrophobicity of a single-amino acid variant, the conjugates yield either dispersed gold nanoparticles or helical superstructures. These results provide evidence that subtle changes to peptide sequence, via single-amino acid variation in the β-sheet region, can be leveraged to program structural control in chiral gold nanoparticle superstructures.
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Amino Acid Derivatives of Chlorin-e6—A Review
Details of the structural elucidation of the clinically useful photodynamic therapy sensitizer NPe6 (15) are presented. NPe6, also designated as Laserphyrin, Talaporfin, and LS-11, is a second-generation photosensitizer derived from chlorophyll-a, currently used in Japan for the treatment of human lung, esophageal, and brain cancers. After the initial misidentification of the structure of this chlorin-e6 aspartic acid conjugate as (13), NMR and other synthetic procedures described herein arrived at the correct structure (15), confirmed using single crystal X-ray crystallography. Interesting new features of chlorin-e6 chemistry (including the intramolecular formation of an anhydride (24)) are reported, allowing chemists to regioselectively conjugate amino acids to each available carboxylic acid on positions 131 (formic), 152 (acetic), and 173 (propionic) of chlorin e6 (14). Cellular investigations of several amino acid conjugates of chlorin-e6 revealed that the 131-aspartylchlorin-e6 derivative is more phototoxic than its 152- and 173-regioisomers, in part due to its nearly linear molecular conformation.
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- Award ID(s):
- 2055190
- PAR ID:
- 10425626
- Date Published:
- Journal Name:
- Molecules
- Volume:
- 28
- Issue:
- 8
- ISSN:
- 1420-3049
- Page Range / eLocation ID:
- 3479
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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- Free Publicly Accessible Full Text
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Accepted Manuscript1.0
- Journal Article:
- https://doi.org/10.3390/molecules28083479
