Interactions of chlorophyll a with synthesized peptide in aqueous solution

✍ Scribed by Alina Dudkowiak; Chikashi Nakamura; Takaaki Arai; Jun Miyake

• Publisher: Elsevier Science
• Year: 1998
• Tongue: English
• Weight: 875 KB
• Volume: 45
• Category: Article
• ISSN: 1011-1344
• DOI: 10.1016/s1011-1344(98)00158-4

✦ Synopsis

The interactions between chlorophyll a and synthesized peptides have been studied using optical spectroscopy. Three 30-residue peptides are designed and synthesized: an amphiphilic peptide without histidine (L), an amphiphilic peptide with histidine (L/H) and a hydrophilic peptide (K/E). These peptide properties thereby allow us to examine the effect of the peptide hydrophobicity and/or histidine residue on pigment-peptide interactions. On mixing with peptides, chlorophyll a has a main absorption band in the Q, region with the maximum at 672 nm. For all three peptides, fluorescence patterns show that at a low concentration of the peptide (0.05 mM) in aqueous solution, the energy is transferred among various forms of the pigment. Only peptide L/H at high concentration (0.5 mM) in solution retains the Q, baud of chlorophyll a at 672 nm, and the emission is that typically seen for the monomeric form of the pigment. The aggregation of chlorophyll n is suppressed most strongly in the presence of the peptides L/H. The results suggest that chlorophyll a is ligated to a histidine residue, located in the hydrophobic region of the peptides L/H, and is surrounded or shielded by the peptide a-helixes.