Chirality distribution in the fifth ligand coordination of chlorophylls-c in photosynthetic pigment-protein complexes.

Chlorophyll-c molecules in photosynthetic complexes predominantly coordinate from the β-side, contrasting with the α-ligation preference of other (B)Chls, with 24 of 42 molecules showing this trait.

• Why it matters: Understanding the stereochemistry of ligand coordination in chlorophylls is crucial for elucidating their functional roles in photosynthesis and pigment-protein interactions, yet the distribution of chirality in these complexes remains unclear.
• What they did: The study examined 42 chlorophyll-c molecules across 21 pigment-protein complexes from the Protein Data Bank, analyzing their ligand coordination stereochemistry and binding site preferences.
• The result: Findings reveal a tendency for β-side coordination in Chl-c, often involving carotenoid interactions at specific sites, suggesting that C17 substituent chirality influences pigment-protein complex formation and function.