Clinical Spectroscopic Diagnostics

Heme (iron protoporphyrine IX) is a prosthetic group in many bacterial proteins as well as an important iron source and therefore crucial for survival and growth of bacteria. Many bacterial heme-binding proteins are known to play a significant role in heme uptake, transport, regulation and degradation.[1-3] In addition, heme can also regulate a protein’s activity via transient binding to a short sequence stretch on its surface leading to e.g. a conformational change.[4] Coordination of heme is often realized via amino acids such as cysteine, histidine or tyrosine.[5] However, further effects like hydrogen bonding or hydrophobic interactions of the porphyrine ring with adjacent amino acids considerably contribute to a sufficient ligand binding.[6] Using UV-vis spectroscopy we investigated heme-binding capacities of cysteine-based peptides derived from both, a combinatorial peptide library[5] and a literature-based approach. Application of resonance Raman-, EPR- and NMR-spectroscopy revealed insight into how sequence characteristics determine heme-peptide binding modes. The study of the binding behavior of heme to bacterial proteins might provide useful knowledge about heme uptake and processing strategies of bacteria.