title: Determination of hemin-binding characteristics of proteins by a combinatorial peptide library approach.
abstract: Studies of the binding of heme/hemin to proteins or peptides have recently intensified as it became evident that heme serves not only as a prosthetic group, but also as a regulator and effector molecule interacting with transmembrane and cytoplasmic proteins. The iron-ion-containing heme group can associate with these proteins in different ways, with the amino acids Cys, His, and Tyr allowing individual modes of binding. Strong coordinate-covalent binding, such as in cytochrome c, is known, and reversible attachment is also discussed. Ligands for both types of binding have been reported independently, though sometimes with different affinities for similar sequences. We applied a combinatorial approach using the library (X)(4) (C/H/Y)(X)(4)  to characterize peptide ligands with considerable hemin binding capacities. Some of the library-selected peptides were comparable in terms of hemin association independently of whether or not a cysteine residue was present in the sequence. Indeed, a preference for His-based (≈39 %) and Tyr-based (≈40 %) sequences over Cys-based ones (≈21 %) was detected. The binding affinities for the library-selected peptides, as determined by UV/Vis spectroscopy, were in the nanomolar range. Moreover, selected representatives efficiently competed for hemin binding with the human BK channel hSlo1, which is known to be regulated by heme through binding to its heme-binding domain.
authors: Department of Biochemistry and Biophysics, Friedrich Schiller University of Jena, Hans-Knöll-Strasse 2, 07745 Jena, Germany.
authors: Toni
authors: T
authors: Kühl
authors: Nirakar
authors: N
authors: Sahoo
authors: Melanie
authors: M
authors: Nikolajski
authors: Bernhard
authors: B
authors: Schlott
authors: Stefan H
authors: SH
authors: Heinemann
authors: Diana
authors: D
authors: Imhof
mesh_terms: D000595:Amino Acid Sequence; D001483:Base Sequence; D020650:Combinatorial Chemistry Techniques; D006427:Hemin / Q000378:metabolism*; D019151:Peptide Library; D011485:Protein Binding; D011506:Proteins / Q000737:chemistry / Q000378:metabolism*; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization; D013056:Spectrophotometry, Ultraviolet
chemical_list: D019151:Peptide Library; D011506:Proteins; D006427:Hemin