title: Specific binding of Cu(II) ions by leucine-enkephalin analogs.
abstract: Results are reported from a potentiometric and spectroscopic (UV-visible, CD, and ESR) of the protonation constants and Cu(II)-complex stability constants of leucine enkephalin amide (H-Tyr-Gly-Gly-Phe-Leu-NH2, Leu-EN-amide) and two nitro analogs having 4-nitro substituent on the phenyl ring of the Phe residue, (H-Tyr-Gly-Gly-Phe(NO2)-LeuNH2, Leu-EN(nitro)- amide) and the other one with a sarcosine residue replacing the Gly3 residue (Leu-ENSar-amide). Over the pH range of 6-8.5, Leu-EN-amide interacts more strongly with Cu(II) than does the methionine analog, forming a more stable complex with three nitrogens coordinated. The Sar residue acts as a "breakpoint" to the formation of 3N or 4N complexes and, as a result, causes the formation of dimeric complexes bonded through the amino-N, a deprotonated peptide-N- and deprotonated Tyr-O- donors.
authors.affiliation: Institute of Chemistry, University of Wroclaw, Poland.
authors.forename: T
authors.initials: T
authors.lastname: Kowalik-Jankowska
authors.forename: C O
authors.initials: CO
authors.lastname: Onindo
authors.forename: H
authors.initials: H
authors.lastname: Kozlowski
authors.forename: L D
authors.initials: LD
authors.lastname: Pettit
authors.forename: L
authors.initials: L
authors.lastname: Lankiewicz
authors.forename: M
authors.initials: M
authors.lastname: Jasionowski
mesh_terms: D000595:Amino Acid Sequence; D003300:Copper / Q000737:chemistry*; D004743:Enkephalin, Leucine / Q000031:analogs & derivatives* / Q000737:chemistry; D006863:Hydrogen-Ion Concentration; D008969:Molecular Sequence Data
chemical_list: C096537:tyrosyl-glycyl-glycyl-(4-nitro)phenylalanyl-leucinamide; C096538:tyrosyl-glycyl-sarcosyl-(4-nitro)phenylalanyl-leucinamide; D004743:Enkephalin, Leucine; C029940:enkephalin-Leu, NH2(3)-; D003300:Copper