Mercury peptide complexes

The peptide fragments of metalloth-ioneins Lys-Cys-Thr-Cys-Cys-Ala [56-61] (FT) were studied by different electrochemical techniques. The cyclic voltam-metric behavior of the peptide fragment in the presence of Cd(II) indicated two reversible electrochemical processes due to the oxidation of the mercury electrode in the presence of CdFT and reduction of CdFT complex, both from the dissolved and adsorbed state [105]. The influence of the experimental conditions on electroreduction of Cd-metallothioneins... 

Other Metal-Peptide and -Protein Interactions.—The determination of protein-bound trace elements in biological material by neutron activation analysis has been described Zn, Hg, Cu, and Se were accurately detected in human liver samples, provided that most of the element concerned was protein bound. An interaction of mercury with a protein or a protein-DNA complex has been invoked to explain the partitioning of the metal in euchromatin over heterochromatin (from mouse liver nuclei) by a 10 1 ratio. " Bovine retinas, isolated rod outer segments and emul-phogene extracts of rod outer segments have been shown to contain appreciable amounts of Zn ", Ca and the zinc levels being light sensitive. 

In order to understand the biochemistry of mercury more completely, it is important to describe the chemistry of this element with sulfhydryl donors in the most common coordination environments. Ideally, one would examine mercuric complexes within a construct that was basically invariant, but which allowed for preparation of mercury compounds in the most common structures. The desired coordination modes include linear (or slightly bent) for 2-coordinate complexes, trigonal planar (or slightly T-shaped) for 3-coordinate compounds and tetrahedral for 4-coordinate complexes. Figure 1. Unfortunately, diere are no known native systems that allow for this diversity of metal coordination geometry. However, given advances in peptide synthesis and the prediction of... 

Thiols at a concentration of 10 to 40 mM also act as antagonists to the action of neuropeptides on rat uterus, but not to their pressor effect Such a difference could be due to a difference in the receptors. Thioglycollate (10 mM) and cysteine (10 mM) inhibit the permeability response of the toad bladder to oxytocin or vasopressin. Gluthathione has a similar effect These actions of the peptides are also inhibited after incubation of the tissues in the presence of either N-ethyl- or N-phenylaleimide which form covalent bonds with sulphydryl groups or complex mercury mercaptides (p-hydroxy-mercury-benzoate, p-chloro-mercury-benzoate). These results show that the receptor presents in its constitution some functional sulphydryl groups. 

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