HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Österberg, R. Articles by Sjöberg, B. Search for Related Content PubMed PubMed Citation Articles by Österberg, R. Articles by Sjöberg, B. Social Bookmarking                      What's this?

The Metal Complexes of Peptides and Related Compounds

III. COPPER(II) COMPLEXES OF GLYCYLGLYCYLGLYCINE IN 3.0 m (Na)ClO₄ MEDIUM

From the ¹ From the Department of Medical Biochemistry, University of Göteborg, Göteborg, Sweden

The copper(II) equilibria of triglycine have been investigated in 3.0 m (Na)ClO₄ medium at 25° with glass and copper amalgam electrodes. The range of B, the total concentration of copper(II) ions, was 1 to 100 mm; the range of A, the total concentration of triglycine, was 2 to 250 mm; and the pH range was 1.5 to 11. The dipolar ion form of triglycine = HA, Y = (H - h)/A, h = [H⁺], and b = [Cu²⁺].

Two sets of data (Y against log h at constant A, B) and (log B/b against A at constant h, B) were recorded. They were treated independently, first by the use of various graphical methods assuming the existence of any species of the type Cu_pH_qA_r^(2p+q-r)+ and then by the use of the general (least squares) minimizing computer program, Letagrop (19). The mean composition of the complexes and the "best" sets of equilibrium constants are tabulated.

It is concluded that mononuclear species CuH_qA^(1+q)+, having q = 1, 0, -1, -2, predominate at low B and A. At higher concentrations (10 mm), there is also evidence for some CuH_qA₂^q+ and Cu₂H_qA₂^(2+q)+. Of these, species with (p, q) equal to (1, 0), (1, -1), (1, -2) and (2, 1), (2, 0) (2, -2), (2, -4) give the best agreement with the experimental data. Deviations can largely be described to small analytical errors but may also indicate some minor species, if so probably CuH₂A₂²⁺ and Cu₂H₂A₂⁴⁺.

CiteULike    Complore    Connotea    Del.icio.us    Digg    Reddit    Technorati    What's this?