ISSN:
1432-1327
Keywords:
Key words Platinum(II)
;
Migration
;
Oligopeptides
;
Methionine
;
Histidine
Source:
Springer Online Journal Archives 1860-2000
Topics:
Biology
,
Chemistry and Pharmacology
Notes:
Abstract The pH- and time-dependent reaction of [Pt(dien)(H2O)]2+ with the methionine- and histidine-containing peptides H-His-Gly-Met-OH and Ac-His-Ala-Ala-Ala-Met-NHPh at 313 K has been investigated by HPLC and NMR spectroscopy. For both peptides, initial relatively rapid formation of the kinetically favoured methionine S-bound complex is followed by slow intramolecular migration of the [Pt(dien)]2+ fragment to imidazole Nε 2 (or, in the case of H-His-Gly-Met-OH, to a much lesser extent to the competing imidazole Nδ 1) of the histidine side chain over a period of 500 h. Time-dependent studies for the pentapeptide at pH 8.0 demonstrate that this isomerization can take place by either direct S→Nε 2 migration or by a two-step mechanism involving initial Nε 2 coordination of a second [Pt(dien)]2+ fragment and subsequent cleavage of the orginal Pt-S bond in the resulting dinuclear complex. The rate of κS/κN ε 2 isomerization is markedly reduced on lowering the pH to 5.1.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/s007750050327
Permalink
