The effect of chloroplatinite on the 1H NMR spectrum of ribonuclease Solvent accessibility of methionine residues

Interactions of carboplatin and oxaliplatin with proteins: Insights from X-ray structures and mass spectrometry studies of their ribonuclease A adducts

“…As previously found for cisplatin [15] and chloroplatinite (PtCl 4 2− ) [20], the RNase A-carboplatin interaction in both A and B molecules mainly occurs at the SD atom of the side chain of Met29. However, due to unclear electron density maps likely associated with low occupancy and to the possible conformational disorder of this site, the local environment of the bound Pt(II) center, in the RNase A-carboplatin adduct, could not be unambiguously determined ( Fig.…”

“…Yet, the structural information concerning the interactions of platinum drugs with proteins and the characterization of the resulting adducts is quite limited [8][9][10][11]. In particular, while the interaction between cisplatin and proteins is underscored by a number of biochemical, biophysical and structural studies [12][13][14][15][16][17][18][19][20], the formation of oxaliplatin and carboplatinprotein adducts is far less explored and understood [21][22][23][24].…”

“…RNase A was chosen as a model to study protein interactions with Pt-based [15,20,25,26] and other metal drugs [27,28], since it is a stable, small, well characterized protein that is commercially available at low cost; in addition, it is easy to crystallize, forming crystals resistant to soaking under different experimental conditions. This protein is frequently used as a model system also in many other fields, including protein chemistry, enzymology, chemical synthesis and structural biology [29].…”

The binding of platinum complexes to tuna cytochrome c

“…[PtC14]2has also been used as an n.m.r. probe for resonances of exposed residues ;Sadler et al (1974) have shown it binds to Met-29 of ribonuclease. The work reported in the present paper shows that the binding of [PtCl412-and cis-fPtCl2(NH3)21 to Met-65 of tuna cytochrome c causes only a local, small, structural perturbation to the protein.…”

Cross-linked metalloproteins: novel systems for the study of intraprotein electron-transfer reactions

“…It labels Met 65in ferricytochrome c from horse virtually exclusively although incubation atpH 6.2 resulted in very slight additional labeling of His 33(43). Studies by 1H NMR spectroscopy showed that, atpH 5.5, FtCl^^binds exclusively to methionine: to Met 29 in ribonuclease(46) and, again, to Met 65 in cytochrome c A^m tuna(47). We carried out the incubation at pH 5.5, so that the imidazole side chain, whose pE^ is 6.4(48), is protonated and unreactive.…”