Stabilisierung eines niederaffinen Zustands für Effektoren im menschlichen Ras‐Protein durch Cyclenkomplexe

Abstract

Auf dem Weg zu neuen Hemmstoffen: Die Bindung des Zn2+‐Cyclen‐Komplexes an das menschliche Ras‐Protein stabilisiert eine Proteinkonformation mit schwacher Affinität für Effektoren, was den Komplex zu einer Leitsubstanz für Inhibierungsstudien der Ras‐Effektor‐Wechselwirkung macht. Das Bild zeigt die NMR‐Struktur von Ras⋅Mg2+⋅GppNHp im Komplex mit Zn2+‐Cyclen.

Distinct Conformational States of the Alzheimer β‐Amyloid Peptide Can Be Detected by High‐Pressure NMR Spectroscopy

“…Stabilization of the partially folded state 2' (inhibiting the formation of state 1) by small molecules could also be a suitable mechanism for drug development by weakening the monomer-oligomer interaction similar to the mechanism successfully demonstrated for the interaction of effectors with oncogenic Ras. [28,29] …”

Metal–Bis(2‐picolyl)amine Complexes as State 1(T) Inhibitors of Activated Ras Protein

“…In line with the coordination of Zn 2+ -cyclen with the g-phosphate an interaction with GDP lacking a g-phosphate group was not observed. [16] However, all evidence indicates that interaction site of Zn 2+ -BPA is located outside of the nucleotide binding cleft close to a patch formed by amino acids at positions 38 to 40 and 53 to 58. In line with this model our 31 P NMR data further indicate that M 2+ -BPA, in contrast to the M 2+ -.cyclens, also can interact with Ras in the GDP-bound "off" state ( Figure S5 and Table S3 in the Supporting Information).…”

“…A similar site was also found for M 2+ -cyclen both by NMR spectroscopy and by X-ray crystallography. [16] The second site ( Figure -BPA described here is clearly more powerful than the cyclen derivative. Whereas Zn 2+ -BPA is able to completely shift the equilibrium to state 1(T) at a concentration of 5 mm, for Zn 2+ -cyclen even at a 5 times higher concentration state 1(T) is not completely selected.…”

“…[15] This small ligand is directly coordinated to the g-phosphate of the bound nucleotide. [16] Ligands binding to the g-phosphate group of the nucleotide in the nucleotide-binding cleft are natural candidates for stabilizing state 1(T) since the region around the g-phosphate is accessible only in state 1(T). However, since the general mechanism of action is fundamentally an allosteric mechanism, the ligand-binding site does not have to be located in the active center cleft or the effector interaction site.…”

“…[16] HADDOCK [21] was used for the calculation of complex structures on the basis of the chemical shift perturbation data (ambiguous restraints) from Zn 2+ -BPA titration experiments and the paramagnetic relaxation enhancement data (unambiguous restraints) from Cu 2+ -BPA titration experiments (Table S2). The obtained structures with high HADDOCK scores are all quite similar.…”