Synthesis and Spectroscopic Properties of Reconstituted ZincMyoglobin Appending a DNA‐Binding Platinum(II) Complex

Abstract

A reconstituted zinc-myoglobin (ZnMb) dyad, ZnMb-[Pt(bpy)(en)]2+, has been prepared by incorporating chemically-modified zinc-porphyrin, being capable of DNA-binding of the Pt complex, [Pt(bpy)(en)]2+, where bpy and en are 2,2'-bipyridine and ethylenediamine, respectively. The steady-state fluorescence of the cofactor, [Pt(bpy)(mu-enPP)Zn]Cl2, in MeOH indicates that the excited singlet state of zinc--porphyrin was almost quenched, probably because of the strong hydrophobic and pi-pi stacking interactions between the [Pt(bpy)(mu-enPP)Zn]2+ ions. In the reconstituted ZnMb-[Pt(bpy)(en)]2+, the quenching reaction of 1(ZnMb)* with the [Pt(bpy)(en)]2+ moiety does not occur, indicating apo-Mb matrix is essential. On the other hand, when the [Pt(bpy)(en)]2+ moiety was excited, the enhancement of the fluorescence from ZnMb unit was observed. It is suggested that the energy transfer from (1)([Pt(bpy)(en)]2+)* to ZnMb occurs. The spectroscopic changes of ZnMb-[Pt(bpy)(en)]2+ in the presence of calf-thymus DNA were also provided. Soret band at 428 nm gradually decreased, and isosbestic points at 321, 414, and 432 nm were observed with increasing the DNA concentration. When the Pt(II) moiety was excited at lambda(ex) 321 nm, the fluorescence signal around 600 nm similarly decreased. The synthetic manipulation of ZnMb by using a DNA-binding Pt(II) complex demonstrates sensitive fluorescent signal for DNA and valuable information to study photoinduced electron transfer within a Mb-DNA complex.

Ammonium Transport Simulation in Horizontal Soil Columns from a Natural Inland Alkaline Wetland

“…A similar fluorescence quenching mechanism was also reported in metal‐organic compounds 12a–12c. In 2008, Takashima reported the fluorescence of zinc‐porphyrin was almost quenched due to strong π ··· π stacking interactions between the discrete ions 12a. A novel water‐soluble poly( para ‐phenylene) derivative (PBTS) with pendant thymine and sulfonate units was reported.…”

“…It was found that fluorescence quenching happened with higher naphthalene incorporation, which indicated the presence of aggregates in the structure due to extensive π ··· π stacking of the aromatic core 11b. A similar fluorescence quenching mechanism was also reported in metal‐organic compounds 12a–12c. In 2008, Takashima reported the fluorescence of zinc‐porphyrin was almost quenched due to strong π ··· π stacking interactions between the discrete ions 12a.…”

Magnesium Trimethoxyphenylporphyrin Chain Controls Energy Dissipation in the presence of Cholesterol

“…Compound 1 displays emission spectrum with peaks at (612 nm) and (665 nm) in dilute solution (10 −5 M). At realatively higher concentrated solution (3 × 10 −3 M), this emission is significantly quenched due to the known π−π stacking 43 as shown in Figure 3.…”

“…41 Lipids also have pronounced reducing effect on chlorophyll degradation which is not properly understood, inhibiting the enzyme chlorophyllase and it is interesting that chlorophyll degraded product chlorophyllide shows high fluorescence in the presence of lipid. 42,43 To know the photosynthetic activity in the presence of lipid, we studied the luminescence of compound 1. Compound 1 displays emission spectrum with peaks at (612 nm) and (665 nm) in dilute solution (10 −5 M).…”

Influence of position of methoxy groups in Zn-methoxyphenylporphyrins

“…In concentrated solution, porphyrin emission is remarkably decreased due to the known π -π stacking. 38 The luminescence properties of magnesium analogue of compound 3 is known. 39 The thermal studies of several porphyrins are known.…”