Fast Photoreduction of a Heme Peptide Encapsulated in Nanostructured Materials

Abstract

Microperoxidase-11 has been immobilized on siliceous materials MCM-41 and SBA-15 and on amino-functionalized SBA-15. Resonance Raman spectroscopy has provided solid evidence that the exogenous species occupy the pores of the mesoporous silica materials. Photoreduction of the microperoxidase-11 Fe(III) center has been observed to occur in the immobilized samples and results in a long-lived stable reduced heme. Reoxidation of the heme occurs upon addition of oxygen, and the redox cycle can be repeated numerous times. The source of the electron resulting in reduction of the heme is proposed to originate from the silica matrix, and functionalization of silica surface is suggested to facilitate electron transfer to the heme.

Bioelectrocatalytic Reduction of Hydrogen Peroxide by Microperoxidase‐11 Immobilized on Mesoporous Antimony‐Doped Tin Oxide

“…The positions of n 4 at 1373 cm À1 , n 3 at 1506 cm À1 , n 2 at 1586 cm À1 and n 10 at 1640 cm À1 are characteristic of an oxidized six-coordinated lowspin heme iron while the n 3 band at 1480 cm À1 indicates the presence of six-coordinated high-spin species. [32][33][34] In contrast, the RR spectra of MP-11 in a mixed solution with PDADMAC as well as immobilized on PDADMAC-modified mpATO demonstrate that in presence of the polyelectrolyte only the 6cLS species is formed confirming the results obtained by UV/Visspectroscopy. The resemblance of the UV/Vis-and Raman spectra of immobilized MP-11 and MP-11 in solution in presence of PDADMAC indicates that no heme dissociation or severe protein denaturation occurs upon adsorption.…”

“…The RR spectrum of MP‐11 in solution in absence of PDADMAC shows the presence of two species. The positions of ν 4 at 1373 cm −1 , ν 3 at 1506 cm −1 , ν 2 at 1586 cm −1 and ν 10 at 1640 cm −1 are characteristic of an oxidized six‐coordinated low‐spin heme iron while the ν 3 band at 1480 cm −1 indicates the presence of six‐coordinated high‐spin species . In contrast, the RR spectra of MP‐11 in a mixed solution with PDADMAC as well as immobilized on PDADMAC‐modified mpATO demonstrate that in presence of the polyelectrolyte only the 6cLS species is formed confirming the results obtained by UV/Vis‐spectroscopy.…”

Proteins in Mesoporous Silicates

“…Of the enzymes immobilized on mesoporous materials, only approximately one third have been examined for their ability to be recycled, and activity losses occur in each cycle in many of these cases. [b] Reuse cytochrome c [64,73,108] no higher enhancedmicroperoxidase-11 [118] no less --lysozyme [84,86] no ---trypsin [41,112,114,126,127] no higher higher [c] enhanced enhanced [c] yes organophosphorus hydrolase [45,91,92] no higher enhanceda-chymotrypsin [57,63,116] no less enhanced yes horseradish peroxidase [62,73] higher [c] enhancedchloroperoxidase [65,90,93,94,106] no less [c] enhanced yes manganese peroxide [66] active enhanced yes papain [27,117] no less enhanced yes pepsin [73] ----bovine serum albumin [71,73] ----subtilisin [62,73] higher [c] enhancedmyoglobin [71,127] ----metmyoglobin [128] higher [c] --hemoglobin [109,110] higher [d] enhanced yes [c]…”

pH‐induced reorientation of microperoxidase‐11 in mesoporous molecular sieves

“…In light of the observations noted with the DR spectroscopy, the oligomerization prevalent in solution is substantially suppressed in the MCM-41 supported form. While the high-wavenumber region shows this unusual behavior, the low-wavenumber region from 100-1000 cm 1 does not show any detectable changes in relative intensities or wavenumbers. Figure 5(a) shows the pH-titration high-wavenumber RR data between 3.5 and 8.5 pH units for MP-11 loaded into MCM-41.…”