Hydrochloric acid solution

DMATMPyP
was obtained by the methylation
of meso-(N,N-dimethyl-4-aminophenyl)-tris(p-pyridyl)porphyrin (DMATPyP). Synthesis of DMATPyP was
according to the previously reported method.^{47 (link)} To obtain DMATMPyP, the methylation of DMATPyP was carried out according
to the literature.^{48 (link),49 (link)} Details about the synthesis and
characterization of DMATMPyP are described in the Supporting Information. The spectroscopic-grade distilled
water was purchased from Dojin Chemicals Co. (Kumamoto, Japan). Sodium
phosphate buffer (pH 7.6) and NADH were from Nakalai Tesque Inc. (Kyoto,
Japan). Dimethyl sulfoxide-d₆ and sodium
azide were from FUJIFILM Wako Pure Chemical Co. (Osaka, Japan). Methyl
iodide and diethyl ether were from Kanto Chemical Co., Inc. (Tokyo,
Japan). HSA was purchased from Sigma-Aldrich Co. LLC. (St. Louis,
MO, USA). These reagents were used as received. A sodium phosphate
buffer (pH 6.4) was prepared from disodium hydrogen phosphate dodecahydrate
and sodium dihydrogen phosphate dihydrate (Nacalai Tesque, Inc., Kyoto,
Japan). Sodium phosphate buffers (pH 4.4 and 3.2) were prepared from
sodium dihydrogen phosphate dihydrate (Nacalai Tesque, Inc.) and 0.05
M phosphoric acid (Kanto Chemical, Co. Inc., Tokyo. Japan). An acidic
solution (pH 2.0) was prepared from 0.1 M hydrochloric acid solution
(FUJIFILM Wako Pure Chemical Co.) and distilled water (FUJIFILM Wako
Pure Chemical Co.).