Showing papers by "Shinya Tsukiji published in 1998"
TL;DR: It is shown that visible light affects the content of O(2)-bound Mb even in air, indicating that flexible spacers consisting of oxyethylene units do not rigidly fix the distance between Ru(bpy)(3) and the heme center of Mb.
Abstract: A new strategy for semisynthesis of a photoactivatable redox protein is described. Three protohemin molecules with ruthenium tris(2,2‘-bipyridine) attached by different spacers were synthesized. The Ru(bpy)3-protohemins were incorporated into the heme crevice of apomyoglobin (apo-Mb) to yield semisynthetic Mbs carrying Ru(bpy)3 as a photosensitizer (Ru(bpy)3-Mb). The photoactivation properties and the reaction mechanisms of Ru(bpy)3-Mbs were investigated by steady-state photoirradiation and laser flash photolysis. The photoactivation of Ru(bpy)3-Mbs was spectrophotometrically demonstrated by comparison with an intermolecular control, namely an equimolar mixture of Ru(bpy)3 and native Mb. The spacer structure considerably influenced net activation efficiency over a wide pH range as measured by steady-state visible light irradiation and quantum yield. Laser flash photolysis yielded the rate of the photoinduced electron transfer (ET) from the lifetime of the excited Ru(bpy)3 (ket = 4.4 × 107 s-1 for Mb(1b) a...
45 citations