title: Heat-resistant oxygen-carrying hemoproteins consist of recombinant xylanases and synthetic iron(II) porphyrin.
abstract: Synthetic iron(II) porphyrin (FeP) is equivalently incorporated into recombinant Thermotoga maritima xylanase B (TMX; family F/10 of glycoside hydrolase), producing a heat-resistant artificial hemoprotein (TMX-FeP) that can bind and release oxygen (O(2)) in aqueous medium (pH 7.3, 25 degrees C) in the same manner as hemoglobin and myoglobin. The oxygenated species was sufficiently stable; the half-lifetime against the ferric state (tau(1/2)) was 5 h. This O(2)-carrying hemoprotein showed a high degree of thermal stability over a wide range of temperatures up to 90 degrees C (tau(1/2) = 5 min at 90 degrees C and 9 min at 75 degrees C). Dictyoglomus thermophilum xylanase B (DTX; family G/11) also incorporates FeP, and DTX-FeP showed identical O(2)-binding parameters and thermostability. TMX-FeP is capable of catalyzing the beta-1,4-d-xylan hydrolysis reaction. Its larger K(m) value compared to that of TMX itself suggested competitive FeP binding to the active site of the host enzyme.
authors.affiliation: Department of Applied Chemistry and Advanced Research Institute for Science and Engineering, Waseda University, 3-4-1 Okubo, Shinjuku-ku, Tokyo 169-8555, Japan.
authors.forename: Teruyuki
authors.initials: T
authors.lastname: Komatsu
authors.forename: Seiji
authors.initials: S
authors.lastname: Ishihara
authors.forename: Eishun
authors.initials: E
authors.lastname: Tsuchida
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Nishide
authors.forename: Chihiro
authors.initials: C
authors.lastname: Morokuma
authors.forename: Satoshi
authors.initials: S
authors.lastname: Nakamura
mesh_terms: D043364:Endo-1,4-beta Xylanases / Q000032:analysis / Q000378:metabolism*; D006420:Hemeproteins / Q000032:analysis / Q000737:chemistry / Q000378:metabolism*; D006358:Hot Temperature; D007501:Iron / Q000032:analysis / Q000378:metabolism*; D010100:Oxygen / Q000032:analysis / Q000378:metabolism*; D011166:Porphyrins / Q000032:analysis / Q000378:metabolism*; D017433:Protein Structure, Secondary / Q000502:physiology; D011994:Recombinant Proteins / Q000032:analysis / Q000737:chemistry / Q000378:metabolism
chemical_list: D006420:Hemeproteins; D011166:Porphyrins; D011994:Recombinant Proteins; D007501:Iron; D043364:Endo-1,4-beta Xylanases; D010100:Oxygen