title: Encapsulation of hemoglobin in mesoporous silica (FSM)-enhanced thermal stability and resistance to denaturants.
abstract: Hemoblogin (Hb), which is a typical oligomeric protein, was introduced into the pores of mesoporous silica (FSM: folded-sheet mesoporous material) that had a diameter of 7.5 nm. Soret CD spectra of Hb-FSM-7.5 conjugates showed a peak that was identical to that of free Hb. This suggests that Hb retained its highly ordered structure in the mesoporous silica. In addition, the UV-visible absorption spectrum showed that Hb had an increased resistance to heat denaturation in the silica. Even after heat treatment at 85 degrees C, Hb-FSM-7.5 retained its ligand-binding activity. The stability of Hb-FSM-7.5 was examined further by measuring its peroxidase-like activity. Encapsulation of Hb resulted in the retention of activity in the presence of high NaCl or Gdn-HCl levels. This suggests that encapsulation prevented dissociation and denaturing. Thus, it seems that the mesopores created a favorable environment for the oligomeric protein to perform its function, even under harsh conditions.
authors.affiliation: Department of Applied Biological Science, Faculty of Science and Technology, Tokyo University of Science, 2641 Yamazaki, Noda, Chiba 278-8510, Japan.
authors.forename: Yoko
authors.initials: Y
authors.lastname: Urabe
authors.forename: Toru
authors.initials: T
authors.lastname: Shiomi
authors.forename: Tetsuji
authors.initials: T
authors.lastname: Itoh
authors.forename: Akiko
authors.initials: A
authors.lastname: Kawai
authors.forename: Tatsuo
authors.initials: T
authors.lastname: Tsunoda
authors.forename: Fujio
authors.initials: F
authors.lastname: Mizukami
authors.forename: Kengo
authors.initials: K
authors.lastname: Sakaguchi
mesh_terms: D001665:Binding Sites; D055598:Chemical Phenomena; D002627:Chemistry, Physical; D002942:Circular Dichroism; D004339:Drug Compounding; D006454:Hemoglobins / Q000737:chemistry*; D006358:Hot Temperature; D007501:Iron / Q000737:chemistry; D008024:Ligands; D008706:Methemoglobin / Q000737:chemistry; D010544:Peroxidases / Q000737:chemistry; D016062:Porosity; D011489:Protein Denaturation; D012822:Silicon Dioxide / Q000737:chemistry*; D013056:Spectrophotometry, Ultraviolet; D013816:Thermodynamics
chemical_list: D006454:Hemoglobins; D008024:Ligands; D012822:Silicon Dioxide; D008706:Methemoglobin; D007501:Iron; D010544:Peroxidases