title: Construction and Characterization of Vitreoscilla Hemoglobin (VHb) with Enhanced Peroxidase Activity for Efficient Degradation of Textile Dye.
abstract: Pollution resulting from the discharge of textile dyes into water systems has become a major global concern. Because peroxidases are known for their ability to decolorize and detoxify textile dyes, the peroxidase activity of Vitreoscilla hemoglobin (VHb) has recently been studied. It is found that VHb and variants of this enzyme show great promise for enzymatic decolorization of dyes and may play a role in achieving their successful removal from industrial wastewater. The level of VHb peroxidase activity correlates with two amino acid residues present within the conserved distal pocket, at positions 53 and 54. In this work, sitedirected mutagenesis of these residues was performed and resulted in improved VHb peroxidase activity. The double mutant, Q53H/P54C, shows the highest dye decolorization and removal efficiency, with 70% removal efficiency within 5 min. UV spectral studies of Q53H/P54C reveals a more compact structure and an altered porphyrin environment (λSoret = 413 nm) relative to that of wild-type VHb (λSoret = 406), and differential scanning calorimetry data indicate that the VHb variant protein structure is more stable. In addition, circular dichroism spectroscopic studies indicate that this variant's increased protein structural stability is due to an increase in helical structure, as deduced from the melting temperature, which is higher than 90°C. Therefore, the VHb variant Q53H/P54C shows promise as an excellent peroxidase, with excellent dye decolorization activity and a more stable structure than wild-type VHb under high-temperature conditions.
authors.affiliation: College of Wildlife Resource, Northeast Forestry University, Harbin 150040, P.R. China.|Key Laboratory for Molecular Enzymology & Engineering, The Ministry of Education, College of Life Science, Jilin University, ChangChun 130012, P.R. China.
authors.forename: Zidong
authors.initials: Z
authors.lastname: Zhang
authors.affiliation: Key Laboratory for Molecular Enzymology & Engineering, The Ministry of Education, College of Life Science, Jilin University, ChangChun 130012, P.R. China.
authors.forename: Wei
authors.initials: W
authors.lastname: Li
authors.affiliation: Key Laboratory for Molecular Enzymology & Engineering, The Ministry of Education, College of Life Science, Jilin University, ChangChun 130012, P.R. China.
authors.forename: Haichao
authors.initials: H
authors.lastname: Li
authors.affiliation: Key Laboratory for Molecular Enzymology & Engineering, The Ministry of Education, College of Life Science, Jilin University, ChangChun 130012, P.R. China.
authors.forename: Jing
authors.initials: J
authors.lastname: Zhang
authors.affiliation: Key Laboratory for Molecular Enzymology & Engineering, The Ministry of Education, College of Life Science, Jilin University, ChangChun 130012, P.R. China.
authors.forename: Yuebin
authors.initials: Y
authors.lastname: Zhang
authors.affiliation: Fundamental Nursing Department, Chang Chun Medical School, ChangChun 130031, P.R. China.
authors.forename: Yufeng
authors.initials: Y
authors.lastname: Cao
authors.affiliation: College of Wildlife Resource, Northeast Forestry University, Harbin 150040, P.R. China.
authors.forename: Jianzhang
authors.initials: J
authors.lastname: Ma
authors.affiliation: Key Laboratory for Molecular Enzymology & Engineering, The Ministry of Education, College of Life Science, Jilin University, ChangChun 130012, P.R. China.
authors.forename: Zhengqiang
authors.initials: Z
authors.lastname: Li
mesh_terms: D001426:Bacterial Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D001711:Biotransformation; D002152:Calorimetry, Differential Scanning; D002942:Circular Dichroism; D004396:Coloring Agents / Q000378:metabolism*; D004252:DNA Mutational Analysis; D016297:Mutagenesis, Site-Directed; D009195:Peroxidase / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D011487:Protein Conformation; D055550:Protein Stability; D013056:Spectrophotometry, Ultraviolet; D013696:Temperature; D054793:Truncated Hemoglobins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D014874:Water Pollutants, Chemical / Q000378:metabolism
chemical_list: D001426:Bacterial Proteins; D004396:Coloring Agents; D054793:Truncated Hemoglobins; D014874:Water Pollutants, Chemical; C082613:hemoglobin protein, Vitreoscilla; D009195:Peroxidase
keywords: Vitreoscilla hemoglobin; decolorization; dye; peroxidase activity