title: Stability and structural changes of horseradish peroxidase: microwave versus conventional heating treatment.
abstract: Effects of conventional heating (CH) and microwave (MW) on the structure and activity of horseradish peroxidase (HRP) in buffer solution were studied. CH incubation between 30 and 45 °C increased activity of HRP, reaching 170% of residual activity (RA) after 4-6 h at 45 °C. CH treatment at 50 and 60 °C caused HRP inactivation: RA was 5.7 and 16.7% after 12 h, respectively. Secondary and tertiary HRP structural changes were analyzed by circular dichroism (CD) and intrinsic fluorescence emission, respectively. Under CH, activation of the enzyme was attributed to conformational changes in secondary and tertiary structures. MW treatment had significant effects on the residual activity of HRP. MW treatment at 45 °C/30W followed by CH treatment 45 °C regenerated the enzyme activity. The greatest loss in activity occurred at 60 °C/60 W/30 min (RA 16.9%); without recovery of the original activity. The inactivation of MW-treated HRP was related to the loss of tertiary structure, indicating changes around the tryptophan environment.
authors: Programa de Pós-Graduação em Biotecnologia Industrial, Universidade Tiradentes, Instituto de Tecnologia e Pesquisa. Laboratório de Engenharia de Bioprocessos, Av. Murilo Dantas, 300, Farolândia, 49032-490 Aracaju, SE, Brazil.
authors: Lucas C
authors: LC
authors: Lopes
authors: Programa de Pós-Graduação em Biotecnologia Industrial, Universidade Tiradentes, Instituto de Tecnologia e Pesquisa. Laboratório de Engenharia de Bioprocessos, Av. Murilo Dantas, 300, Farolândia, 49032-490 Aracaju, SE, Brazil.
authors: Maria T M
authors: MT
authors: Barreto
authors: Departamento de Biotecnologia Farmacêutica, Faculdade de Farmácia, Universidade Federal do Rio de Janeiro, Rio de Janeiro, RJ 21941-902, Brazil.
authors: Karen M
authors: KM
authors: Gonçalves
authors: Departamento de Ciências Exatas, Universidade Estadual de Feira de Santana, Km 03 BR 116, 44031-460 Feira de Santana, BA, Brazil.
authors: Heiddy M
authors: HM
authors: Alvarez
authors: Programa de Pós-Graduação em Biotecnologia Industrial, Universidade Tiradentes, Instituto de Tecnologia e Pesquisa. Laboratório de Engenharia de Bioprocessos, Av. Murilo Dantas, 300, Farolândia, 49032-490 Aracaju, SE, Brazil.
authors: Montserrat Fortuny
authors: MF
authors: Heredia
authors: Instituto de Química, Departamento de Química Orgânica, Biocatalysis and Organic Synthesis Group, Universidade Federal do Rio de Janeiro, Ilha do Fundão, Rio de Janeiro, RJ, Brazil.
authors: Rodrigo Octavio M A
authors: RO
authors: de Souza
authors: Departamento de Biotecnologia Farmacêutica, Faculdade de Farmácia, Universidade Federal do Rio de Janeiro, Rio de Janeiro, RJ 21941-902, Brazil.
authors: Yraima
authors: Y
authors: Cordeiro
authors: Programa de Pós-Graduação em Biotecnologia Industrial, Universidade Tiradentes, Instituto de Tecnologia e Pesquisa. Laboratório de Engenharia de Bioprocessos, Av. Murilo Dantas, 300, Farolândia, 49032-490 Aracaju, SE, Brazil.
authors: Cláudio
authors: C
authors: Dariva
authors: Programa de Pós-Graduação em Biotecnologia Industrial, Universidade Tiradentes, Instituto de Tecnologia e Pesquisa. Laboratório de Engenharia de Bioprocessos, Av. Murilo Dantas, 300, Farolândia, 49032-490 Aracaju, SE, Brazil. Electronic address: alinitf@yahoo.com.br.
authors: Alini T
authors: AT
authors: Fricks
mesh_terms: D002942:Circular Dichroism; D004795:Enzyme Stability; D006735:Horseradish Peroxidase / Q000037:antagonists & inhibitors / Q000737:chemistry* / Q000378:metabolism; D006358:Hot Temperature; D008872:Microwaves; D017433:Protein Structure, Secondary; D017434:Protein Structure, Tertiary; D014364:Tryptophan / Q000737:chemistry
chemical_list: D014364:Tryptophan; D006735:Horseradish Peroxidase
keywords: Conventional heating; Far UV-circular dichroism; Horseradish peroxidase; Microwave; Residual activity; Tryptophan fluorescence spectroscopy