title: A new peroxidase from leaves of guinea grass (Panicum maximum): A potential biocatalyst to build amperometric biosensors.
abstract: A new plant peroxidase was isolated from the leaves of guinea grass (Panicum maximum) and partially purified using a biphasic polymer system (poly(ethylene glycol) - ammonium sulfate) followed by size-exclusion chromatography and ultracentrifugation until obtaining a homogeneous extract containing a high peroxidase activity. The novel peroxidase was characterized as having a specific activity of 408U/mg and a molecular weight of 30kDa. The pH for its optimum activity was 8.0 and exhibited a high thermostability at 66°C with a kinactof 8.0×10-3min-1. The best substrates for peroxidase from guinea grass are o-dianisidine and 2,2'-azino-bis-(3-ethylbenzthiazoline-6-sulfonic acid). POD from guinea grass was directly immobilized on the surface of a graphene screen printed electrode and cyclic voltammograms in the presence of potassium ferrocyanide ([Fe(CN)6]3-/4-) as a redox species demonstrated an increase in the electron transfer process. The graphene- modified electrode exhibits excellent electrocatalytic activity to the reduction of H2O2, with a linear response in the 100μM to 3.5mM concentration range and a detection limit of 150μM. The new peroxidase from guinea grass allowed the modification of a graphene electrode providing a potential sensor detection system for determination of H2O2in real samples with some biomedical or environmental importance.
authors.affiliation: Grupo de Investigación en Bioquímica y Microbiología, GIBIM, Universidad Industrial de Santander, Bucaramanga, Colombia.
authors.forename: Diana A
authors.initials: DA
authors.lastname: Centeno
authors.affiliation: Grupo de Investigación en Bioquímica y Microbiología, GIBIM, Universidad Industrial de Santander, Bucaramanga, Colombia.
authors.forename: Xuxan H
authors.initials: XH
authors.lastname: Solano
authors.affiliation: Grupo de Investigación en Bioquímica y Microbiología, GIBIM, Universidad Industrial de Santander, Bucaramanga, Colombia. Electronic address: jcasleon@uis.edu.co.
authors.forename: John J
authors.initials: JJ
authors.lastname: Castillo
mesh_terms: D015374:Biosensing Techniques / Q000379:methods*; D004563:Electrochemistry; D004795:Enzyme Stability; D006108:Graphite / Q000737:chemistry; D006861:Hydrogen Peroxide / Q000032:analysis / Q000737:chemistry; D057230:Limit of Detection; D008897:Panicum / Q000201:enzymology*; D009195:Peroxidase / Q000737:chemistry / Q000378:metabolism*; D018515:Plant Leaves / Q000201:enzymology*; D013379:Substrate Specificity
chemical_list: D006108:Graphite; D006861:Hydrogen Peroxide; D009195:Peroxidase
keywords: Biosensor; Graphene; Guinea grass; Hydrogen peroxide; Peroxidase