scholarly journals Biochemical characterization and thermal inactivation of polyphenol oxidase from elephant foot yam (Amorphophallus paeoniifolius)

2017 ◽  
Vol 54 (7) ◽  
pp. 2085-2093 ◽  
Author(s):  
Anuradha Singh ◽  
Neeraj Wadhwa
Keyword(s):  
Polyphenol Oxidase ◽  
Thermal Inactivation ◽  
Biochemical Characterization ◽  
Elephant Foot Yam

scholarly journals Purification and biochemical characterization of polyphenol oxidase from seeds of melon (Citrullus colocynthis)

2020 ◽  
Vol 19 (2) ◽  
pp. 223-231
Author(s):  
David Morakinyo Sanni ◽  
Catherine Joke Adeseko ◽  
Samuel Olufemi Bamidele
Keyword(s):  
Gallic Acid ◽  
Polyphenol Oxidase ◽  
Fruits And Vegetables ◽  
Biochemical Characterization ◽  
Apparent Molecular Weight ◽  
Citrullus Colocynthis ◽  
Effects Of Ph ◽  
Melon Seeds ◽  
Processing And Storage ◽  
Specificity Effects

Polyphenol oxidase (PPO) is an enzyme that is responsible for the enzymatic browning of fruits and vegetables. This is generally undesired process and need to be prevented in food technology. PPO from seeds of Citrullus colocynthis was purified, the physicochemical properties such as effects of pH and temperature, substrate specificity, effects of inhibitors and cations on PPO activity and the kinetic parameters for four substrates namely, catechol, L-DOPA, gallic acid and tyrosine, were determined. The purification steps resulted in 41-fold with 10 % yield, and the optima pH and temperature values for PPO from C. colocynthis were found to be pH 7.0 and 60 °C, respectively using catechol as substrate. About 9 % enzyme initial activity was retained after 60 min of incubation at 80 °C, and the apparent molecular weight was determined as 42 kDa by partially denaturing SDS-PAGE. PPO activity was inhibited by ascorbic acid, SDS and certain divalent (Ca2+, Zn2+, Mg2+ and, Fe2+) and monovalent (Na+) metal. Moreover, purified enzyme solution showed diphenolase activity toward catechol, gallic acid, L-DOPA and monophenolase activity toward tyrosine, therefore, tyrosinase was identified as the only one PPO in C. colocynthis seeds. This study revealed the use of temperature above 80 °C to inhibit PPO activity during processing and storage of melon seeds.

Purification and partial biochemical characterization of polyphenol oxidase from mamey (Pouteria sapota)

2011 ◽  
Vol 72 (1) ◽  
pp. 82-88 ◽  
Author(s):  
Gisela Palma-Orozco ◽  
Alicia Ortiz-Moreno ◽  
Lidia Dorantes-Álvarez ◽  
José G. Sampedro ◽  
Hugo Nájera
Keyword(s):  
Polyphenol Oxidase ◽  
Biochemical Characterization

Purification and Partial Biochemical Characterization of Polyphenol Oxidase from Mango (Mangifera indica cv. Manila)

2014 ◽  
Vol 62 (40) ◽  
pp. 9832-9840 ◽  
Author(s):  
Gisela Palma-Orozco ◽  
Norma A. Marrufo-Hernández ◽  
José G. Sampedro ◽  
Hugo Nájera
Keyword(s):  
Polyphenol Oxidase ◽  
Biochemical Characterization ◽  
Mangifera Indica

scholarly journals Molecular and biochemical characterization of the thermoactive family 1 pectate lyase from the hyperthermophilic bacterium Thermotoga maritima

2003 ◽  
Vol 370 (2) ◽  
pp. 651-659 ◽  
Author(s):  
Leon D. KLUSKENS ◽  
Gert-Jan W.M. van ALEBEEK ◽  
Alphons G.J. VORAGEN ◽  
Willem M. de VOS ◽  
John van der OOST
Keyword(s):  
Thermal Inactivation ◽  
Biochemical Characterization ◽  
Thermotoga Maritima ◽  
Pectate Lyase ◽  
Major Product ◽  
Degree Of Polymerization ◽  
Extracellular Medium ◽  
Native Form ◽  
Hyperthermophilic Bacterium

The ability of the hyperthermophilic bacterium Thermotoga maritima to grow on pectin as a sole carbon source coincides with the secretion of a pectate lyase A (PelA) in the extracellular medium. The pelA gene of T. maritima was functionally expressed in Escherichia coli as the first heterologously produced thermophilic pectinase, and purified to homogeneity. Gel filtration indicated that the native form of PelA is tetrameric. Highest activity (422units/mg, with a Km of 0.06mM) was demonstrated on polygalacturonic acid (PGA), whereas pectins with an increasing degree of methylation were degraded at a decreasing rate. In the tradition of pectate lyases, PelA demonstrated full dependency on Ca2+ for stability and activity. The enzyme is highly thermoactive and thermostable, operating optimally at 90°C and pH9.0, with a half-life for thermal inactivation of almost 2h at 95°C, and an apparent melting temperature of 102.5°C. Detailed characterization of the product formation with PGA indicated that PelA has a unique eliminative exo-cleavage pattern liberating unsaturated trigalacturonate as the major product, in contrast with unsaturated digalacturonate for other exopectate lyases known. The unique exo-acting mode of action was supported by progression profiles of PelA on oligogalacturonides (degree of polymerization, 3—8) and the examination of the bond cleavage frequencies.

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