Activity and Process Stability of Purified Green Pepper (Capsicum annuum) Pectin Methylesterase

Abstract

Pectin methylesterase (PME) from green bell peppers (Capsicum annuum) was extracted and purified by affinity chromatography on a CNBr-Sepharose-PMEI column. A single protein peak with pectin methylesterase activity was observed. For the pepper PME, a biochemical characterization in terms of molar mass (MM), isoelectric points (pI), and kinetic parameters for activity and thermostability was performed. The optimum pH for PME activity at 22°C was 7.5, and its optimum temperature at neutral pH was between 52.5 and 55.0°C. The purified pepper PME required the presence of 0.13 M NaCl for optimum activity. Isothermal inactivation of purified pepper PME in 20 mM Tris buffer (pH 7.5) could be described by a fractional conversion model for lower temperatures (55-57°C) and a biphasic model for higher temperatures (58-70°C). The enzyme showed a stable behavior toward high-pressure/temperature treatments.

Extraction and characterization of pectin methylesterase from Alyanak apricot (Prunus armeniaca L)

“…Karakus and Pekyardimci (2012) reported temperature optimum of free PME from Malatya apricot as 60°C which is in accord the one found in this study. Reported temperature optima for PMEs from different sources include 55°C for black carrot (Unal and Bellur 2009), 55°C for hawthorn (Vivar-Vera et al 2007), between 52.5 and 55.0 for green pepper (Castro et al 2004), 55°C for tomato (Van Den Broeck et al 2000), 65°C for plum (Prunus domestica) (Nunes et al 2006), which are similar to the one obtained in this study. However, higher temperature optima were reported for PME from guava, e.g.…”

“…In a study carried out by Karakus and Pekyardimci (2012) on comparison of covalent and noncovalent immobilization of pectinesterase isolated from Malatya apricot, it was found that the pH optima of covalently-immobilized and free PME were 8.0 and 9.0, respectively, which is slightly higher than the one found for Alyanak PME. Some of the reported optimum pH values for PME from different sources are 7.5 for black carrot (Daucus carota L.) (Unal and Bellur 2009), green pepper (Castro et al 2004), plum (Nunes et al 2006) and hawthorn (Vivar-Vera et al 2007), 8.0 for orange (Amaral et al 2005), 8.0 for peach (Javeri and Wicker 1991), 9.0 for guava (Carvalho et al 2009). The pH optimum of 7.5 found in this study was in accord with these values.…”

“…Na + dependence of PME varies depending on the enzyme source. The reported NaCl concentration for maximal PME activity include 0.13 M for green pepper (Castro et al 2004), 0.15 M for orange (Amaral et al 2005), 0.2 M for black carrot (Unal and Bellur 2009), 0.25 for kiwi, 0.3 M for guava (Carvalho et al 2009), 1.27 M for grapefruit (Guivarc'h et al 2005). …”

Activity of an atypical Arabidopsis thaliana pectin methylesterase

“…So far, most plant PMEs were found to be activated by NaCl. For example, a green ball pepper PME required 0.13 M NaCl for optimal activity at neutral pH or 0.4 M NaCl at acidic pH (Castro et al 2004). On the other hand, orange PME activity was not aVected by the increase in ionic strength (Savary et al 2002).…”

Simultaneous Modelling of the Thermal Degradation Kinetics of Pectin Methylesterase in Lettuce (Lactuca sativaL.) and Carrot (Daucus carotaL.) Extracts: Analysis of Seasonal Variation and Tissue Type

“…When working with purified PME, Nguyen et al 20,21) and Castro et al 22) have proposed a similar two fraction biexponential model for the mild thermal and highpressure inactivation kinetics of purified strawberry, carrot and green pepper pectin-esterase. Similar parameters between the models were found in all studies, leading to the hypothesis that the enzymes of different species might respond similarly to heat and pressure stresses.…”