Comparison of the Lipase Activity in Hydrolysis and Acyl Transfer Reactions of Two Latex Plant Extracts from Babaco (Vasconcellea × Heilbornii Cv.) and Plumeria rubra:  Effect of the Aqueous Microenvironment

Abstract

The enzymatic properties of Plumeria rubra latex have been evaluated for the first time, showing a high activity in both hydrolysis and synthesis reactions, and compared to the biocatalytic behavior of babaco (Vasconcellea x Heilbornii cv.) latex. Both biocatalysts have been optimized by studying the various parameters that influence reaction kinetics. The optimum temperatures for hydrolysis reactions were 50 and 55 degrees C for babaco and Plumeria, respectively. The optimum pH for babaco latex was 7, whereas for Plumeria latex, two optimal pH values (4 and 7) were observed. With regard to esterification and acyl transfer reactions such as alcoholysis and interesterification, the influence of thermodynamic water activity on reaction yields was determined and correlated with water sorption and desorption isotherms. When babaco latex is used as a biocatalyst, optimal synthesis reaction yields are obtained when the enzymatic extract is stabilized at a water activity value of 0.38, which corresponds to a water content of 5.7%. This optimal level of hydration is located on the linear portion of the biocatalyst's sorption isotherm, where the water molecules exhibit high-energy interactions with the protein network. In synthesis reactions (esterification, alcoholysis, and interesterification) biocatalyzed by Plumeria latex, correlation between best reaction yields and water activity cannot be done. Indeed, the sorption isotherm plot has an atypical shape, indicating that water might be trapped in the latex matrix and, consequently, that the water content of the biocatalyst is highly dependent on the hydration history of the latex.

Reactivity of Dinuclear Copper(II) Complexes with N‐Salicylidene Glycine Schiff Bases as Carboxylesterase Models

“…Besides other factors (e.g., temperature, catalyst concentration, substrate concentration), pH is also an important influencing factor in the stability of enzymes. Extremely low or high pH values probably result in complete or partial deactivation for most enzymes . In our study, k ob –pH profiles in Fig.…”

Plumeria rubra L. (Apocynaceae): Ethnobotany, Phytochemistry and Pharmacology: A Mini Review

“…The biocatalytic activity in terms of lipase activity in hydrolysis and acyl transfer reactions of latex was compared with that of babaco (Vasconcellea x Heilbornii Cv.) (Cambon et al, 2006). Six compounds such as four iridoids, fulvoplumierin, allamcin, allamandin and plumericin; 2,5-dimethoxy-p-benzoquinone and lignan liriodendrin were isolated from different extracts of the plants all showing toxicity to murine lymphocytic leukemia and various human cancer cell-lines (breast, colon, melanoma, lung, fibrosarcoma, KB) (Kardono et al, 1990).…”

Characterization of typo-, regio-, and stereo-selectivities of babaco latex lipase in aqueous and organic media

“…Carica pentagona), native to the subtropical mountains of Equator, contains a latex similar to that found in Carica papaya (Kyndt et al 2005). In previous studies, its latex was shown to exhibit biocatalytic activities and the effect of the aqueous microenvironment on the synthesis activity has been evaluated (Cambon et al 2006). In this work, the typo-, regioand stereo-selectivities of crude babaco latex lipase were studied in both aqueous and organic solvents, in hydrolysis and acyltransfer reactions, and compared to those of papaya latex.…”