Lipase activity of plant lattices from Apocynaceae species

TUPONE, M.L.; DI SANTO MEZTLER, P.; MORCELLE, S.R.

Congreso; Biotrans 2021; 2021

Biotrans

It is well known that lipases are among the most used enzymes in different industries, ranging frombiorefinery to pharma and food processing. Commercial enzymes are mainly of microbial origin.However, their cost is usually very high and, therefore, a cheaper alternative to lipases such asNovozym® 435 and Lipozyme® IM is of utmost interest [1]. Within this context, plant lipases represent a very attractive alternative, since extracts with lipolytic activity are relatively easy to obtain [2]. Latex is a fluid containing a mixture of compounds that plants use for defence when attacked by insects. Although its composition depends on plant species, different enzymes can be found in latex. Among them, lipases and esterases were detected in the most emblematic plant latex with enzymatic activity, Carica papaya latex. Similarly, lipolytic activity was found in other plant latices [3]. In this contribution, we report the biochemical characterization of lipolytic and esterification activity of the insoluble gums obtained from the latices of two species belonging to the Apocynaceae family, Araujia serificera (Fig. 1) and Calotropis procera (Fig. 2).Both Araujia serificera lipase and Calotropis procera lipase (ASL and CProL, respectively) showedhydrolytic activity with optimum pH in the alkaline range (8 to 12 for ASL and 9 to 11 for CProL).Esterification activity was tested using oleic acid (20 mM) and three alcohols (methanol, ethanol and n-butanol, 40 mM) in three different organic solvents (n-hexane, n-heptane and isooctane). After 1 h of reaction at 40 °C, the best conversions were observed using isooctane as cosolvent. Fig. 3 shows the preference for the alcohols. Both biocatalysts revealed the highest preference for methanol. CProL demonstrated a low affinity for n-butanol, whereas ethanol was the poorest nucleophile for ASL in this set of experiments. The active sites of ASL and CProL were explored by inhibition assays using tetrahydrolipstatin (THL), a lipase inhibitor that binds covalently to the Ser residue of the catalytic triad.The results showed that 1.2nmoles THL/mg of ASL and 0.6 nmoles THL/mg of CProL inhibited up to 67% of the hydrolytic activity of each biocatalystusing p-nitrophenol laurate as substrate. Similar behaviour was observed for other plant latex lipases [4, 5], making ASL and CProL interesting biocatalysts for further studies.References[1] E. Su J. Agriculture Food Chem., 2014, 62, 6375-6381.[2] E.D.C. Cavalcanti Appl. Biochem. Biotechnol., 2007, 136-140,57-65.[3] M. Mazou J. Appl. Biosci., 2017,110, 10790-10801.[4] R. Dhouib FEBS J., 2011, 278, 97-110.[5] S. Abdelkafi Biochim. Biophys. Acta, 2009, 1791, 1048-1056.Conversion (%)