Response surface methodological study on lipase-catalyzed synthesis of amino acid surfactants

Abstract

Lipozyme (Rhizomucor miehei lipase) was used to catalyze the acylation of the amino acid llysine (L) with the free fatty acids, palmitic (PA) and oleic (OA) acids, to synthesize N-εpalmitoyllysine and N-ε-oleoyllysine, respectively. Response surface methodology (RSM) based on a five-level, five-variable design was employed, firstly, for studying the interactive effects of various parameters on the reactions, and secondly, for their optimization. Simultaneously increasing temperature and solvent hydrophobicity, fatty substrate concentration or enzyme amount improved yields in both reactions, as did increasing solvent hydrophobicity and substrate concentration or enzyme amount, and substrate concentration and enzyme amount together. Increasing desiccant amount in very non-polar solvents, at very high levels of enzyme, and in very concentrated substrate solutions led to higher yields in the PA reaction but compromised the OA reaction. The optimum conditions predicted for the two reactions were: temperature, 69.3 •C (PA) and 56.6 •C (OA); solvent log P = 3.46 (PA) and log P = 3.50 (OA); fatty substrate concentration, 98.0mM (PA) and 99.9mM (OA); enzyme amount, 186 mg (PA and OA); molecular sieves, 160 mg (PA) and 80 mg (OA). Reactions under optimized conditions yielded 16.1% of N-ε-palmitoyllysine and 33.1% of N-εoleoyllysine.

Optimization of Palm-Based Wax Esters Production Using Statistical Experimental Designs

“…The coefficients of the empirical model and their statistical analyses are evaluated using Design Expert Software (22,23 …”

Development of novel thiolated carboxymethyl-gellan gum as potential mucoadhesive polymer: Application of DoE

“…In the present investigation, statistical design of experiments (DoE) was used which is generally employed for obtaining the largest possible amount of information about a system with the smallest number of experiments [33]. The classical method of chemical synthesis optimization involves varying one parameter at a time by keeping others constant; however this method is ineffective, as it fails to understand relationships between the variables and the responses [34,35]. By using DoE, degree of substitution (DS) was optimized in synthesis of N-carboxybutylchitosan and 1-allyloxy-2-hydroxy-propylstarch previously [36,37].…”

Application of Fuzzy Modeling and Optimization in Enzymatic Esterification Process

“…This result can also be seen in Figure 5(C) that shows the effect of varying enzyme amount and temperature on the synthesis of adipate ester at constant substrate molar ratio and time (0.563 and 0.536, respectively). At low amount of enzyme, the yield increases with increase in temperature that promotes acceleration in the rate of reaction [31]. Higher reaction temperatures cause enzyme inactivation due to denaturation process that can be compensated by using higher concentrations of enzyme.…”