Hydrolysis by lipases

Effect of Molecular Weight of Polyester on the Hydrolysis by Rhizopus lipase. Using three kinds of polyesters, PCL-diol (I), polyhexameth-ylene adipate (II), and a copolyester (ill) made from 1,6-hexamethyl-enediol and a 70 30 molar ratio mixture of e- caprolactone and adipic acid, the effects of the of polyester on the hydrolysis by lipase were examined (Figure k) Mn did not affect the rates of hydrolysis by R. arrhizus and delemar lipases when Vln was more than about UOOO. This would indicate these lipases randomly splits ester bonds in pol-mer chains. In contrast, when TEi was less than about i4000 2 the rates of the enzymatic hydrolysis were faster with the smaller Mn of polyesters. This corresponded to the fact that Tm was lower with the smaller Mn of polyesters. 

Figure U. Effects of molecular weight of polyester on the hydrolysis by lipases. Three kinds of polyesters were used PCL-diol ( ), polyhexamethylene adipate (O ) and their copolyester ( ). The dashed line shows the result when one tenth enzyme concentration was used.

Based on the recent impressive progress made on asymmetric hydrolysis, the design and bio-transformation of the optically active ethyl 2,2-difluoro-3-hydroxyoctanoate 78 and synthesis of optically active fluorinated [6]-gingerol derivatives are reported [82]. The following criteria were used in the search for a practical route to chiral ethyl 2,2-difluoro-3-hydroxyoctanoate with a high -value (1) the search of an additive to enhance the enantioselectivity of asymmetric hydrolysis by lipases, and (2) the modification of ethyl 2,2-difluoro-... 

The meso-diol was enzymatically acetylated, which afforded the mono-acetate with 25,6/ - configuration. Hydrolysis by lipase reaction (PLE) gave an intermediate through which four reaction steps resulted in the N-protected (Cbz-group) ethyl ester, which could be finally transformed to the (—)-enantiomer of the target alkaloid (—) -gephyrotoxin. 

PCL was also degraded to 6-hydroxyhexanoic acid during enzymatic hydrolysis by Lipase Asahi derived from Chromobacterium viscosum and Hp-ase F derived from Rhizopus niveus [74]. In another study formation of oligomers during biotic hydrolysis of PCL was shown by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF) [50]. Enzymatic degradation of copolymers of 3-hydroxybutyric acid (3HB) and... 

Good and bad features of enzymes as catalysts Organisms Reduction of Ketones by Baker s Yeast Ester Formation and Hydrolysis by Lipases and Esterases... 

Fatty acids may be converted by fungi after hydrolysis by lipase. Other organic acid carbon sources would be oleic, linoleic and linolenic acids. These might also serve as foam control agents. Carbon dioxide is a possible carbon source in nature, but is not practical commercially due to low growth rates. 

Various bacterial, fungal and plant lipases have been described to hydrolyze PET (Table 15.1). Lipases catalyze the hydrolysis of long chain water insoluble triglycerides and, unlike cutinase they are interfacially activated in the presence of a water-lipid interface [63-65]. The active site of lipases is covered with a peptide segment called lid while upon opening the active site becomes accessible to the substrate. Consequently, it as been indicated that PET hydrolysis by lipase can be improved in the presence of detergents [55, 66]. Apart from typical lipases and cutinases, other esterases have been shown to hydrolyze PET. Nevertheless, it is not quite clear yet what constitues a PET-hydrolase. On the one hand a comprehensive comparison of all reported enzymes on typical lipase and cutinase substrates in addition to PET is not available. On the other hand, apart from the active site architecture and specificities on water soluble substrates, the adsorption behavior onto polymers will also play a major role. 

Examples for a high degree of promiscuity obviously include nonenzymatic proteins such as serum albumins that exhibit promiscuous catalytic activities (Table 1, entry 14). Other cases may include catalysis of unnatural reactions, meaning reactions for which, to our knowledge, no natural enzyme has evolved (e.g., the Kemp elimination performed by serum albumin (Table 1, entry 14, or siloxane hydrolysis by lipase (Table 1, entry 7)). 

The effect of pH on the rate of hydrolysis by lipase is a resultant of its effects not only on the enzyme itself, but also on the emulsified substrate and properties of die substrate aqueous phase interface. For mo.st lipases the pH optimum is on the alkaline side of neutrality, but some are most active in acid solution. The optimum pH often depends on the substrate used. 

Willstatter ef al. 196, 301) found that activation could be observed in an alkaline medium but not in an acid medium. Inhibition of tributyrin hydrolysis by bile salts at pH values below 7.0 was also observed by Click and King (297), and Wills (302) found that, although triolein hydrolysis by lipase was stimulated by sodium taurocholate in an alkaline medium, it was inhibited at pH values below 7.0. The effect of the bile salt may also depend on the length of fatty acid chain of the triglyceride under investigation. Thus Click and King (297) showed that, at pH 7.0, sodium taurocholate inhibited tributyrin hydrolysis but stimulated triolein hydrolysis. Similar results were obtained by Wills (302), who found that triacetin hydrolysis was inhibited and triolein hydrolysis stimulated by equivalent concentrations of sodium taurocholate. 

The type of enzyme to be used, and quantification of degradation, will depend on the polymer being screened. For example, Mochizukiet studied the effects of draw ratio of polycaprolactone (PCL) fibres on enzymatic hydrolysis by lipase. Degradability of PCL fibres was monitored... 

Belafi-Bako K, Dombi A, Szabo, Nagy E (1994), Triacylglycerol Hydrolysis by Lipase in a Flat Membrane Bioreactor , Biotec/ino/. Tech., 8,671-674. 

Rizzarelli et al. [23] synthesized a series of copolymers with units of butylene succinate (BSu) and butylene adipate (BA) with different composition. The copolymers were subjected to enzymatic hydrolysis by lipase (actually two different lipase enzymes, obtained from Mucor miehei or from Rhizopus arrhizus). The degradation products were water soluble. Thus, they were injected in an LC apparatus (the column was a Cl 8) coupled with an ESI-MS. The LC trace displayed more than 20 peaks that were easily identified using MS. These are due to the monomers (BSu and BA), the dimers, the trimers, and the tetramers. LC peaks due to the oligomers rich in BA (e.g., BA3) are weak. On the other hand, LC peaks due to the oligomers rich in BSu (e.g.,BSus) are strong. The results indicate a preferential hydrolytic cleavage. In particular, succinic ester bonds are hydrolyzed faster than adipic ester bonds in BSu-BA copolyesters. 

Knezevic, Z., L. Mojovic, and B. Adnadjevic. 1998. Palm Oil Hydrolysis by Lipase from Candida Cylindracea Immobilized on Zeolite Type Y. Enzyme and Microbial Technology 22 (4) 275-280. 

Typical biodegradants plasticizers are attacked by fungi hydrolysis by lipase Demenech-Carbo, M T Bifossi, G de la Cruz-Canizares, J Bolivar-Galiano, F del Mar Lopez-Miras, M Romero-Noguera, J Martin-Sanchez, 1, J. Anal. Appl. Pyrolysis, 85,480-86, 2009 Chattopadhyay, S SK/alingam, G Madias, G, Polym. Deg. Stab., 80, 477-83, 2003. 

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