Esters Aspergillus oryzae

Liu ZQ, Gosser Y, Baker PJ et al (2009) Stmctural and functional studies of Aspergillus oryzae cutinase enhanced thermostability and hydrolytic activity of synthetic ester and polyester degradation. J Am Chem Soc 131 15711-15716... 

Immobilisation of an Acetobacter aceti strain in calcium alginate resulted in improvement of the operational stability, substrate tolerance and specific activity of the cells and 23 g phenylacetic acid was produced within 9 days of fed-batch cultivation in an airlift bioreactor [133]. Lyophilised mycelia of Aspergillus oryzae and Rhizopus oryzae have been shown to efficiently catalyse ester formation with phenylacetic acid and phenylpropanoic acid and different short-chain alkanols in organic solvent media owing to their carboxylesterase activities [134, 135] (Scheme 23.8). For instance, in n-heptane with 35 mM acid and 70 mM alcohol, the formation of ethyl acetate and propylphenyl acetate was less effective (60 and 65% conversion yield) than if alcohols with increased chain lengths were used (1-butanol 85%, 3-methyl-l-butanol 86%, 1-pentanol 91%, 1-hexanol 100%). This effect was explained by a higher chemical affinity of the longer-chain alcohols, which are more hydrophobic, to the solvent. 

Four examples of structurally characterised, vanadate-inhibited phosphorylation enzymes working on the hydrolysis of phospho-ester bonds in nucleotides I, the vanadate-uridine complex of bovine pancreatic ribonuclease-A II, the vanadate complex of ribonuclease-Tj from the fungus Aspergillus oryzae-. III, the vanadate-uridine complex of cyclic nucleotide phosphodiesterase from the cruciferous plant Arabidopsis thaliana-, IV, human tyrosyl-DNA phosphodiesterase (Ur = uridine). 

The use of subtilisin (a protease which is widely used in detergent formulations) as a biocatalyst for the stereospecific hydrolysis of esters is well established [271-273]. Along the same lines, a protease derived from Aspergillus oryzae, which has hitherto mainly been used for cheese processing, has been shown to be particularly useful for the resolution of sterically hindered substrates such as a,a,a-trisubstituted carboxylates [274] (Scheme 2.42). While traditionaT proteases such as subtilisin were plagued by slow reaction rates and low selectivities, the a-tri-fluoromethyl mandelic ester (which constitutes a precursor of a widely used chiral derivatization agent, Mosher s acid [275]) was successfully resolved by Aspergillus oryzae protease [276]. 

Scheme 2.42 Resolutimi of bulky esters by subtilisin and Aspergillus oryzae protease...

Oligomeric PET model compounds have been widely used to study enzymatic hydrolysis of PET, since their degradation is faster and easier to analyze compared to a polymeric substrate. Diethyl terephthalate (DET), diethyl p-phthalate (DP), h/i(benzoyloxyethyl) terephthalate (PET trimer), ethylene glycol dibenzyl ester (BEB), and hA-(p-methylbenzoic acid)-ethylene glycol ester (PET dimer) have been employed (Eig. 2). Their degradation by PET hydrolases from Fusarium solani [27, 38], T. insolens [1, 5, 48, 101], P. mendocina [25, 49], T. fusca [26, 27, 38], Burkholderia cepacia [26, 27, 38], Aspergillus oryzae [103], Bacillus spp. [87], and porcine liver esterase [109, 110] has been reported, and the corresponding hydrolysis products have been partially characterized (Table 1). 

Several authors investigated the effects of lipases on chitosan and chitin degradation [44, 53, 61, 62], but lipases these authors used were in crude form and it has not been determined whether these lipases were able to split both carboxyl ester bonds in acyl glycerol and (3-1,4-glycosidic linkages in chitosan. In a previous study, we found that a commercial lipase preparation from Aspergillus oryzae could hydrolyze chitosan effectively [48],... 

Table 11.1-15. Lipase-catalyzed enantiomer-differentiating hydrolysis of esters of racemic acyclic secondary alcohols in aqueous solution (CCL Candida cylindracea lipase, PSL Pseudomonas sp. lipase, PFL Pseudomonas fluorescens lipase, PAL Pseudomonas aeruginosa lipase, ASL Alcaligenes sp. lipase, ANL Aspergillus niger lipase, PCL Pseudomonas cepacia lipase, ROL Rhizopus oryzae lipase,...

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