Aspergillus oryzae acid

Penicillopepsin Aspergillopeptidase A Aspergillus oryzae acid protease Rhizopus-pepsin Mucor rennins... 

An alternative to extraction crystallization is used to obtain a desired enantiomer after asymmetric hydrolysis by Evonik Industries. In such a way, L-amino acids for infusion solutions or as intermediates for pharmaceuticals are prepared [35,36]. For example, non-proteinogenic amino acids like L-norvaline or L-norleucine are possible products. The racemic A-acteyl-amino acid is converted by acylase 1 from Aspergillus oryzae to yield the enantiopure L-amino acid, acetic acid and the unconverted substrate (Figure 4.7). The product recovery is achieved by crystallization, benefiting from the low solubility of the product. The product mixture is filtrated by an ultrafiltration membrane and the unconverted acetyl-amino acid is reracemized in a subsequent step. The product yield is 80% and the enantiomeric excess 99.5%. 

Kojic acid was first reported by Saito,2 who isolated it as a crystalline substance from the mycelia of Aspergillus oryzae grown on steamed rice. Yabuta coined the name of the compound (from koji = steamed rice), and by systematic study3 4 gathered enough evidence to propose two... 

Following Mosher s report, several publications appeared showing the preparation of Mosher s acid. One example is the chemoenzymatic preparation of Mosher s acid using Aspergillus oryzae protease (Scheme 1-5)24 ... 

Aspergillus oryzae protease Scheme 1-5. Chemoenzymatic preparation of Mosher s acid. 

The amylase of Aspergillus oryzae is most active in slightly acid solutions. When reacting in the presence of 0.01 M acetate at 40° it is most active71 at pH 5.0. 

Feruloyl esterase activity was first detected in culture filtrates of Strepto-myces olivochromogenes (49), and has thereafter also been reported for some hemicellulolytic fungi (Table III). A partially purified feruloyl esterase from S. commune liberated hardly any ferulic acid without the presence of xylanase (65). Very recently a feruloyl esterase was purified from Aspergillus oryzae (Tenkanen, M. Schuseil, J. Puls, J. Poutanen, K., /. Biotechnol, in press). The enzyme is an acidic monomeric protein having an isoelectric point of 3.6 and a molecular weight of 30 kDa. It has wide substrate specificity, liberating ferulic, p-coumaric, and acetic acids from steam-extracted wheat straw arabinoxylan. 

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. 

Several of the pyran-4-ones found in nature are acidic by virtue of carboxylic acid or hydroxyl groups. Chelidonic (346), meconic (347), comenic (348) and pyromeconic (349) acids and maltol (350) are of plant origin but kojic acid (351) is produced by microorganisms, for example Aspergillus oryzae. Several compounds of this type are used to enhance the flavor of foods. The pyran-4-ones are more basic than their isomeric pyran-2-ones and this results in the formation of more stable salts with acids such as perchloric acid. 

Hydroxypyran-4-ones are potent flavouring materials of which maltol (427), present in roasted malt, is particularly well known. Amongst other features, it imparts a newly baked odour to bread. Kojic acid (712) is produced in an aerobic process by a range of microorganisms, notably Aspergillus oryzae, from a variety of carbohydrate sources and is used as a source of maltol. 

Acylase (acylase I aminoacylase N-acetyl amino acid amidohydrolase E.C. 3.5.1.14), is one of the best-known enzymes as far as substrate specificity (Chenault, 1989) or use in immobilized (Takahashi, 1989) or membrane reactors (Wandrey, 1977, 1979 Leuchtenberger, 1984 Bommarius, 1992a) is concerned however, its exact mechanism or 3D structure is still not known (Gentzen, 1979 1980). Acylase is available in large, process-scale quantities from two sources, porcine kidney and the mold Aspergillus oryzae. 

Aspergillus oryzae protyrosinase (pro-TY) is a homotetramer composed of 60 kDa subunits containing 2 mol of copper per mol of subunit [139], The proenzyme is inactive at neutral pH, and is activated under conditions of acidic pH [138], The acid activation is quite unique mechanism for activation of a protyrosinase. To investigate the mechanism of acid activation, and the conformational change following the shift of pH and interactions between the subunits were examined (159). 

Tatara, Y., Namba, T., Yamagata, Y., Yoshida, T., Uchida, T., and Ichishima, E. (2008). Acid activation of protyrosinase from Aspergillus oryzae homo-tetrameric protyrosinase is converted to active dimmers with an essential intersubunit disulfide bond at acidic pH. Pigment Cell Melanoma Res., 21, 89-96. 

Kato, Y. and Matsuda, K. (1980) Structure of oligosaccharides obtained by controlled degradation of mung bean xyloglucan with acid and Aspergillus oryzae enzyme preparation. Agric Biol Chem 44,1751-1758... 

Figure 7.12 Identification of the amino acid residues involved in the seven subsite binding of the substrate in the active-site of Aspergillus oryzae a-amylase. The bold faced amino acid residues are those conserved in the active-site of porcine pancreatic a-amylase. (From Matsuura et al. 123 reprinted by permission)...

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