Chemistry: molecular biology and microbiology – Micro-organism – tissue cell culture or enzyme using process... – Enzymatic production of a protein or polypeptide
Patent
1993-07-16
1996-06-04
Wityshyn, Michael G.
Chemistry: molecular biology and microbiology
Micro-organism, tissue cell culture or enzyme using process...
Enzymatic production of a protein or polypeptide
435219, 435222, 435220, 435221, 426 34, 426 41, 426656, 426657, C12P 2106, C12N 950, A23C 912
Patent
active
055232370
DESCRIPTION:
BRIEF SUMMARY
FIELD OF INVENTION
The present invention relates to a method for increasing the viscosity of a reaction mixture, plastein materials obtained by this method, and food products comprising these plastein materials.
BACKGROUND OF THE INVENTION
Non-bitter protein preparations are obtainable by performing a reversed hydrolysis. Proteolytic enzymic reactions are reversible as are other enzymic reactions. A reversal of the enzymic degradation of peptide bonds is termed a plastein reaction, and a protein-like product synthesized by a plastein reaction is termed plastein or plastein material [vide e.g. Horowitz, J. & Haurowitz, F. (1959); Biochim. Biophys. Acta., 33, 231-237; and Determann et al. (1963); Helv. Chim. Acta., 46, 2498]. Plastein material is different from protein and may be regarded as a mixture of high molecular polypeptides. In fact Wieland et al. [Wieland, T; Determann, H. & s Albrecht, E. (1960); Ann., 633, 185 ] define plastein reaction as the formation of high molecular polypeptides.
Various microbial proteases are known to posses plastein synthetic activities. Well known proteases also known for their plastein synthetic activities are pepsin, .alpha.-chymotrypsin, trypsin, and papain [vide e.g. Fujimaki, M.; Kato, H.; Arai, S. & Yamashita, M. (1971); J. Appl. Bact. 34(1), 119-131].
At least four points are hitherto believed to be complied with for the plastein reaction to proceed effectively. First, the concentration of substrate should be high. Second, the substrate should be of low molecular weight. Third, the pH for synthesis of the plastein is different than for hydrolysis of the protein. The pH range for synthesis of plastein is narrower than the pH range for hydrolysis. Fourth, a relatively long incubation time should be applied with.
Apart from removing bitterness of hydrolysates, the plastein reaction has other food processing potentials, e.g. preparing gel-like products with excellent visco-elastic properties for incorporation in different types of foods, preparing products with improved amino acid composition using mixtures of hydrolysates as substrates, preparing products with very high level of a single amino acid which could be used as a dietary supplement to certain foods, and preparing special types of soluble peptides having important flavour or other characteristics.
SUMMARY OF THE INVENTION
The present invention provides a method for increasing the viscosity of the reaction mixture, in which an enzyme preparation comprising a proteolytic enzyme having the following characteristics: acid (Asp) residues; gram of enzyme protein; phenylmethane sulfonylfluoride; 6.5-10.0; activity, is added to a proteinaceous substrate allowing a plastein reaction, followed by incubation at conditions at which increased viscosity occurs, and subsequent inactivation of the enzyme.
In its second aspect the invention provides plastein materials obtained by adding to a proteinaceous material an enzyme preparation comprising a proteolytic enzyme having the following characteristics: acid (Asp) residues; gram of enzyme protein; phenylmethane sulfonylfluoride; 6.5-10.0; activity, followed by incubation and subsequent inactivation of the enzyme.
In its third aspect the invention provides food products comprising plastein material of the invention.
The proteolytic enzyme defined above has previously been characterized in U.S. Pat. No. 4,266,031 as a contaminant of subtilisin A produced by Bacillus licheniformis. In this specification, however, the enzyme was wrongly characterised as a non-serine protease. Later investigations on this subject have now revealed that the enzyme is in fact inhibited by diisopropyl phosphofluoridate (DFP), and is therefore a serine protease.
Furthermore, there is no indication of the specific proteolytic activity of the enzyme in the above-mentioned US patent, and its utility for use in a process of the invention for increasing the viscosity of the reaction mixture is therefore not anticipated by the disclosure of the enzyme per se in this patent.
In International Patent A
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Budtz Peter
Nielsen Per M.
Agris Cheryl H.
Lankford L. Blaine
Novo Nordisk A S
Wityshyn Michael G.
Zelson Steve T.
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