Purification, characterization, and application of an acid urease from

Miyagawa, Katsuro; Sumida, Motoo; Nakao, Masahiro; Harada, Masami; Yamamoto, Hiroshi; Kusumi, Takenori; Yoshizawa, Kiyoshi; Amachi, Teruo; Nakayama, Tôru

doi:10.1016/s0168-1656(98)00210-7

Cited by 56 publications

(22 citation statements)

References 25 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…To overcome this problem purified acid urease from Lactobacillus fermentum are now commercially available and utilized in wines and fermented beverages production (Fidaleo et al, 2006;and references cited therein). For example, the addition of acid urease from crude extract to unrefined Japanese sake (20% (v/v) ethanol) containing 35 mg/L urea reduced its concentration to undetectable levels (Miyagawa et al,1999). Ough et al have demonstrated the effect of dead cells of L. fermentum on the urea levels in wine (Ough et al, 1991).…”

Section: Preventing Actions and Related Environmental Issuesmentioning

confidence: 99%

Ethyl Carbamate in Foods and Beverages – A Review

Weber

Шарыпов

2009

Climate Change, Intercropping, Pest Control and Beneficial Microorganisms

View full text Add to dashboard Cite

Foods and beverages contain many toxic chemicals that raise health concerns. Ethyl carbamate (EC) or urethane is the ethyl ester of carbamic acid. It occurs at low levels, from ng/L to mg/L, in many fermented foods and beverages. EC is genotoxic and carcinogenic for a number of species such as mice, rats, hamsters and monkeys. It has been classified as a group 2A carcinogen, "probably carcinogenic to humans", by the World Health Organization's International Agency for Research on Cancer (IARC) in 2007. The benchmark dose lower limit of EC is 0.3 mg/kg bw/day and the mean intake of EC from food is approximately 15 ng/kg bw/day. Those levels were calculated for relevant foods including bread, fermented milk products and soy sauce. Alcoholic beverages were not included in this calculation. However, high levels of EC can be found in distilled spirits at concentrations ranging from 0.01 mg/L to 12 mg/L depending on to the origin of spirit. Alcoholic drinks should thus be considered as a source of EC. EC is produced by several chemical mechanisms: first, from urea and various proteins like citrulline produced during the fermentation step, and second from cyanide and hydrocyanic acid, via EC precursors such as cyanate. A large panel of EC formation mechanisms is described from simple ethanolysis of urea in homogeneous liquid phase to photochemical oxidation of cyanide ion or complex heterogeneous gas/solid catalytic reactions. Determination of EC in foods and beverages involves various strategies according to the material, food or beverage, solid or liquid, and according to the concentration, from ng/L to mg/L. Usually adapted extractive techniques and pre-concentration steps are followed by analysis by gas chromatography coupled to mass spectrometry (GC-MS of GC-MS-MS). High-performance liquid chromatography (HPLC) and semi-quantitative spectroscopic methods (infra-red) are also proposed as valuable alternatives to the classical but time-consuming GC-MS. Various preventing methods are developed and used in some cases at industrial scale to lower EC levels in food. Two types of preventing methods are described. practices in all steps of the chain of food (or beverages) production lead, in general, to low EC level. Secondly, the abatement of EC precursors can be done by adapted enzymatic, physical-chemical or chemical methods according to the nature of raw materials and conditions of their production processes.

show abstract

Section: Preventing Actions and Related Environmental Issuesmentioning

confidence: 99%

Ethyl Carbamate in Foods and Beverages – A Review

Weber

Шарыпов

2009

Climate Change, Intercropping, Pest Control and Beneficial Microorganisms

View full text Add to dashboard Cite

show abstract

“…However, this method produces excess ammonium that could affect the wine taste. Alternatively, the addition of acid urease can efficiently eliminate urea in wine and repress EC formation indirectly (11), but the utilization of urease is restricted because of its special requirement of nickel ions, which are harmful to humans (12). Therefore, it is necessary to find a safe and effective method to minimize the formation of EC.…”

mentioning

confidence: 99%

Metabolic Engineering of the Regulators in Nitrogen Catabolite Repression To Reduce the Production of Ethyl Carbamate in a Model Rice Wine System

Zhao

Zhang

et al. 2014

Appl Environ Microbiol

View full text Add to dashboard Cite

Rice wine has been one of the most popular traditional alcoholic drinks in China. However, the presence of potentially carcinogenic ethyl carbamate (EC) in rice wine has raised a series of food safety issues. During rice wine production, the key reason for EC formation is urea accumulation, which occurs because of nitrogen catabolite repression (NCR) in Saccharomyces cerevisiae. NCR represses urea utilization by retaining Gln3p in the cytoplasm when preferred nitrogen sources are present. In order to increase the nuclear localization of Gln3p, some possible phosphorylation sites on the nuclear localization signal were mutated and the nuclear localization regulation signal was truncated, and the disruption of URE2 provided an additional method of reducing urea accumulation. By combining these strategies, the genes involved in urea utilization (DUR1,2 and DUR3) could be significantly activated in the presence of glutamine. During shake flask fermentations of the genetically modified strains, very little urea accumulated in the medium. Furthermore, the concentrations of urea and EC were reduced by 63% and 72%, respectively, in a model rice wine system. Examination of the normal nutrients in rice wine indicated that there were few differences in fermentation characteristics between the wild-type strain and the genetically modified strain. These results show that metabolic engineering of the NCR regulators has great potential as a method for eliminating EC during rice wine production.

show abstract

“…Jack bean urease, which is the most widely used plant urease, is a nickel containing oligomeric enzyme exhibiting a high degree of specifity to urea [2]. The importance and applications of the urease as a good catalyst for hydrolysis of urea have attracted several research interests [3][4][5][6][7][8][9][10][11][12][13][14][15] especially in biotechnology and biomedical engineering. Also, the thermostability of jack bean urease has often been a subject of investigations [14].…”

Section: Introductionmentioning

confidence: 99%

Application of Daftardar-Gejiji and Jafari Method to kinetic analysis of thermal inactivation of Jack Bean Urease

Sobamowo¹,

Adeleye²

2018

J. Appl. Math. Comput. Mech.

View full text Add to dashboard Cite

Abstract. Jack bean urease has been used as a good catalyst for hydrolysis of urea in various applications such as biotechnology and biomedical engineering. The wide range of applications require proper understanding of the thermal inactivation of the enzyme. Consequently, the theoretical analysis of the enzyme kinetic of the thermal inactivation is required. In this paper, a new iterative method proposed by Daftardar-Gejiji and the Jafari method is applied to analyse the kinetic of thermal inactivation of jack bean urease (EC3.5.1.5). The kinetics of the urease consist of three-reaction steps and included the Arrhenius equation for temperature-dependent rate constants as well as the temperature change in the initial heating period. The approximate analytical solutions are verified with results of numerical method using Runge-Kutta with the shooting method, and good agreements are established between the results of the methods. From the analytical investigation, it is established that the molar concentration of the native enzyme decreases as the time increases while the molar concentration of the denatured enzyme increases as the time increases. The time taken to reach the maximum value of the molar concentration of the native enzyme is the same as the time taken to reach the minimum value of the molar concentration of the denature enzyme. It is hoped that the information given in this theoretical investigation will assist in the kinetic analysis of thermal inactivation of the experimental results over handling rate constants and molar concentrations. MSC 2010: 35A15

show abstract

Purification, characterization, and application of an acid urease from

Cited by 56 publications

References 25 publications

Ethyl Carbamate in Foods and Beverages – A Review

Ethyl Carbamate in Foods and Beverages – A Review

Metabolic Engineering of the Regulators in Nitrogen Catabolite Repression To Reduce the Production of Ethyl Carbamate in a Model Rice Wine System

Application of Daftardar-Gejiji and Jafari Method to kinetic analysis of thermal inactivation of Jack Bean Urease

Contact Info

Product

Resources

About