Enzymes suppliers

Thus a number of enzymes have been shown to be able to control the oxidation of sulfides to optically active sulfoxides most extensive investigations have concentrated on mono-oxygenases (e.g. from Acinetobacter sp., Pseudomonas putida) and haloperoxidases1 071 (from Caldariomyces fumago and Coral I ina officinalis). A comparison of the methodologies11081 led to the conclusion that the haloperoxidase method was more convenient since the catalysts are more readily available (from enzyme suppliers), the oxidant (H2O2) is cheap and no cofactor recycling is necessary with the haloperoxidases. Typical examples of haloperoxidase-catalysed reactions are described in Scheme 24. 

Until the end of the sixties enzyme products such as the detergent proteases were just powder products. Today very few powdered-enzyme products remain. All detergent enzyme products from the larger enzyme suppliers arc either hquid formulations or granulated and further protected by coatings. Today formulation techniques really have become a science with MAC-values in production facilities of 10-100 nanogram/m air. It is further recommended that the use of such safe enzyme products shall be planned such that the liquid enzyme product is not spilled and allowed to diy and aerosol formation shall be prevented. With these simple rules in mind, industrial enzymes arc very safe. 

Enzyme suppliers determine the activity of their products by measuring the extent of the catalysed reaction under carefully controlled conditions. A standard test exists for amylases (AATCC Test Method 103) , but the evaluation of cellulases is more complex and can vary from supplier to supplier. One common method is to measure the degradation of carboxymethylcellulose solutions. Another is to determine the weight or strength loss of standard cotton fabrics under laboratory conditions where there is a correlation problem, because the mechanical conditions of the technical application are different to the laboratory ones. For example, the hydrolysis degree, HD, is determined by HD = (m - m)/m where and m are the weight of the test material before and after bio-fmishing. 

Almost 3200 different enzymes have been listed and categorized by the International Union of Biochemistry and Molecular Biology in its last report in 1992. An encyclopaedic description of more than 7000 commercially available enzymes can be found in Ref [36]. Table 10.2 collects some industrial enzymes suppliers. Enzymes exhibiting the same catalytic function are known as homologous enzymes and they fall into two classes heteroenzymes and isoenzymes. The first group includes enzymes derived from different sources but which catalyse identical reactions, yet show different chemical and kinetic characteristics. A comprehensive enzyme information system, termed BRENDA, is available via the Internet (http //www.brenda.uni-koeln.de). 

Studies with one-enzyme systems on a laboratory scale with the aim of small scale production or verification of the desired concept do not require a detailed kinetic analysis. The properties of the enzyme and of the reaction system should be investigated to choose convenient assay and reaction conditions (e. g. temperature, pH value, substrate and cosubstrate concentrations). Typically some essential enzyme data are provided by the enzyme supplier or can be taken from handbooks [41]. 

Screening kits/sets containing samples of the normal commercially available enzymes are also provided by other enzyme suppliers, such as Boehringer Mannheim/Roche (Chirazyme sets for lipases/esterases, aldol reaction kits), Altus Biologies (ChiroScreen Kits TE and EH (based on CLECs, see section 5) for the chiral resolution of alcohols, amines, and esters), Biocatalysts (kits with alcohol dehydrogenases), Enzymatix (lipase biotransformation research kit), and others. 

Immobilization can be achieved by adsorption or covalent fixation of the biocatalyst to a solid support (e.g. surface-modified polymer or glass beads), by entrapment or by encapsulation in gel beads (e.g., agarose, polyacrylamide, alginate, etc.). Hundreds of immobilization methods have been described and reviewed in the literature [83-89], but only a limited set of methods has found real technical applications. The first large-scale applications of immobilized enzymes were established for the enantioseparation of D- and L-amino acids by Chib-ata, Tosa and co-workers at Tanabe Seiyaku Company. The Japanese achievements in the large-scale application of immobilized systems are very well documented in an excellent multi-author publication edited by Tanaka, Tosa and Kobayashi [90] (see also section 7). Some enzyme suppliers sell important industrial enzymes not only in the free form (solution or powder) but also immobilized on solid supports. 

Trioleoylglycerol (triolein) and olive oil are commonly used substrates, and stable emulsions may be readily obtained for use as substrate preparations. Enzyme activity can be monitored by a pH stat or analysis of released fatty acids (Brockerhoff and Jensen, 1974). The sensitivity of low-level activities may be increased with radioactive substrates. Tributyrin is commonly used because of its ease of dispersion in water, but it cannot be assumed that tributyrin hydrolysis is necessarily a measurement of true lipase activity. Triacetin is water-soluble, and although often used for lipase determinations this practice is not recommended. (A major commercial enzyme supplier markets wheat germ lipase but states on the containers that the preparation will not hydrolyze olive oil—it is, however, active on triacetin.)... 

The majority of commonly used enzyme preparations are available through chemical suppliers. Nevertheless, for economic reasons, it may be worth contacting an enzyme producer directly, in particular if bulk quantities are required. For a list of enzyme suppliers see the appendix (Chap. 5). After all, the exact structure of a Grignard-reagent is still unknown. 

A comparison of the activity of different enzyme preparations is only possible if the assay procedure is performed exactly in the same way. Since most enzyme suppliers use their own experimental setup, an estimation of the cost/ activity ratio of enzymes from various commercial sources is seldom possible by using published data and therefore activity data have to be determined independently. 

Novozymes A/S in Denmark, Genencor International Inc. in the United States, and DSM N.V. in the Netherlands are the three leading industrial enzymes suppliers. Examples of the industrial applications of enzymes are given in Table 1.4. 

Do consult your enzyme suppliers for a suitable process for enzyme scouring/bleaching and adopt the process at least for RFD quality fabric/yam. 

The amount of Zymolyase required may vary and should be predetermined for each combination of enzyme supplier and yeast strain. 

Enzyme suppliers are using various other methods to determine the activity of their products. Most of them are based on the evaluation of the color intensity at the end of the enzymatic reaction, which is proportional to the extent of substrate degradation. 

In the early days of biodetergent manufacture, some workers exposed to protease dust suffered from allergic reactions in the respiratory path [96-98] or from primary skin irritations [99-101]. Cases of occupational dermatitis can be found in the literature respiratory disease and minor skin irritation around facial mask, and cutaneous changes on hand and face [98,101,102]. These hazards practically led to the ban of enzymes in the United States in 1969-1970. Because of their large contribution to the cleaning process, considerable attention has been paid by enzyme suppliers and the detergent industry to solve the problem. 

Despite the diversity of sources and specificities, type II restriction enzymes have remarkably similar, simple reaction conditions (4,43-45). The restriction enzymes can thus be subgrouped according to refined optimal conditions, leading to reproducible and efficient uses of restriction enzymes in specific DNA cleavages (46). [Most enzyme suppliers offer their conditioned buffers in 10 x strength.]... 

A typical assay, which is commonly adopted by commercial enzyme suppliers, is based on the incorporation of labeled dNTPs by nick translation. The mixture (50 pi) contains 50 mM Tris-Cl (pH 9.0 at 25°C), 50 mM NaCl, 10 mM MgCl2, 0.2 mM each of dATP, dCTP, and dGTP, 50 pM [ H]dTTP, and 12.5 pg activated (DNase I-treated) calf thymus DNA. The mixture is incubated at 74°C. 

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