Specific activity, enzyme

The protein from D. desulfuricans has been characterized by Mbss-bauer and EPR spectroscopy 224). The enzyme has a molecular mass of approximately 150 kDa (three different subunits 88, 29, and 16 kDa) and contains three different types of redox-active centers four c-type hemes, nonheme iron arranged as two [4Fe-4S] centers, and a molybdopterin site (Mo-bound to two MGD). Selenium was also chemically detected. The enzyme specific activity is 78 units per mg of protein. 

Several scouting experiments were performed to find the best pH conditions. Figure 3 reports the ratio between the PG specific activity measured after the purification procedure (ASf) and the initial PG specific activity (ASi). At pH 3.5, the microspheres are able to remove from the broth the major part of the protein without PG activity, thus providing a four time increase of the enzyme specific activity. The purified PG from Kluyveromyces marxianus was immobilised following the above procedure. Batch reactions in the packed bed reactor were done to evaluate the biocatalyst stability. After an initial loss, due to enzyme release, the residual PG activity reaches a plateau value corresponding to about 40% of the initial activity. Probably, some broth component interfered during the immobilisation reaction weakening the protein-carrier interactions. 

It is possible to obtain a lysozyme-catalyzed lysis of substrates in mixed solvents. There is a partial and reversible inhibition showing that any organic solvent acts as a modifier of the enzyme specific activity. 

As pointed out in the preceding section, there are always unavoidable effects on enzyme specific activity of cosolvents used as antifreezes. The parameters m.app and/or are reversibly and significandy modified, casting doubts in the mind of biochemists about the real value of results obtained under such nonphysiological condidons. 

The enzyme activity is usually reported in units of substrate consumed or product produced over a given period of time, at near-saturating concentration of substrate and at a given pH or temperature. For a pure enzyme, specific activity can be reported, for example, as jmol or mmol/ min per mg enzyme-protein. 

The peptide substrate (400 pmol dissolved in 10 mM DTT immediately prior to use), [l-3H]famesyl diphosphate (200 pmol 15 Ci mmol-1) and farnesyltransferase (-200 units enzyme, specific activity 100-300 nmol h 1 mg1 protein) were mixed in buffer [30 pL 50 mM Tris-HCI (pH 7.7)/20 mM KQ/5 mM MgCl2/2 mM DTT]. The mixture was incubated for 20min at 37°C, then 0.1% octylglucoside was added and the reaction was allowed to proceed for 60 min. The product was purified by RP-HPLC on a C-18 column using a linear gradient of 10 to 100% MeCN in 0.1% aq TFA over 30min. Typical yield of the reaction is about 90%. 

Lei CH, Soares TA et al. (2008) Enzyme specific activity in functionalized nanoporous supports. Nanotechnology 19(12)... 

Enzyme Specific Activity Crude Km (mM) Vmax moles min-1ml-1... 

Sekine, H. (1973). Neutral proteinases II of Aspergilus sojae an enzyme specifically active on protamine and histone. Agric. Biol. Chem., 37, 1765-1767. 

Methods for estimating these corrections for cytochrome P450 (CYP) isoforms have been patented by the Camitro Corporation. The use of quantum mechanical (QM) methods in metabolism prediction thus varies in complexity. The simplest use is from the examination of empirical correlations of enzymic specific activity (pmol/min mg enzyme) with a single parameter such as the energy of the lowest unoccupied molecular orbital (ELUM0). 

Source Mix of Component Enzymes Specific Activity (FPU/g protein) Reference... 

It can be noted that the way in which the enzyme is prepared in the dry form for catalysis in organic solvent is responsible for striking differences (up to two orders of magnitude) in the enzyme-specific activity. Furthermore, it is worth mentioning that the transesterification activity of lipase from B. cepacia entrapped in sol gel (sol gel-AK-lipase BC) was 83% of the activity in water measured using tributyrin as a substrate [6]. Analogously, in the case of CALB lyophilized with methoxypoly(ethylene glycol) (CALB -i- PEG) the activity was 51% of the activity in water in the hydrolysis of vinyl acetate [7]. It is important to note that, for both... 

Fraction Total Volume (ml) Total Protein (mg) Total Enzyme Activity (nmole units/min) Enzyme Specific Activity (units/mg)... 

Developmental stage Enzyme specific activity [nmol/min/mg protein] ... 

Euling and Ambros 1996 Riddle 1988 Wadsworth and Riddle 1988), show considerable level of this mRNA (Fig. la and b). hi accord with thymidylate synthase specific activity, the enzyme mRNA level persists in dauer larvae for at least 6 weeks (Table 1 cf. Fig. 1). Additionally, comparison of the enzyme activity, enzyme protein and mRNA levels in adult worms, and LI, L3 and dauer larvae, shows only the enzyme protein and mRNA patterns (Table 1, Fig. 1, Results) to be correlated. Interestingly, the enzyme activity pattern parallels the two former patterns only with LI, L3 and dauer larvae, with the enzyme activity level in adult forms being low, relative to both mRNA and enzyme protein levels. The latter points to some regulation of enzyme protein expression and activity during the development. Of note is that T. spiralis thymidylate synthase mRNA levels showed no differences between adults, newborns and muscle larvae, with the enzyme specific activities in adults and muscle larvae also being comparable (Table 1, Fig. 1). 

Enzyme Specific activity U mg Relative activity % Amount of bound protein mg g dry carrier... 

Pale, btownish-green Crystals or shiny, transparent, striated plates. Practically insol in water. Slightly sol in buffered alkali solns. So] ns at pH 7.5-10.5 are relatively si able. Shows unusually high absorption in the region of 35777350 nm (for highly purified uricase AjS = 11-3, AJJj — 2.0, both in 1% Na,CO, Nm/Aija = 5.6). Isoelec, pt, pH 6.3. Copper content of the enzyme (specific activity [20-125) equals 0,56 mg/g of enzyme protein. There appears to be a satisfactory correlation between copper content and activi-iy of the purified enzyme. The enzyme is sensitive to cyanide ion the ptesence of I0-4M KCN inhibits its activity. 

E enzyme specific activity for a reaction in a time=/(U/g) Eq enzyme specific activity for r=0 (U/g) k observed deactivation rate constant ... 

Justification. Investigation of a number of gelatinous hydrous metal oxides (frequently called hydroxides, although their full structures are uncertain) has established ( ) that hydrous titanium (IV), zirconium (IV), iron (III), vanadium (III) and tin (II) oxides at least are capable of forming with enzymes insoluble complexes which are enzymically active. From the practical viewpoint hydrous titanium (IV) and zirconium (IV) oxides proved the most satisfactory. Comparatively high retentions of enzyme specific activity may be achieved (3, 4, 5). Such hydrous metal oxide materials have also proved to be suitable for the immobilisation of amino acids and peptides ( ), antibiotics with retention of antimicrobial activity ( ), polysaccharides J ), etc. 

More generally, it may be concluded that hydrous transition metal oxides are effective matrices for enzyme, etc, immobilisation. Their advantages include low cost, convenience of preparation (which may be conducted in any location without specialised facilities), the absence of any need for prepreparation, ability to couple enzyme at neutral pH, high retention of enzyme specific activity of the enzyme on immobilisation, and the ability of modification to exert microenvironmental effects on and thereby alter the characteristics of the immobilised enzyme. 

The economics of enzyme production are dominated in most cases by recovery costs. For this reason, the objective functions for optimization are to maximize the specific activity (units of enzyme activity per weight of cell mass) and volumetric productivity (units per liter-h). Maximization of specific activity ensures both efficient conversion of raw materials to the desired product as well as facilitating enzyme recovery maximization of total volumetric productivity helps to minimize recovery costs and maximize economic return on capital investment. To achieve these objectives in process development, one utilizes both genetic manipulations and environmental management to achieve a high enzyme specific activity and a high cell density. 

Enzyme Specific activity (u/g wet cell) Volumetric activity (u/L of broth) Productivity [u/(L-wk)]... 

Table 1. Specific activities (pmol [mg protein] h ) of enzymes involved in scavenging photoreduced species of dioxygen in Zea mays and Zea diploperennis leaves, assayed at 19 and The plants had not been chill stressed. Mean values SE of triplicate samples are given. Figures in parenthesis indicate the percentage reduction in enzyme specific activity at 5 C relative to 19 C.

The amount of dextranase attached to porous titanium(iv) oxide by chelation increased in the presence of ammonia, although more enzyme specific activity was retained in the absence of ammonia. Properties of the immobilized enzyme include a pH-dependence and reversibility of the coupling between the enzyme and the matrix. 

Pure pGal has a specific activity of —500 U/mg protein. A commercially available enzyme (specific activity >300 U/mg) is supplied as white powder obtained by lyophilization in 5 mM sodium phosphate, pH 7.2. 

Enzyme Specific activity hemolyate (nmoles/ml packed cells/min in 0,5 (mM) of partially purified enzyme ... 

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