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Patterns of Enzyme Activities

30 irnol L 1h 1 (Crump et al., 1998). The same pattern was observed during a phytoplankton bloom induced in a mesocosm, where maximum leu-MCA hydrolysis rates reached ca. 1065 nmol L 1h 1, MUF-p-glucosidase reached ca. 50 nmol L 1 h-1, and MUF-a-glucosidase activity reached 21 nmol L 1 h 1 (Riemann et al., 2000). [Pg.325]

The precise relationship between potential hydrolysis rates measured with externally added substrates and the rates at which complex microbial communities in marine systems hydrolyze and ultimately remineralize a spectrum of organic macromolecules actually available as substrates is unknown. Extracellular enzymatic hydrolysis is frequently regarded as the rate-limiting step in remineralization of organic carbon (e.g., King, 1986  [Pg.327]

FIGURE 1 Potential hydrolysis rates of six structurally distinct polysaccharides in seawater (A) and surface sediments (B) from Skagerrak and Svalbard. Pull = pullulan, lam = laminarin, xyl = xylan, fu = fucoidan, ara = arabinogalactan, chon = chondroitin sulfate. Note the differences in scale on the y axes for sediments and for seawater. [Skagerrak data from Arnosti (2000).] [Pg.328]

FIGURE 2 Degradation of pullulan (MW 200,000) in replicate anaerobic enrichment cultures of marine bacteria from anoxic sediments. Open circles show total pullulan concentrations remaining in the medium at each time point. The molecular weight distribution of the pullulan is shown by the stacked bars white 10,000 Da, stripes 5000 Da, black 1200 Da. Note that the lower molecular weight fraction progressively accumulated between 50 and 64 h. [Data from Arnosti et al. (1994).] [Pg.329]

Field studies point in a similar direction field comparisons of peptide hydrolysis rates and amino acid turnover in coastal sediments showed that amino acid production could exceed uptake by a factor of approximately 8 (Pantoja and Lee, 1999). A comparison of potential enzyme activities and sedimentary amino acid and carbohydrate inventories in sediments from the Ross Sea also showed that potential hydrolysis rates on time scales of hours should in theory rapidly deplete sedimentary amino acid and carbohydrate inventories (Fabiano and Danovaro, 1998). In deep-sea sediments, Poremba (1995) also found that potential enzyme activities in theory could exceed total sedimentary carbon input by a factor of 200. Finally, Smith et al. s (1992) investigation of potential hydrolysis rates and amino acid uptake in marine snow demonstrated that the particle-associated bacteria were potentially producing amino acids far in excess of their own carbon demand. [Pg.330]


The Morquio syndrome (type IV mucopolysaccharidosis) is associated with the excretion of large amounts of keratan sulfate in the urine.389 The patients appear to have a normal pattern of enzymic activities in the liver lysosomes.399 Types V (Scheie syndrome) and... [Pg.476]

Xanthine oxidase (EC 1.2.3.2) catalyzes the irreversible oxidation of hypoxanthine and xanthine to uric acid. Recently, we have shown that rat liver xanthine oxidase enzyme activity is, in part, dependent on both age-and sex-specific differences. Immaturity in both sexes, adult females and pubertal male castrates demonstrate a basal or feminine pattern of enzyme activity. Androgen is required in the pubescent period for the full expression of hepatic xanthine oxidase activity in the adult male. The effect of androgen exposure on hepatic enzyme activity, however, remains speculative. [Pg.511]

Based on the two analyses just described, a Ki value of 1.8 mM was used and the pattern of enzyme activity predicted using the model [Eqs. (14.10) through (14.13)] is shown as the lower curve in Fig. 14.11. It is apparent that although there is some systematic deviation of the actual data from the curve modeling substrate inhibition, the approximation to the data observed is nonetheless reasonable. [Pg.188]

Complement is not a single protein but comprises a group of functionally linked proteins that interact with each other to provide mar of the effector functions of humoral immunity and inflammation. Most of the components of the system are present in the serum as proenzymes, i.e. enzyme precursors. Activation of a complement molecule occurs as a result of proteolytic cleavage of the molecule, which in itself confers proteolytic activity on the molecule. Thus, many components of the system serve as the substrate of a prior component and, in turn, activate a subsequent component. This pattern of sequential activation results in the system being called the complement cascade. ... [Pg.291]

No information is available concerning the effects of 2,3-benzofuran in humans. Acute oral exposure to 2,3-benzofuran has been shown to alter levels of enzyme activity in the livers of female mice (Heine et al. 1986), but much more work would need to be done to determine whether there is a pattern of enzyme alteration specific to 2,3-benzofuran exposure. Other effects found in animals following oral exposure to 2,3-benzofuran are kidney and liver damage and kidney, lung, liver, and stomach cancer (see Section 2.2.2). Such generalized responses do not suggest the basis for any specific biomarker of clinical or preclinical effects caused by 2,3-benzofuran. [Pg.39]

These problems were overcome by immobilizing the enzyme. Since the usual methods for immobilization of laccase did not work, we adopted a new method, details of which will be described elsewhere (29). Reasonable measurements were possible with this technique. Typical patterns of laccase activity could be monitored via the changes of absorbance of 2,6 DMP and syringaldazine. When the reaction took place in organic solvents, the absorption spectra of the products were similar to those obtained for the same reaction in buffer. Furthermore, the catalytic action of the T. versicolor laccase followed Michaelis-Menten-kinetics in most of the organic solvents which were tested (see Table II for specific examples). [Pg.368]

In case of CDG-I IEF pattern, further investigations are initiated by the determination of PMM activity. PMM2 is the defective enzyme in the most widespread form of CDG known so far CDG-Ia (about 80% of all known CDG-cases). It is caused by mutations in the gene, which result in a severe decrease in PMM2 activity, catalysing the conversion of mannose-6-phosphate to mannose-1-phosphate in the cytosol (Fig. 4.5.1). Determination of enzyme activity may be carried out by incubation of protein extracts from patient-derived fibroblasts or leukocytes with [2-3H]mannose-... [Pg.392]

This subject has been of continuing interest for several reasons. First, the present concepts of the chemical constitution of such important biopolymers as cellulose, amylose, and chitin can be confirmed by their adequate chemical synthesis. Second, synthetic polysaccharides of defined structure can be used to study the action pattern of enzymes, the induction and reaction of antibodies, and the effect of structure on biological activity in the interaction of proteins, nucleic acids, and lipides with polyhydroxylic macromolecules. Third, it is anticipated that synthetic polysaccharides of known structure and molecular size will provide ideal systems for the correlation of chemical and physical properties with chemical constitution and macromolecular conformation. Finally, synthetic polysaccharides and their derivatives should furnish a large variety of potentially useful materials whose properties can be widely varied these substances may find new applications in biology, medicine, and industry. [Pg.432]

The discussion to this point has focused on the isolation of intact mitochondria. By various chemical and physical treatments, mitochondria may be separated into their four components. This allows biochemists to study the biological functions of each component. For example, by measuring enzyme activities in each fraction, one can assign the presence of a particular enzyme to a specific region of the mitochondria. Studies of mitochondrial subfractions have resulted in a distribution analysis of enzyme activities in the four locations (Table E10.1). This type of study is often referred to as an enzyme profile or enzyme activity pattern and the enzyme may be considered a marker enzyme. For example, cytochrome oxidase, which is involved in electron transport, is a marker enzyme for the inner membrane. [Pg.360]

Another pattern of reductive activation has been observed in the Ni hydrogenase of Methanobacterium formicicum (79). In this enzyme, reductive activation is irreversible, requires a strong reductant, and is inhibited by the chelating agent 2,2 -bipyridyl. The conversion of a [3Fe-xS] cluster to a [4Fe-4S] has been suggested. [Pg.320]

Protein pattern by Electrophoresis Special cases of enzyme activities (by specific analysis or mRNA blot) Some stress markers (by electrophoresis or mRNA blot) NADH by fluorescence... [Pg.188]

Because modulation of enzyme activities depends on metabolite concentrations, which in turn are determined by the entire metabolic network, the overall response time for these controls can be on the order of seconds. This is the same as the time scale for changes in environmental conditions (e.g., pH, dissolved oxygen concentration) encountered by cells as they circulate through the nonuniform contents of a large-scale bioreactor. Therefore, beyond the complexities of enzyme activity control in the steady state, dynamic properties of this control system are important. The circulation pattern in a bioreactor has major effects on product formation [28]. Lack of understanding of transient responses of cell metabolism is one central obstacle to systematic scale-up of laboratory results (obtained in idealized,... [Pg.448]

A discussion of the interpretation of enzyme activity banding patterns and the analysis of electrophoretic data is beyond the scope of this chapter. Details on the interpretation of zymograms can be found in several of the references cited herein.10 11 22 Richardson et a/.10 provide a thorough discussion of data analysis and present several detailed examples of analyses taken from the literature. Among the major computer software packages currently available for data analysis are BIOSYS-1 23 PAUP,24 PHYLIP,25... [Pg.91]

There appears to be no single pattern describing the hydration dependence of enzyme activity. Lysozyme activity is correlated with the unfreezing of surface motion at 0.25 A and also with the onset of surface percolation. There are changes in activity above 0.38 A, such as the changes found for rotational motion of TEMPONE. The hydration threshold for chymotrypsin activity, at 0.12 A, is substantially lower than that for lysozyme. A correlation with percolation is an attractive, but untested, possibility. [Pg.135]

Figure 3. Elution pattern of enzymes reducing ethyl 3-oxohexanoate on DEAE-Sepharose CL-6B chromatography with increasing NaCl concentration. ( O ) enzyme activity assay 1.5 ml 200 mM Tris-HCl buffer (pH 7.2), 0.2 ml 1 mM NADPH solution, 0.1 ml 50 mM ethyl 3-oxohexanoate (emulsified in an aqueuos solution of 5 % propylen-glycol) and 0.05 ml enzyme solution measuring the absorbance at 340 nm at 25 °C. ( ) enantiomeric composition (GC separation of MTPA-derivatives) of the formed ethyl 3-hydroxyhexanaote assay active fractions (tubes 16 to 23), ethyl 3-oxohexanoate (2 mg) and NADPH (1.5 mg) in a total volume of 3 ml 0.1 Tris-HCl buffer,... Figure 3. Elution pattern of enzymes reducing ethyl 3-oxohexanoate on DEAE-Sepharose CL-6B chromatography with increasing NaCl concentration. ( O ) enzyme activity assay 1.5 ml 200 mM Tris-HCl buffer (pH 7.2), 0.2 ml 1 mM NADPH solution, 0.1 ml 50 mM ethyl 3-oxohexanoate (emulsified in an aqueuos solution of 5 % propylen-glycol) and 0.05 ml enzyme solution measuring the absorbance at 340 nm at 25 °C. ( ) enantiomeric composition (GC separation of MTPA-derivatives) of the formed ethyl 3-hydroxyhexanaote assay active fractions (tubes 16 to 23), ethyl 3-oxohexanoate (2 mg) and NADPH (1.5 mg) in a total volume of 3 ml 0.1 Tris-HCl buffer,...

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