Enzymes evidence

There is ample evidence from both animal experiments and tissue cultures studies to show that brassica vegetables and their constituents selectively induce Phase II enzymes. Evidence for the induction of Phase II enzymes by... 

The above transketolase and transaldolase reactions were found inadequate to explain the metabolism of D-ribose 5-phosphate, because of the non-accumulation of tetrose phosphate, the 75 % yield of hexose phosphate, and the results of experiments with C14 (the distribution of which differed markedly from the values predicted for such a sequence). 24(b) Thus, with D-ribose-l-C14, using rat-liver enzymes, any hexose formed should have equal radioactivity at Cl and C3, whereas, actually, 74% appeared at Cl. Furthermore, D-ribose-2,3-Cl42 should have given material having equal labels at C2 and C4 in the resultant hexose, whereas, in fact, it had 50% of the activity at C4, C3 was nearly as active as C2, and Cl had little activity. Similar results were obtained with pea-leaf and -root preparations.24 The following reactions, for which there is enzymic evidence,170(b) were proposed, in addition to those involving D-aftro-heptulose, to account for these results.24(b) (o) 200... 

K10. Kirkman, H. N., and Bynum, E., Enzymic evidence of a galactosemic trait in parents of galactosemic children. Ann. Human Genet. 23, 117-126 (1959). 

Breslow, R., How do imidazole groups catalyze the cleavage of RNA in enzyme models and enzymes Evidence from negative catalysis. Acc. Chem. Res. 24 317, 1991. 

In their early efforts to apply the by-product design to ACE, Patchett and Maycock had synthesized only succinylproline, based on the findings of Byers and Wolfenden that benzylsuccinate was superior to ben-zylglutamate as an inhibitor of carboxypeptidase A. Similar active site topologies were assumed for these two enzymes. Evidently this was not the case, since Cushman et al. reported in 1977 (96) that glutarylpro-line (compound 6 Table II.) was more active than compound 5 (Table... 

Egelrud, T., Stratum corneum chymotryptic enzyme evidence of its location to the stratum corneum extracellular space, Eur. J. Dermatol., 2, 50, 1992. 

Franzke, C.W., Baici, A., Bartels, J., Christophers, E., and Wiedow, O., Antileukoprotease inhibits stratum corneum chymotryptic enzyme evidence for a regulative function in desquamation, J. Biol. 

Kossmann, J., Visser. R. F., Miiller-R6ber, B. T., Willmitzer, L., and Sonnewald. U. 1991. Cloning and expression analysis of a potato cDNA that encodes branching enzyme Evidence for coexpression of starch biosynthetic genes. Mol. Gen. Genet. 230, 39-44. 

Hazzard, J. T., McDonough, C. A., and Tollin, G., 1994, Intramolecular electron transfer in yeast flavocytochrome b2 upon one-electron photooxidation of the fully reduced enzyme evidence for redox state control of heme-flavin communication. Biochemistry 33 13445nl3454. 

The efficiency of the citric acid cycle may be enhanced by the arrangement of the constituent enzymes. Evidence is accumulating that the enzymes are physically associated with one another to facilitate substrate channeling between active sites. The word metabolon has been suggested as the name for such multienzyme complexes. 

Reaction (b) was intended to model a simpler reduction by NADH. In the laboratory it is very difficult to find any simple carbonyl compounds that are reduced by NADH in the absence of the enzyme. Evidently, the mild general acid catalysis at the carbonyl group is needed for the reaction to occur. This model works because (1) the iminium salt is more reactive than a simple aldehyde and (2) the product contains two benzene rings. 

Andersson T, Flockhart DA, Goldstein DB, et al. Drug-metabolizing enzymes evidence for clinical utility of pharmacogenomic tests. Clin Pharmacol Ther 2005 78(6) 559—81. 

Jamall IS, Naik M, Sprowls JJ, et al. 1989. A comparison of the effects of dietary cadmium on heart and kidney antioxidant enzymes Evidence for the greater vulnerability of the heart to cadmium toxicity. J Appl Toxicol 9(5) 339-345. 

Lykke-Andersen, J.. Garrett, R.A. and Kjems. J. (1996). Protein footprinting approach to mapping DNA binding sites of two archael homing enzymes evidence for a two-domain protein structure. Nucleic Acids Res. 24, 3982-3989. 

The isolation - of the 5-phosphate of N-(9-j3-D-ribofuranosyl-9 f-purin-6-yl)aspartic acid (26) from liver supports enzymic evidence ... 

The biochemical role of ascorbic acid in maintaining the pHPP oxidase reaction in vivo when extra tyrosine is fed is similar to its role in the usual in vitro assays. The mechanism of this effect is still obscure. It is shared by the other stereoisomers of ascorbic acid and by certain other compounds such as dichlorophenolindophenol. It consists of maintaining the reaction against an inhibition which develops without ascorbic acid. It has been suggested (HI, Z1) that an inhibitor is formed from the substrate, or alternatively, that the inhibition is a reaction inactivation of the enzyme. Evidence in favor of the latter is the reversal of the inhibition by incubation of the enzyme with dichlorophenolindophenol (Kll). 

In a perspective provided by structure of the Periodic Table, molybdenum and tungsten are distinct in being the only 4d- and 5d-transition metals that are required for the normal metabolism of biological systems. These metals play a vital role as the catalytic centres of a wide variety of enzymes. Mo was first identified as an essential trace element in the 1930s, because of its role in nitrogen fixation this metal is now known to be the catalytic centre of over 50 enzymes. Evidence for the involvement of W in biological systems has been obtained only relatively recently, especially for enzymes of hyperthermophilic archea that thrive near lOOX. ... 

Table 10.1 gives values of rate constants, activation energies, and frequency factors for three enzyme-catalyzed reactions. For comparison, the values for other catalysts are included. Note that molecule for molecule, the enzymes are much more effective catalysts than the nonbiological catalysts. In urease and catalase this higher effectiveness is related to a much smaller activation energy, which is true for a number of other enzyme systems. Enzymes evidently exert their action by allowing the process to occur by a much more favorable reaction path. 

Panda, D.K., D. Miao, M.L. Tremblay, J. Sirois, R. Farookhi, G.N. Hendy et al. (2001). Targeted ablation of the 25-hydroxyvitamin D la-hydrox-ylase enzyme Evidence for skeletal, reproductive, and immune dysfunction. Proc. Natl. Acad. Sci. USA 98, 7498-7503. 

Nicotine.—A wealth of experimental work has led to confusion rather than clarity about the biosynthesis of the pyrrolidine ring of nicotine (60). Tracer and enzymic evidence seems to favour a pathway involving at least one symmetrical intermediate (putrescine), illustrated in Scheme 5, although others are possible. 

Ingebritsen, T.S. Lee, H.-S. Parker, R.A. Gibson, D.M. Reversible modulation of the activities of both liver microsomal hydroxymethylglutaryl coenzyme A reductase and its inactivating enzyme. Evidence for regulation by phosphorylation-dephosphorylation. Biochem. Biophys. Res. Commun., 81, 1268-1277 (1978)... 

The enzyme contained three atoms of iron per molecule of the enzyme (molecular weight = approximately 140,000). All the iron in the native enzyme was shown to be in the divalent state, by ESR and colorimetric determinations. The enzyme was easily inactivated by an equimolar amount of H2O2 preincubated with the enzyme. Evidence indicates that inactivation is caused by simple oxidation of the ferrous ion to its ferric form (13). As Figure 1 shows, however, inactivation of the enzyme was completely counteracted by the presence of substrate, catechol. The reaction mixture contained 50 mM potassium phosphate buffer, pH 7.5, about 10 /xgrams of dialyzed enzyme, 5 /xM H2O2, and catechol (concentrations as indicated), in a final volume of 1.0 ml. All incubations were carried out at 24°C. for 10 minutes under anaerobic conditions. Activities were measured by the standard assay method (JO) with an aliquot of the mixture. 

Beacham, I.R., Haas, D. and Yagil, E. (1977) Mutants of Escherichia coii cryptic for certain periplas-mic enzymes evidence for an alteration of the outer membrane. Journai of Bacterioiogy 129, 1034-1044. 

Mil. Mason, M., and Gullekson, E., Interaction of estrogen sulfates with B -enzymes Evidence for physiological significance. Fed. Proc., Fed. Amer. Soc. Exp. Biol. 19, 170 (I960). 

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