Biochemical reversal

Heslot, H. (1962) A quantitative study of biochemical reversions induced in the yeast Schizosaccharomyces pombe by radiations and radiomimetic substances. Abh. Dtsch. Akad. IViss. Berlin Kl. Med., 1, 19,3-228... 

Electroporation. When bacteria are exposed to an electric field a number of physical and biochemical changes occur. The bacterial membrane becomes polarized at low electric field. When the membrane potential reaches a critical value of 200—300 mV, areas of reversible local disorganization and transient breakdown occur resulting in a permeable membrane. This results in both molecular influx and efflux. The nature of the membrane disturbance is not clearly understood but bacteria, yeast, and fungi are capable of DNA uptake (see Yeasts). This method, called electroporation, has been used to transform a variety of bacterial and yeast strains that are recalcitrant to other methods (2). Apparatus for electroporation is commercially available, and constant improvements in the design are being made. 

Transient effects are those where there is repair of toxic physical injury or the reversal of induced biochemical aberrations. 

Biochemical studies showed that the a-aminoadipoyl analogue derived from (2,3)-P-methylenepenam was not a substrate for expandase activity but rather, it was a potent reversible inhibitor of the ring expansion of (7.-aminoadipoy1-penici11in into deacetoxycephalosporanic acid by the expandase enzyme... 

Surface-active agents and hquids immiscible in water can form tiny dispersed units called reverse micelles. These can extract biochemicals from water or permit complexing or reacting in ways not possible in simple aqueous systems. 

Cytochalasin B (from dehydrated mould matter) [14930-96-2] M 479.6. Purified by MeOH extraction, reverse phase Cl8 silica gel batch extraction, selective elution with 1 1 v/v hexane/tetrahydrofuran, crystn, subjected to TLC and recrystallised [Lipski et al. Aruil Biochem 161 332 1987]. 

Interleukin-2 (recombinant human) [94218-72-1] Mr-15,000, amorphous. Purified by reverse phase HPLC. [Weir and Sparks Biochem J 245 85 1 987 Robb et al. Proc Natl Acad Sci USA 81 6486 1984.]... 

In a very real sense, your body stores energy available from the metabolism of foods in the form of ATP. This molecule in turn supplies the energy required for all sorts of biochemical reactions taking place in the body. It does this by reverting to ADP, that is, by reversing reaction 17.6. The amount of ATP consumed is amazingly large a competitive sprinter may hydrolyze as much as 500 g (about 1 lb) of ATP per minute. 

Himnan DJ Tolerance and reverse tolerance to toluene inhalation effects on open-field behavior. Pharmacol Biochem Behav 21 625-631, 1984 Hinman DJ Biphasic dose-response relationship for effects of toluene inhalation on locomotor activity. Pharmacol Biochem Behav 26 65-69, 1987 Hormes JT, Filley CM, Rosenberg NL Neurologic sequelae of chronic solvent vapor abuse. Neurology 36 698—702, 1986... 

Arion D, Kaushik N, McCormick S, Borkow G, Parniak MA (1998) Phenotypic mechanism of HIV-1 resistance to 3 -azido-3 -deoxythymidine (AZT) increased polymerization processivity and enhanced sensitivity to pyrophosphate of the mutant viral reverse transcriptase, Biochem 37 15908-15917... 

Phosphate condensation reactions play an essential role in metabolism. Recall from Section 14.6 that the conversion of adenosine diphosphate (ADP) to adenosine triphosphate (ATP) requires an input of free energy ADP -I-H3 PO4 ATP +H2O AG° — +30.6kJ As also described in that section, ATP serves as a major biochemical energy source, releasing energy in the reverse, hydrolysis, reaction. The ease of interchanging O—H and O—P bonds probably accounts for the fact that nature chose a phosphate condensation/hydrolysis reaction for energy storage and transport. 

In extreme cases irritant chemicals can have a corrosive action. Corrosive substances can also attack living tissue (e.g. to cause skin ulceration and, in severe cases, chemical bums with degradation of biochemicals and charring), kill cells and possibly predispose to secondary bacterial invasion. Thus whilst acute irritation is a local and reversible response, corrosion is irreversible cell destmction at the site of the contact. The outcome is influenced by the nature of the compound, the concentration, duration of exposure, the pH (see Figure 5.1) and also, to some extent, by individual susceptibihty etc. Thus dilute mineral acids may be irritant whereas at higher concentrations they may cause corrosion. 

NAKANE H and ONO K (1990) Differential inhibitory effects of some catechin derivatives on the activities of human immunodeficiency virus reverse transcriptase and cellular deoyriboncleic and ribonucleic acid polymerases , Biochem, 29, 2841-5. 

During, A. et al., Assay of P-carotene 15,15-dioxygenase activity by reverse phase high-pressure liquid chromatography, Anal. Biochem., 241, 199, 1996. 

Chen, L. and Thacker, R. (1986). Vitamin C partially reversed some biochemical changes produced by vitamin E deficiency. Biotechnol. Appl. Biochem. 8, 40-45. 

Ziegler, D.M. (1985). Role of reversible oxidation-reduction of enzyme thiol-disulphides in metabolic regulation. Annu. Rev. Biochem. 54, 305-329. 

Martin, O. C. and Pagano, R. E., Normal- and reverse-phase separation of fluorescent (NBD) lipids, Anal. Biochem., 159, 101, 1986. 

Heinrikson, R. L. and Meredith, S. C., Amino acid analysis by reverse-phase high-performance liquid chromatography precolumn derivatization with phenylisothiocyanate, Anal. Biochem., 136, 65, 1984. 

Wimley, W. C. and White, S. H., Quantitation of electrostatic and hydrophobic membrane interactions by equilibrium dialysis and reverse-phase HPLC, Anal. Biochem., 213, 213, 1993. 

Titani, K., Sasagawa, T., Resing, K., and Walsh, K. A., A simple and rapid purification of commercial trypsin and chymostrypsin by reverse-phase high-performance liquid chromatography, Anal. Biochem., 123, 408, 1982. 

Berchtold, M. W., Heizmann, C. W., and Wilson, K. J., Ca2+-binding proteins a comparative study of their behavior during high-performance liquid chromatography using gradient elution in reverse-phase supports, Anal. Biochem., 129, 120, 1983. 

Cohen, K. A., Schellenberg, K., Benedek, K., Karger, B. L., Grego, B., and Hearn, M. T. W., Mobile-phase and temperature effects in the reversed phase chromatographic separation of proteins, Anal. Biochem., 140, 223, 1984. 

Thannhauser, T. W., McWherter, C. A., and Scheraga, H. A., Peptide mapping of bovine pancreatic ribonuclease A by reverse-phase high-performance liquid chromatography. II. A two-dimensional technique for determination of disulfide pairings using a continuous-flow disulfide detection system, Anal. Biochem., 149, 322, 1985. 

Most suitable would be the use of a perfectly NH4+ ion-selective glass electrode however, a disadvantage of this type of enzyme electrode is the time required for the establishment of equilibrium (several minutes) moreover, the normal Nernst response of 59 mV per decade (at 25° C) is practically never reached. Nevertheless, in biochemical investigations these electrodes offer special possibilities, especially because they can also be used in the reverse way as an enzyme-sensing electrode, i.e., by testing an enzyme with a substrate layer around the bulb of the glass electrode. 

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