PubMed · 6615682
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G G Graham, D Rigg. 1983. Nitroprusside infusions.. https://doi.org/10.1093/bja%2F55.9.919-a
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Activation volumes (delta V++) have been determined for several reactions of peroxynitrite using the stopped-flow technique. Spontaneous decomposition of ONOOH to NO3- in 0.15 M phosphate, pH 4.5, gave delta V++ = 6.0 +/- 0.7 and 14 +/- 1.0 cm3 mol-1 in the presence of 53 microM and 5 mM nitrite ion, respectively. One-electron oxidations of Mo(CN)8(4-) and Fe(CN)6(4-), which are first order in peroxynitrite and zero order in metal complex, gave delta V++ = 10 +/- 1 and 11 +/- 1 cm3 mol-1, respectively, at pH 7.2. The limiting yields of oxidized metal complex were found to decrease from 61 to 30% of the initially added peroxynitrite for Mo(CN)8(3-) and from 78 to 47% for Fe(CN)6(3-) when the pressure was increased from 0.1 to 140 MPa. The bimolecular reaction between CO2 and ONOO- was determined by monitoring the oxidation of Fe(CN)6(4-) by peroxynitrite in bicarbonate-containing 0.15 M phosphate, pH 7.2, for which delta V++ = -22 +/- 4 cm3 mol-1. The Fe(CN)6(3-) yield decreased by approximately 20% upon increasing the pressure from atmospheric to 80 MPa. Oxidation of Ni(cyclam)2+ by peroxynitrite, which is first order in each reactant, was characterized by delta V++ = -7.1 +/- 2 cm3 mol-1, and the thermal activation parameters delta H++ = 4.2 +/- 0.1 kcal mol-1 and delta S++ = -24 +/- 1 cal mol-1 K-1 in 0.15 M phosphate, pH 7.2. These results are discussed within the context of the radical cage hypothesis for peroxynitrite reactivity.
The effect of soaking, autoclaving and toasting methods on the proximate and mineral composition and anti-nutrients of lima (butter) bean (Phaseolus lunatus L.) was investigated. The raw seed showed high content of proteins, lipids and ash with good values of K, Ca, Mg, P, Na and Fe in comparison with other legumes. Potassium was the most abundant macro mineral while sodium was the least. Iron content was the highest among the micro minerals. Manganese was not detected in any of the samples. Raw lima bean contained cyanide, trypsin inhibitor, lectin, phytin and tannin. Phytate phosphorus was calculated to be 28.2% of total phosphorus. There was no significantly different (P > 0.05) in the crude protein content of raw and processed flour. There was significant difference (P < 0.05) in the values of the macro and micro mineral. Soaking, autoclaving and toasting completely eliminated trypsin inhibitor and lectin while it significantly (P < 0.05) reduced the levels of phytin, tannin and cyanide. Except for tannin autoclaving for 20 min was found to eliminate all the other anti-nutrients in lima bean.
Using the tetrazolium salt XTT (Na,3'-[(phe-nylamino)-carbonyl]-3,4-tetrazolium]-bis(4-methoxy-6-nitro)benzenesulfonic acid hydrate) as a sensitive and physiologically compatible probe for the determination of superoxide (O2*-) production in vivo, we have shown that maize (Zea mays L.) coleoptiles possess the capacity of generating O2*- in the apoplastic space. Our results are in agreement with the notion that this activity is localized at the plasma membrane and can be attributed to an O2*--synthesizing enzyme with catalytic and kinetic properties similar to that of the NADPH oxidase of mammalian phagocytes, with the important exception that it utilizes NADH instead of NADPH as electron donor. When applied to the apoplastic space, NADH strongly increased the O2*--producing activity of coleoptiles. The maize NADH-dependent O2*--synthase activity could clearly be differentiated from peroxidase-mediated O2*--synthesizing activity by its insensitivity to cyanide and azide, as well as by its much higher affinity to O2. Formation of O2*-, and concomitantly appearing H2O2, was preferentially localized in the outer epidermis of the coleoptile. The physiological significance of O2*- and H2O2 production in relation to the growth-controlling function of the epidermal cell wall is discussed.