Imidazole- And Base-Catalyzed Hydrolysis of Penicillin in Frozen Systems

Grant, Norman H.; Clark, Donald R.; Alburn, Harvey E.

doi:10.1021/ja01482a047

Cited by 70 publications

(42 citation statements)

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“…Indeed, species such as CH 2 O, and possibly others, have a small but non-zero solubility in ice (Burkhart et al, 2002;Perrier et al, 2003), and it is possible that this segregation takes place only once this solubility limit is exceeded, which happens in the laboratory but not in nature. The concentration-enhancing effect in partially frozen aqueous solutions also has been described in connection with the acceleration of some thermal reactions since the 1960s (Grant et al, 1961;Bruice and Butler, 1964;Butler and Bruice, 1964;Fennema, 1975;Takenaka et al, 1992;Takenaka et al, 1996). Recent work has illustrated that the freeze-concentration effect can also have significant impacts on the photochemistry of organics occurring in the QLL on the surface of ice (Bausch et al, 2006).…”

Section: Interaction Of Organics With Icementioning

confidence: 99%

An overview of snow photochemistry: evidence, mechanisms and impacts

et al. 2007

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Abstract. It has been shown that sunlit snow and ice plays an important role in processing atmospheric species. Photochemical production of a variety of chemicals has recently been reported to occur in snow/ice and the release of these photochemically generated species may significantly impact the chemistry of the overlying atmosphere. Nitrogen oxide and oxidant precursor fluxes have been measured in a number of snow covered environments, where in some cases the emissions significantly impact the overlying boundary layer. For example, photochemical ozone production (such as that occurring in polluted mid-latitudes) of 3-4 ppbv/day has been observed at South Pole, due to high OH and NO levels present in a relatively shallow boundary layer. Field and laboratory experiments have determined that the origin of the observed NO x flux is the photochemistry of nitrate within the snowpack, however some details of the mechanism have not yet been elucidated. A variety of low molecular weight organic compounds have been shown to be emitted from sunlit snowpacks, the source of which has been proposed to be either direct or indirect photo-oxidation of natural organic materials present in the snow. Although myriad studies have observed active processing of species within irradiated snowpacks, the fundamental chemistry occurring remains poorly understood. Here we consider the nature of snow at a fundamental, physical level; photochemical processes within snow and the caveats needed for comparison to atmospheric photochemistry; our current understanding of nitrogen, oxidant, halogen and organic photochemistry within snow; the current limitations faced by the field and implications for the future.

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Section: Interaction Of Organics With Icementioning

confidence: 99%

An overview of snow photochemistry: evidence, mechanisms and impacts

et al. 2007

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“…Some reactions have been known to be accelerated by freezing or in frozen systems compared to those in solution [1][2][3][4][5][6][7][8][9][10]. In the 1960s, acceleration of reactions by freezing or in frozen systems had been investigated mainly in food chemical, biochemical, and organic fields.…”

Section: Introductionmentioning

confidence: 99%

Rapid reaction of sulfide with hydrogen peroxide and formation of different final products by freezing compared to those in solution

Takenaka

Furuya

Sato

et al. 2003

Int J of Chemical Kinetics

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The reaction of sulfide with hydrogen peroxide in an aqueous solution at pH 9 produces thiosulfate, sulfite, and an unknown sulfur compound as intermediates, and, finally, all sulfides convert to sulfate (Chen and Gupta, Environ Lett 1973, 4, 187-200; Yokosuka et al., Nihon Kagaku Kaishi 1975, 11, 1901-1909 Hoffmann, Environ Sci Technol 1977, 11, 61-66; Ràbai et al., J Phys Chem 1992, 96, 5414-5419). This reaction was found to be accelerated by freezing. The decomposition rate of sulfide by H 2 O 2 in freezing at −15 • C was about 5 times faster than the maximum decomposition rate in solution at 25 • C. The decomposition of sulfide by freezing obeys zero-order kinetics, and the rate coefficient was 11.9 mol dm −3 min −1 at a freezing rate of 0.83 cm 3 min −1 . Zero-order kinetics is one of the characteristics of freezing rate-controlled reactions. Thiosulfate, sulfite, and an unknown sulfur compound were also observed as intermediates in the reaction by freezing. The decomposition of thiosulfate obeys first-order kinetics, and the rate coefficient was 0.0496 min −1 at −15 • C. The rate coefficient in freezing at −15 • C is about 47 times faster than that in solution at 25 • C. Sulfide, thiosulfate, and sulfite were consumed after 90 min. However, the unknown sulfur compound was not oxidized and was preserved in ice for a long time even in the presence of an excess of hydrogen peroxide. The concentration of an unknown sulfur compound in the frozen sample can be changed by changing the concentration of H 2 O 2 and the pH of the solution. Freezing could be used for rapid preparation and preservation of unstable substances in solution. C

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“…Damaging concentrations of electrolytes may also occur in the small volume of water remaining unfrozen (2). Furthermore, it is known that several hydrolytic and oxidative reactions proceed more rapidly in ice than in liquid water at 0 C (1, [10][11][12][13].…”

Section: Resultsmentioning

confidence: 99%

Freezing Damage to Isolated Tomato Fruit Mitochondria as Modified by Cryoprotective Agents and Storage Temperature

1970

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Isolated tomato (Lycopersicon esculentum var. Kc 146) fruit mitochondria could be stored successfully in the frozen state without a cryoprotective agent if the mitochondria were frozen quickly by immersion in liquid nitrogen and later thawed quickly at 30 C. Criteria of freezing damage were rate of respiration, adenosine diphosphate to oxygen ratio, and respiratory control ratio. Marked reduction in respiration and loss of respiratory control occurred when mitochondria were transferred from liquid nitrogen to -5, -10, or -18 C for 15 minutes prior to thawing at 30 C.Dimethylsulfoxide (5%Do) prevented freezing danmage when mitochondria were incubated at -5 C but did not prevent freezing damage at -10 or -18 C. There are a number of reports concerning freezing and animal mitochondria (8,(23)(24)(25) 33), but relatively little is known about how freezing affects isolated plant mitochondria. Heber and Santarius (18) reported that frozen and thawed spinach mitochondria partially retained phosphorylative and oxidative properties if sucrose was added, but protection was not as great as for photophosphorylation by chloroplasts. The spinach mitochondria were assayed with a-ketoglutarate as substrate, and all P/O ratios were less than 1. Hence, these workers may have observed the effect of freezing on the substrate level phosphorylation only.Our earlier work (5) showed that isolated tomato fruit mitochondria were severely damaged by freezing. Oxygen uptake decreased 89 /0 or more after 24 hr of storage at -18 C or in liquid nitrogen, and the damaged mitochondria lost respiratory control. The cryoprotective agent dimethylsulfoxide prevented freezing damage during storage in liquid nitrogen, and mitochondria were stored a month without decrease in ADP/O or loss of respiratory control.The present study also deals with freezing of isolated tomato mitochondria and is a continuation of the earlier work. Experiments were conducted to learn if DMSO3 was the only effective cryoprotective agent, whether rate of warming was related to a need for a cryoprotective agent, and the time course of freezing damage at several subzero temperatures.The cause of freezing damage is still not completely known (8,17,28), and the mode of action of cryoprotective agents is not clear (3,22,27,31). Isolated tomato mitochondria show promise for studying these phenomena. MATERIALS AND METHODSTomato fruit mitochondria were isolated and assayed with a Clark oxygen electrode as described earlier (5-7). Outer pericarp from mature green tomato fruits (Lycopersicon esculentunm, var.Kc 146) was ground at 0 C in a food mill with a medium (2 g of medium per g of tissue) containing 0.5 M mannitol, 0.05 Ni Na barbital (pH 7.8), 4 mm cysteine, 5 mm EDTA, and 1.5 mg/ml bovine serum albumin fraction V powder. The homogenate was strained through muslin, and mitochondria were collected as the fraction precipitating between 1,500g for 15 min and 15,000g for 15 min. Mitochondria were washed once in 0.5 M mannitol, 5 mm Na barbital, 1.5 mg,'ml bovine serum albumi...

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Imidazole- And Base-Catalyzed Hydrolysis of Penicillin in Frozen Systems

Cited by 70 publications

References 1 publication

An overview of snow photochemistry: evidence, mechanisms and impacts

An overview of snow photochemistry: evidence, mechanisms and impacts

Rapid reaction of sulfide with hydrogen peroxide and formation of different final products by freezing compared to those in solution

Freezing Damage to Isolated Tomato Fruit Mitochondria as Modified by Cryoprotective Agents and Storage Temperature

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