Flavor-protein binding: disulfide interchange reactions between ovalbumin and volatile disulfides     

Adams RL  Mottram DS  Parker JK  Brown HM 《Journal of agricultural and food chemistry》2001,49(9):4333-4336

The irreversible binding of selected sulfur-containing flavor compounds to proteins was investigated in aqueous solutions containing ovalbumin and a mixture of disulfides (diethyl, dipropyl, dibutyl, diallyl, and 2-furfuryl methyl) using solid-phase micro-extraction (SPME). In systems which had not been heated, the recovery of disulfides from the headspace above the protein at the native pH (6.7) was similar to that from an aqueous blank. However, significant losses were observed when the pH of the solution was increased to 8.0. When the protein was denatured by heating, much greater losses were observed and some free thiols were produced. In similar heat-denatured systems at pH 2.0, no losses of disulfides were observed. Disulfides containing allyl or furfuryl groups were more reactive than saturated alkyl disulfides. Interchange reactions between protein sulfhydryl groups and the disulfides are believed to be responsible for the loss of the disulfides.  相似文献   

Input-Output Budgets of Inorganic Nitrogen for 24 Forest Watersheds in the Northeastern United States: A Review     

Campbell  John L.  Hornbeck  James W.  Mitchell  Myron J.  Adams  Mary Beth  Castro  Mark S.  Driscoll  Charles T.  Kahl  Jeffrey S.  Kochenderfer  James N.  Likens  Gene E.  Lynch  James A.  Murdoch  Peter S.  Nelson  Sarah J.  Shanley  James B. 《Water, air, and soil pollution》2004,151(1-4):373-396

Input-output budgets for dissolved inorganic nitrogen (DIN) are summarized for 24 small watersheds at 15 locations in the northeasternUnited States. The study watersheds are completely forested, free of recent physical disturbances, and span a geographical region bounded by West Virginia on the south and west, and Maine on the north and east. Total N budgets are not presented; however, fluxes of inorganic N in precipitation and streamwater dominate inputs and outputs of N at these watersheds. The range in inputs of DIN in wet-only precipitation from nearby National Atmospheric Deposition Program (NADP) sites was 2.7 to 8.1 kg N ha^-1 yr^-1 (mean = 6.4 kg N ha^-1 yr^-1; median = 7.0 kg N ha^-1 yr^-1). Outputs of DIN in streamwater ranged from 0.1 to 5.7 kg N ha^-1 yr^-1 (mean = 2.0 kg N ha^-1 yr^-1; median = 1.7 kg N ha^-1 yr^-1). Precipitation inputs of DIN exceeded outputs in streamwater at all watersheds, with net retention of DIN ranging from 1.2 to 7.3 kg N ha^-1 yr^-1 (mean = 4.4 kg N ha^-1 yr^-1; median = 4.6 kg N ha^-1 yr^-1). Outputs of DIN in streamwater were predominantly NO₃-N (mean = 89%; median = 94%). Wet deposition of DIN was not significantly related to DIN outputs in streamwater for these watersheds. Watershed characteristics such as hydrology, vegetation type, and land-use history affect DIN losses and may mask any relationship between inputs and outputs. Consequently, these factors need to be included in the development of indices and simulation models for predicting 'nitrogen saturation' and other ecological processes.  相似文献   

p53- and drug-induced apoptotic responses mediated by BH3-only proteins puma and noxa     

Villunger A  Michalak EM  Coultas L  Müllauer F  Böck G  Ausserlechner MJ  Adams JM  Strasser A 《Science (New York, N.Y.)》2003,302(5647):1036-1038

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Multicolor and electron microscopic imaging of connexin trafficking     

Gaietta G  Deerinck TJ  Adams SR  Bouwer J  Tour O  Laird DW  Sosinsky GE  Tsien RY  Ellisman MH 《Science (New York, N.Y.)》2002,296(5567):503-507

Recombinant proteins containing tetracysteine tags can be successively labeled in living cells with different colors of biarsenical fluorophores so that older and younger protein molecules can be sharply distinguished by both fluorescence and electron microscopy. Here we used this approach to show that newly synthesized connexin43 was transported predominantly in 100- to 150-nanometer vesicles to the plasma membrane and incorporated at the periphery of existing gap junctions, whereas older connexins were removed from the center of the plaques into pleiomorphic vesicles of widely varying sizes. Selective imaging by correlated optical and electron microscopy of protein molecules of known ages will clarify fundamental processes of protein trafficking in situ.  相似文献   

Subcellular calcium transients visualized by confocal microscopy in a voltage-clamped vertebrate neuron   总被引：25，自引：0，他引：25  

A Hernández-Cruz  F Sala  P R Adams 《Science (New York, N.Y.)》1990,247(4944):858-862

Confocal laser-scanned microscopy and long-wavelength calcium (Ca2+) indicators were combined to monitor both sustained and rapidly dissipating Ca2+ gradients in voltage-clamped sympathetic neurons isolated from the bullfrog. After a brief activation of voltage-dependent Ca2+ channels, Ca2+ spreads inwardly, and reaches the center of these spherical cells in about 300 milliseconds. Although the Ca2+ redistribution in the bulk of the cytosol could be accounted for with a radial diffusion model, local nonlinearities, suggesting either nonuniform Ca2+ entry or spatial buffering, could be seen. After electrical stimulation, Ca2+ signals in the nucleus were consistently larger and decayed more slowly than those in the cytosol. A similar behavior was observed when release of intracellular Ca2+ was induced by caffeine, suggesting that in both cases large responses originate from Ca2+ release sites near or within the nucleus. These results are consistent with an amplification mechanism involving Ca2(+)-induced Ca2+ release, which could be relevant to activity-dependent, Ca2(+)-regulated nuclear events.  相似文献   

Cholera: new aids in treatment and prevention   总被引：1，自引：0，他引：1  

M M Adams 《Science (New York, N.Y.)》1973,179(73):552-555

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Pentapeptide (proctolin) associated with an identified neuron   总被引：2，自引：0，他引：2  

M O'Shea  M E Adams 《Science (New York, N.Y.)》1981,213(4507):567-569

Individual neurons can be recognized and identified anatomically, physiologically, and biochemically in the insect central nervous system. Biochemical analyses of extracts prepared from one such identified neuron show it to be associated with a bioactive pentapeptide called proctolin. This peptide may be a neurotransmitter, and a preparation is established in which its physiological action can be studied at the cellular level.  相似文献   

Ultrafast bond softening in bismuth: mapping a solid's interatomic potential with X-rays     

Fritz DM  Reis DA  Adams B  Akre RA  Arthur J  Blome C  Bucksbaum PH  Cavalieri AL  Engemann S  Fahy S  Falcone RW  Fuoss PH  Gaffney KJ  George MJ  Hajdu J  Hertlein MP  Hillyard PB  Horn-von Hoegen M  Kammler M  Kaspar J  Kienberger R  Krejcik P  Lee SH  Lindenberg AM  McFarland B  Meyer D  Montagne T  Murray ED  Nelson AJ  Nicoul M  Pahl R  Rudati J  Schlarb H  Siddons DP  Sokolowski-Tinten K  Tschentscher T  von der Linde D  Hastings JB 《Science (New York, N.Y.)》2007,315(5812):633-636

Intense femtosecond laser excitation can produce transient states of matter that would otherwise be inaccessible to laboratory investigation. At high excitation densities, the interatomic forces that bind solids and determine many of their properties can be substantially altered. Here, we present the detailed mapping of the carrier density-dependent interatomic potential of bismuth approaching a solid-solid phase transition. Our experiments combine stroboscopic techniques that use a high-brightness linear electron accelerator-based x-ray source with pulse-by-pulse timing reconstruction for femtosecond resolution, allowing quantitative characterization of the interatomic potential energy surface of the highly excited solid.  相似文献   

Chronic arthritis in goats caused by a retrovirus   总被引：46，自引：0，他引：46  

T B Crawford  D S Adams  W P Cheevers  L C Cork 《Science (New York, N.Y.)》1980,207(4434):997-999

A virus was isolated from an adult goat with chronic arthritis and shown to belong to the retrovirus group by electron microscopy and biochemical methods. Inoculation of the virus into cesarean-derived specific-pathogen-free goats' kids produced arthritic lesions similar to those in the spontaneous disease. Vrus was reisolated from the experimentally induced lesions.  相似文献   

Clonal characteristics of experimentally induced "atherosclerotic" lesions in the hybrid hare   总被引：2，自引：0，他引：2  

T A Pearson  J Dillman  K J Williams  J A Wolff  R Adams  K Solez  R H Heptinstall  H Malmros  N Sternby 《Science (New York, N.Y.)》1979,206(4425):1423-1425

The female hybrid hare (Lepus timidus x Lepus europaeus) is heterozygous for electrophoretically separable, X-linked isoenzymes of glucose-6-phosphate dehydrogenase. The isoenzymes of this animal have been used as cellular markers in the study of the clonal origins of experimentally induced atherosclerotic lesions. Aortic lesions produced in the hybrid hare by feeding cholesterol and injuring the aortic wall with a catheter have been shown to have polyclonal characteristics and in this way are fundamentally different from atherosclerotic fibrous plaques in man.  相似文献