Side Path Research Articles

For the “Briefly Gorgeous” Moment: Imagism and Queer Aesthetics in Ocean Vuong’s On Earth We’re Briefly Gorgeous

ABSTRACT Ocean Vuong’s epistolary novel On Earth We’re Briefly Gorgeous is distinguished by its highly sensory, descriptive, and fragmented linguistic style, coupled with an anachronic, multi-line narrative strategy. These stylistic elements exemplify salient modernist aesthetics, particularly resonating with the tenets of the Imagist movement. Through the presentation of fleeting images and juxtaposed scenes across temporal and spatial boundaries, Vuong’s fiction delineates the narrator’s transient, synesthetic recollections which merge into a dynamic flow of conscious duration, constituting a notable queer racial formalist work. Moreover, Vuong’s richly sensory and affective portrayal facilitates an embodied engagement with external spaces, unraveling the complex layers of the protagonist’s Asian American queer identity. By integrating a corporeal perspective into the aesthetic process of receiving and composing, Vuong reconfigures the traditionally passive bottom role toward a more dynamic and inclusive queer performance, thus challenging the entrenched heteronormative constructions that comply with Western imperialist and masculinist discourses. Beyond empowering the “abject” bottom, Vuong’s novel also posits a shared vulnerability inherent in queer bodies, envisioning a side path for the minoritarian groups.

Isotope-labeled ergothioneine clarifies the mechanism of reaction with singlet oxygen.

Recently we have uncovered a non-enzymatic multi-step cycle for the regeneration of ergothioneine (ET), after reaction with noxious singlet oxygen (1O2), by glutathione (GSH). When living cells were loaded with ET labeled with deuterium and N-15 atoms (D5-ET) and exposed to light in the presence of a photosensitizer, no loss of deuterium at position 5 of the imidazole ring was observed, in contradiction to our previous mechanistic proposal. Therefore, it was necessary to reexamine the in vitro products of ET and 1O2 by liquid chromatography coupled to high resolution mass spectrometry. Pure 1O2 was generated by thermolysis at 37°C of the endoperoxide DHPNO2. The use of D5-ET enabled us to revise and extend the reaction scheme. On the main pathway, 1O2 attacks the imidazole ring, and the hydroperoxide intermediates are reduced rapidly by ET or GSH via different mechanisms. The intramolecular water elimination from the 5-hydroperoxide described previously is slower and not a part of the cycle. On another side path, 1O2 attacks the sulfur of ET to form a sulfine (S-oxide). The reduction of the sulfine also allows for the complete regeneration of ET. Experiments with methanol instead of water as solvent revealed that, in the absence of GSH, ET was attacked 6 times more frequently at the ring than at the sulfur. In the presence of 1mM GSH or higher, both side paths were abandoned. ET efficiently captures 1O2 with its ring and can then be regenerated to a large extent by GSH, without enzyme involvement.

Quantification of cytosol and membrane proteins in rumen epithelium of sheep with low or high CH4 emission phenotype.

BackgroundRuminant livestock are a major contributor to Australian agricultural sector carbon emissions. Variation in methane (CH4) produced from enteric microbial fermentation of feed in the reticulo-rumen of sheep differs with different digestive functions.MethodWe isolated rumen epithelium enzymatically to extract membrane and cytosol proteins from sheep with high (H) and low (L) CH4 emission. Protein abundance was quantified using SWATH-mass spectrometry.ResultsThe research found differences related to the metabolism of glucose, lactate and processes of cell defence against microbes in sheep from each phenotype. Enzymes in the methylglyoxal pathway, a side path of glycolysis, resulting in D-lactate production, differed in abundance. In the H CH4 rumen epithelium the enzyme hydroxyacylglutathione hydrolase (HAGH) was 2.56 fold higher in abundance, whereas in the L CH4 epithelium lactate dehydrogenase D (LDHD) was 1.93 fold higher. Malic enzyme 1 which converts D-lactate to pyruvate via the tricarboxylic cycle was 1.57 fold higher in the L CH4 phenotype. Other proteins that are known to regulate cell defence against microbes had differential abundance in the epithelium of each phenotype.ConclusionDifferences in the abundance of enzymes involved in the metabolism of glucose were associated with H and L CH4 phenotype sheep. Potentially this represents an opportunity to use protein markers in the rumen epithelium to select low CH4 emitting sheep.

La filosofia di Biancaneve. Spunti per i tempi che cambiano

Nicola Vitale walks a side path to the smooth march of technocratic rationalism. A rationalism dried up in the imagination, in the capacity for vision, in the sense of community belonging that makes us human beings, as Aristotle taught. Snow White, from a Disney fairy tale, returns to its symbolic powerful significance of alchemical narration where everything, even the most divisive evil, finds meaning and place.

3D Dense Volumetric Network for Accurate Automated Pancreas Segmentation.

Pancreatic cancer poses a great threat to our health with an overall five-year survival rate of 8%. Automatic and accurate segmentation of pancreas plays an important and prerequisite role in computer-assisted diagnosis and treatment. Due to the ambiguous pancreas borders and intertwined surrounding tissues, it is a challenging task. In this paper, we propose a novel 3D Dense Volumetric Network (3D2VNet) to improve the segmentation accuracy of pancreas organ. Firstly, 3D fully convolutional architecture is applied to effectively incorporate the 3D pancreas and geometric cues for volume-to-volume segmentation. Then, dense connectivity is introduced to preserve the maximum information flow between layers and reduce the overfitting on limited training data. In addition, a auxiliary side path is constructed to help the gradient propagation to stabilize the training process. Adequate experiments are conducted on a challenging pancreas dataset in Medical Segmentation Decathlon challenge. The results demonstrate our method can outperform other comparison methods on the task of automated pancreas segmentation using limited data.Clinical relevance-This paper proposes an accurate automated pancreas segmentation method, which can provide assistance to clinicians in the diagnosis and treatment of pancreatic cancer.

Context-aware co-supervision for accurate object detection

State-of-the-art object detection approaches are often composed of two stages, namely, proposing a number of regions on an image and classifying each of them into one class. Both stages share a network backbone which builds visual features in a bottom-up manner. In this paper, we advocate the importance of equipping two-stage detectors with top-down signals, in order to which provides high-level contextual cues to complement low-level features. In practice, this is implemented by adding a side path in the detection head to predict all object classes in the image, which is co-supervised by image-level semantics and requires little extra overheads. Our approach is easily applied to two popular object detection algorithms, and achieves consistent performance gain in the MS-COCO dataset.

Hot-cracking susceptibility and shear fracture behavior of dissimilar Ti6Al4V/AA6060 alloys in pulsed Nd:YAG laser welding

Laser welding of dissimilar titanium/aluminum alloys has been employed at an increasing rate, particularly in the aerospace industry, owing to its advantages in terms of current design flexibility and fuel/cost savings. The major problem with dissimilar Ti/Al welds arises from the difference in the thermal expansion and contraction of the two metals, which leads to hot-cracking susceptibility and the mitigation of the mechanical property after welding. In the present study, pulsed Nd:YAG laser welding of Ti6Al4V and AA6060 has been addressed. Hot-cracking susceptibility in the heat affected zone and the shear fracture behavior of the lap joints were investigated through microstructural characterization and mechanical tests. The results indicate that the hot cracking tendency can be reduced by increasing the pulse peak power (7.5–8.5 kW) and the laser point diameter (0.8–1.0 mm) with specific pulse duration and overlap. An alternative control strategy for less hot cracks in the Ti/Al lap joint can be to increase the weld width and decrease the cooling rate during solidification. The shear fracture of the Ti/Al lap joint is likely to occur along the lower side path of the weld interface with decreasing weld surface collapsed amount and increasing aluminum base metal melt depth.

Bicycle Level of Service Model for the Cycloruta, Bogota, Colombia

Abstract Segment videos were produced at different peaks to reflect different sampling criteria like land use characteristics, trails, Ciclocarrils and Ciclovia. Each segment was filmed for 20–40 seconds during bicycle rides at a speed of about 5km/h with a camera strapped, at an angle of 45 degrees, on the head. Curb lane variables such as bicycle pathway widths, curb lane motorised volume (veh/h) and vehicle speed (km/h), bicycle volume on segment, and median width were recorded in addition to secondary data. About 1,360 ratings were acquired from study participants and used in the estimation process. Ordered probability models were used to estimate random parameters of cyclists LOS perception to account for unobserved heterogeneity for all respondents. The deviance (1.085) and Pearson Chi-Square (2.309) with 1,635 degree of freedom at 0.05 level of significance shows that our model provides a better fit of the data. The study observed that BLOS was strongly influenced by side path separation, vehicle speed, motorised traffic volume and conflicts with pedestrians. However, many other factors were found to have high probabilities to influence level of service with unit change. They include bicycle lane width, wide outside lane, pavement conditions, trees and benches, daylight, gender and experience of cyclist. The impact of the variety of observed factors affecting bicyclists reveal the nature and character of urban transportation in Bogota which suggests a range of important trade-offs in further planning and management of the Cicloruta bicycle paths.

Molecular Insight into the Acryloyl-CoA Hydration by AcuH for Acrylate Detoxification in Dimethylsulfoniopropionate-Catabolizing Bacteria.

Microbial cleavage of dimethylsulfoniopropionate (DMSP) producing dimethyl sulfide (DMS) and acrylate is an important step in global sulfur cycling. Acrylate is toxic for cells, and thus should be metabolized effectively for detoxification. There are two proposed pathways for acrylate metabolism in DMSP-catabolizing bacteria, the AcuN-AcuK pathway and the PrpE-AcuI pathway. AcuH is an acryloyl-CoA hydratase in DMSP-catabolizing bacteria and can catalyze the hydration of toxic acryloyl-CoA to produce 3-hydroxypropionyl-CoA (3-HP-CoA) in both the AcuN-AcuK pathway and the side path of the PrpE-AcuI pathway. However, the structure and catalytic mechanism of AcuH remain unknown. Here, we cloned a putative acuH gene from Roseovarius nubinhibens ISM, a typical DMSP-catabolizing bacterium, and expressed it (RdAcuH) in Escherichia coli. The activity of RdAcuH toward acryloyl-CoA was detected by liquid chromatography-mass spectrometry (LC-MS), which suggests that RdAcuH is a functional acryloyl-CoA hydratase. Then we solved the crystal structure of RdAcuH. Each asymmetric unit in the crystal of RdAcuH contains a dimer of trimers and each RdAcuH monomer contains an N-terminal domain (NTD) and a C-terminal domain (CTD). There are three active centers in each trimer and each active center is located between the NTD of a subunit and the CTD of the neighboring subunit. Site-directed mutagenesis analysis indicates that two highly conserved glutamates, Glu112 and Glu132, in the active center are essential for catalysis. Based on our results and previous research, we analyzed the catalytic mechanism of AcuH to hydrate acryloyl-CoA, in which Glu132 acts as the catalytic base. This study sheds light on the mechanism of acrylate detoxification in DMSP-catabolizing bacteria.

Second-Generation Memory and Contemporary Children’s Literature: Ghost Images by Anastasia Ulanowicz (review)

Reviewed by: Second-Generation Memory and Contemporary Children’s Literature: Ghost Images by Anastasia Ulanowicz Hamida Bosmajian (bio) Second-Generation Memory and Contemporary Children’s Literature: Ghost Images, by Anastasia Ulanowicz. New York: Routledge, 2013. The energy that drives Anastasia Ulanowicz’s Second-Generation Memory and Contemporary Children’s Literature: Ghost Images are the ghost images that haunt her, palimpsests of memories overheard and gathered as she listened to her elders as a child (xi). Although she interprets only five narratives of children’s literature, “case studies” she calls them, [End Page 285] her range and scope sweep wide. There are times the reader may fear she is wandering too far down a critical side path, but then she always hooks up seamlessly with her main argument and the reader concedes: “Aha, you know where you are going.” Ulanowicz accepts Samantha Power’s haunting definition of the twentieth century as “the age of genocide”(3). Soon there will be only second-generation memory narratives, even when a narrator imagines being an eyewitness. Ulanowicz’s focus is timely and the questions she raises in her well-researched analogical and associative discussions contribute in major ways to future explorations, for there will be—there are already—third-generation receivers of memory. “If ‘children’s literature of atrocity’ is a relatively new phenomenon,” she asks, “then how might its development coincide with equally newly emerging theories of memory?” (4). The scholars she consults are, however, not those who explore the cognitive and neurological or even the psychological development of the child faculty of memory; rather, they are in the humanist tradition of philosophy and the social sciences. Like Jonas in Lowry’s The Giver, Ulanowicz listens respectfully to her “elders” who inspire her in her “case studies” as she endeavors to effect a new direction in how we talk when we talk about narratives of atrocity at this juncture of our cultural history. Forgetting is the “shadowy twin”(31) of remembering. We want and we need to forget—and we will forget. Forgetting may be our undoing or our survival. Remembering demands a tremendous and often painful effort, spurred by ethical impulses and by critical consciousness, especially where disaster and trauma are at stake. All second-generation memory is collective, but second-generation memory receivers are aware that, in one way or another, they are shaped by the first generation. In her helpful introduction Ulanowicz points out that receivers of that context can never replicate the first generation’s traumatic experiences and reactions, but they can reimagine and reshape them, even incorporate them “as if [their] life depended on it—because, in a sense it does” (15). There is an inherent ethical, if not radically revolutionary inclination in second-generation memory, though Ulanowicz, while officially emphasizing it, doubts its actualization repeatedly (21–23). Walter Benjamin (1892–1940) is the framing intellectual influence for this study, especially his writings about children during the 1920s and 1930s. He saw the child’s imaginative expressiveness, unconventionality, and ability to yoke disparate images as possessing not only critical but also radically revolutionary potential. Ulanowicz, to put it [End Page 286] simply, hopes that under the right circumstances the child listener’s or reader’s critical consciousness is stimulated to ask questions and therewith begin the process of change that may eventually be accepted by the collective will of the community. Though the last Armenian genocide had occurred during the Great War, Benjamin’s writings were completed before the age of atrocities began in Europe and his influence, belated as it is in the European and American context, cannot be considered as an emerging theory of memory. Furthermore, Ulanowicz does not acknowledge the potential propaganda value of Benjamin’s observations and theories. As long as children knew which side was “the right side,” German fascism and Soviet communism encouraged and radicalized children to question and critique. There is a rather romantic projection of the child’s primary impulses and spontaneity in Benjamin’s writing on this subject that Ulanowicz modifies. She sees the child, protagonist or reader, empathetically, critically, and creatively active as she or he absorbs and reenvisions memories conveyed by witness-survivors or by cultural media...

Periarticular Osteoid Osteoma of the Ankle: A Report of Nine Arthroscopically Treated Patients

Periarticular osteoid osteoma often presents with unspecific clinical symptoms, mimicking other clinical conditions. This can lead a clinician to a ''diagnostic side path'' and a delayed or missed diagnosis compared with extra-articular osteoid osteoma. We report the cases of 9 patients with a mean age of 22 (range 14 to 32) years who were diagnosed with periarticular osteoid osteoma of the ankle and were surgically treated in our department during a 12-year period. The diagnostic difficulties associated with periarticular osteoid osteoma must be resolved by obtaining a detailed patient history and performing a thorough physical examination. Computed tomography is the ultimate imaging method to confirm the suspicion of osteoid osteoma. Arthroscopic removal of the osteoid osteoma was performed in all 9 patients in the present case series, with synovectomy performed when indicated. Under arthroscopic visualization, a specimen was obtained for histopathologic analysis to confirm the diagnosis, followed by tumor excision. All the patients were pain free at the final follow-up visit after a mean duration of 6 years (range 6 months to 12.7 years) postoperatively. We suggest arthroscopic removal of periarticular osteoid osteomas of the ankle as an effective treatment method, because it allows complete tumor excision, synovectomy when needed, a short postoperative rehabilitation period, and satisfactory functional results.

Straight-chain alkyl isocyanides open the distal histidine gate in crystal structures of myoglobin .

Crystal structures of methyl, ethyl, propyl, and butyl isocyanide bound to sperm whale myoglobin (Mb) reveal two major conformations. In the in conformer, His(E7) is in a "closed" position, forcing the ligand alkyl chain to point inward. In the out conformer, His(E7) is in an "open" position, allowing the ligand side chain to point outward. A progressive increase in the population of the out conformer is observed with increasing ligand length in P2(1) crystals of native Mb at pH 7.0. This switch from in to out with increasing ligand size also occurs in solution as measured by the decrease in the relative intensity of the low-frequency ( approximately 2075 cm(-1)) versus high-frequency ( approximately 2125 cm(-1)) isocyano bands. In contrast, all four isocyanides in P6 crystals of wild-type recombinant Mb occupy the in conformation. However, mutating either His64 to Ala, creating a "hole" to solvent, or Phe46 to Val, freeing rotation of His64, causes bound butyl isocyanide to point completely outward in P6 crystals. Thus, the unfavorable hindrance caused with crowding a large alkyl side chain into the distal pocket appears to be roughly equal to that for pushing open the His(E7) gate and is easily affected by crystal packing. This structural conclusion supports the "side path" kinetic mechanism for O(2) release, in which the dissociated ligand first moves toward the protein interior and then encounters steric resistance, which is roughly equal to that for escaping to solvent through the His(E7) channel.

Effect of zinc and cadmium ions on structure and function of myoglobin

Laser flash photolysis technique was used to study zinc and cadmium ion effects on bimolecular and nanosecond geminate molecular oxygen (O 2) rebinding to horse heart myoglobin. Time courses for geminate recombination are analyzed in terms of a three-step, side path model. In the presence of metal ions, the greatest changes are observed in the rate constant of the O 2 rebinding from within the primary docking site and the rate constant of the O 2 migration from the primary site to the secondary xenon docking sites. The study revealed that modulation of the myoglobin affinity for O 2 by zinc and cadmium occurs at the level of the innermost barrier controlling O 2 rebinding from within the primary docking site. Sets of the calculated rate constants provide a basis for an interpretation of metal ion effects on the myoglobin structure. Overall, the results demonstrate that the metal ions binding to myoglobin gives rise to an increase in the population of the “open” distal pocket protein conformation.

Ligand pathways in myoglobin: A review of trp cavity mutations

The pathways for ligand entry and exit in myoglobin have now been well established by a wide variety of experimental results, including pico- to nano- to microsecond transient absorbance measurements and time-resolved X-ray crystallographic measurements. Trp insertions have been used to block, one at a time, the three major cavities occupied by photodissociated ligands. In this work, we review the effects of the L29(B10)W mutation, which places a large indole ring in the initial 'docking site' for photodissociated ligands. Then, the effects of blocking the Xe4 site with I28W, V68W, and I107W mutations and the Xe1 cavity with L89W, L104W, and F138W mutations are described. The structures of four of these mutants are shown for the first time (Trp28, Trp68, Trp107, and Trp 138 sperm whale metMb). All available results support a 'side path' mechanism in which ligands move into and out of myoglobin by outward rotation of the HisE7 side chain, but after entry can migrate into internal cavities, including the distal Xe4 and proximal Xe1 binding sites. The distal cavities act like the pocket of a baseball glove, catching the ligand and holding it long enough for the histidine gate to close and facilitate internal coordination with the heme iron atom. The physiological role of the proximal Xe1 site is less clear because changes in the size of this cavity have minimal effects on overall O(2) binding parameters.

Embedded internet for hearing aids

A method is described to operate a hearing device with an input transducer ( 1 ), a signal processing unit ( 2 ) and an output transducer ( 4 ). The method comprises the steps of converting an acoustic input signal into a converted input signal, processing the converted input signal in a main signal path in order to obtain a main output signal, and supplying the main output signal to an output transducer. By processing the converted input signal in a side signal path to obtain a side path output signal, and by superimposing the side path output signal on the main output signal, wherein a group delay of a signal traveling through the side signal path is smaller than a group delay of a signal traveling through the main signal path, the localization problems are eliminated. At the same time, the hearing device according to the present invention can still have a very high performance. In short terms, a “zero-delay-high-performance” hearing device has been created by the present invention.

Influence of Zinc Ions on the Geminal and Bimolecular Stages of the Horse-Myoglobin Oxygenation

The kinetics of nanosecond geminal recombination and bimolar association of molecular oxygen with the horse-heart myoglobin has been investigated by laser flash photolysis. The influence of Zn(II) ions on the dioxygenation and rebonding of myoglobin to a ligand has been considered. The kinetics of the geminal recombination was analyzed within the framework of the model of four states with a side path of ligand motion in the protein matrix. It is shown that an increase in the affinity of myoglobin to O2 in the presence of Zn(II) ions is predominantly caused by an increase in the rate constant of recombination of molecular oxygen from the primary intraprotein site.

Fourier transform infrared difference spectroscopy of photosystem II tyrosine D using site-directed mutagenesis and specific isotope labeling.

Tyrosine D (TyrD), a side path electron carrier of photosystem II (PS II), has been studied by light-induced Fourier transform infrared (FTIR) difference spectroscopy in PS II core complexes of Synechocystis sp. PCC 6803 using the experimental conditions previously optimized to generate the pure TyrD./TyrD FTIR difference spectrum in PS II-enriched membranes of spinach [Hienerwadel, R., Boussac, A., Breton, J., and Berthomieu, C. (1996) Biochemistry 35, 115447-115460]. IR modes of TyrD and TyrD. have been identified by specific 2H- or 13C-labeling of the tyrosine side chains. The v8a(CC) and v19(CC) IR modes of TyrD are identified at 1615 and 1513-1510 cm-1, respectively. These frequencies show that TyrD is protonated. Comparison of isotope-sensitive signals in situ with those of the model compound p-methylphenol dissolved in different solvents leads to the assignment of the v7'a(CO) and delta(COH) modes of TyrD at 1275 and 1250 cm-1, respectively. It is shown that these modes and in particular the delta(COH) IR mode are very sensitive to the formation of hydrogen-bonded complexes with amide C=O or with imidazole nitrogen atoms. The frequencies observed in situ show that TyrD is hydrogen-bonded to the imidazole ring of a neutral histidine. For the radical TyrD., isotope-sensitive IR modes are identified at 1532 and 1503 cm-1. The signal at 1503 cm-1 is assigned to the v(CO) mode of TyrD. since it is sensitive to 13C-labeling at the ring carbon involved in the C4-O bond. The perturbation of TyrD and TyrD. IR modes upon site-directed replacement of D2-His189 by Gln confirms that a hydrogen bond exists between both TyrD and TyrD. and D2-His189. In the D2-His189Gln mutant, the v7'a(CO) mode of TyrD at 1267 cm-1 and the delta(COH) mode at approximately 1228 cm-1 show that a hydrogen bond is formed between TyrD and an amide carbonyl, probably that of the D2-Gln189 side chain. Electron nuclear double resonance (ENDOR) measurements have shown that TyrD. is hydrogen-bonded in the wild type but not in the mutant [Tang, X.-S., Chrisholm, D. A., Dismukes, G. C., Brudwig, G. W., and Diner, B. A. (1993) Biochemistry 32, 13742-13748]. The v(CO) mode of TyrD. at 1497 cm-1 is downshifted by 6 cm-1 compared to WT PS II, indicating that hydrogen bonding induces a frequency upshift of the v(CO) IR mode of Tyr.. IR signals from the Gln side chain v(C=O) mode are proposed to contribute at 1659 and 1692 cm-1 in the TyrD and TyrD. states, respectively. These frequencies are consistent with the rupture of a hydrogen bond upon TyrD. formation in the mutant. The frequency of the v(CO) mode of TyrD., observed at 1503 cm-1 for WT PS II, is intermediate between that observed at 1497 cm-1 in the D2-His189Gln mutant and at 1513 cm-1 for Tyr. formed by UV irradiation in borate buffer, suggesting weaker or fewer hydrogen bonds for TyrD. in PS II than in solution. The role of D2-His189 in proton uptake upon TyrD. formation is also investigated.

Metal Ion Promoted Hydrolysis of Polyphosphates

Various CoIII amine aqua hydroxo complexes have been evaluated for their ability to hydrolyse pyrophosphate to phosphate rapidly. Two very effective reagents have emerged, [Co( trpn )(OH)(OH2)]2+ ( trpn = 3,3′,3″-nitrilotris(propan-1-amine)) and [Co( tamen )(OH)-OH2)]2+ ( tamen = 6-(4-amino-2-azabutyl)-6-methyl-1,4-diazacycloheptane), and the latter has been examined closely to assess details of the mechanistic path for hydrolysis. The study shows substitution of the reagent on the substrate is fast and not rate determining. Two moles of the reagent are required to bind to [(en)2Co(P2O7)]- (en = ethane-1,2-diamine) to effect rapid hydrolysis. One supplies the coordinated OH- nucleophile to cleave the phosphorus anhydride, and the other binds as a chelate to the leaving group to assist bond rupture. An unproductive side path, to form a symmetrical dichelate of the form [(en)2Co(P2O7)Co( tamen )]2+, becomes rate limiting. However, if this path can be reduced in significance or eliminated, the study implies that polyphosphates and phosphate esters should hydrolyse on the subsecond time scale.

Pb 2+ and imidazole-activated phosphorylation by ATP of [formula omitted

In order to study whether Pb 2+ and imidazole increase the ATP phosphorylation level of ( Na + + K +)- ATPase by the same mechanism, the effects of both compounds on phosphorylation and dephosphorylation reactions of the enzyme have been studied. Imidazole in the presence of Mg 2+ increases steady-state phosphorylation of ( Na + + K +)- ATPase by decreasing, in a competitive way, the K +-sensitivity of the formed phosoho-enzyme ( E-P · Mg ). If Pb 2+ is present during phosphorylation, the rate of phosphorylation increases and a K +- and ADP-insensitive phosphointermediate ( E-P · Pb ) is formed. Pb 2+ has no effect on the K +-sensitivity of E-P · Mg and EDTA is unable to affect the K +-insensitivity of E-P · Pb . These effects indicate that Pb 2+ acts before or during phosphorylation with the enzyme. Binding of Na + to E-P · Pb does not restore K +-sensitivity either. However, increasing Na + during phosphorylation in the presence of Pb 2+ leads to formation of the K +-sensitive intermediate ( E-P · Mg ), indicating that E-P · Pb is formed via a side path of the Albers-Post scheme. ATP and ADP decrease the dephosphorylation rate of both E-P · Mg and E-P · Pb . Above optimal concentration, Pb + also decreases the steady-state phosphorylation level both in the absence and in the presence of Na +. This inhibitory effect of Pb 2+ is antagonized by Mg 2+.

Ultrasonic liquid level meter

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