scholarly journals Analog Electronic Circuits to Model Cooperativity in Hill Process

2020 ◽  
Vol 39 (4) ◽  
pp. 678-685
Author(s):  
Maria Waqas ◽  
Muhammad Khurram ◽  
S.M. Razaul Hasan
Keyword(s):  
Chemical Reactions ◽  
Electronic Circuit ◽  
Main Idea ◽  
Receptor Site ◽  
The Other ◽  
Hill Reaction ◽  
Cellular Processes ◽  
Receptor Sites ◽  
Model Dynamics ◽  
The Hill

In the field of computational biology, electronic modeling of bio-cellular processes is in vogue for about a couple of decades. Fast, efficient and scalable electronic mimetics of recurrently found bio-chemical reactions are expected to provide better electronic circuit simulators that can also be used as bio-sensors or implantable biodevices at cellular levels. This paper presents some possible electronic circuit equivalents to model dynamics of one such bio-chemical reaction commonly involved in many bio-cellular processes, specifically pathways in living cells, known as the Hill process. The distinguishing feature of this process is cooperativity which has been modeled in silicon substrate using a pair of transistors, one transistor driving current in the other the same way ligand binding to one receptor site controls the binding affinity of the other receptor sites. Two possible circuits have been proposed and compared to electronically model cooperativity of a Hill reaction. The main idea is to exploit the natural analogies found between structures and processes of a bio-cell and electronic transistor mechanics, to efficiently model fundamental bio-chemical reactions found recurring in bio-processes. These circuits can then be combined and rearranged quickly to form larger, more complex bio-networks, thus mitigating the intricacies involved in modeling of such systems.

Cyanoacrylate Inhibitors of the Hill Reaction V. The Effect of Chirality on Inhibitor Binding

1987 ◽  
Vol 42 (6) ◽  
pp. 684-689 ◽  
Author(s):  
John L. Huppatz ◽  
John N. Phillips
Keyword(s):  
Phenyl Ring ◽  
Alkyl Substituent ◽  
Receptor Site ◽  
Optically Active ◽  
Hill Reaction ◽  
Inhibitor Binding ◽  
Level Of Activity ◽  
The Difference ◽  
The Hill

Optically active α-methylbenzylamino 2-cyanoacrylic esters were synthesized and assayed as inhibitors of the Hill reaction in isolated pea chloroplast fragments. The 5-isomers were more potent inhibitors than the S-isomers with discriminations of from ten to greater than 100-fold being observed. A β-alkyl substituent in the cyanoacrylate molecule affected both the level of activity and the difference in activity between the isomers. An α,α-dimethylbenzylamino derivative was also active at about the same level as the corresponding α-methylbenzylamino racemate. This result could be explained in terms of the orientation of the phenyl ring in the receptor site. Replacement of the α-methylbenzylamino group by other α-alkyl and α-phenyl substituents had little effect on activity. However, an α-benzyl group was beneficial.

Effect of Temperature on Photoreductive Activity of Chloroplasts From Passionfruit Species of Different Chilling Sensitivity

1978 ◽  
Vol 5 (4) ◽  
pp. 443 ◽  
Author(s):  
C Critchley ◽  
RM Smillie ◽  
BD Patterson
Keyword(s):  
Heat Stability ◽  
The Other ◽  
Effect Of Temperature ◽  
Tropical Species ◽  
Clear Correlation ◽  
Hill Reaction ◽  
Resistant Species ◽  
Chilling Sensitivity ◽  
Cold Tolerant ◽  
The Hill

The Hill reaction activity of chloroplast membranes isolated from five Passiflora species of different chilling sensitivity was determined as a function of temperature over the range 0 - 40°C. Activity was measured by the photoreduction of ferricyanide in the presence of gramicidin D. In two lowland tropical and chilling-sensitive species, P. quadrangularis and P. edulis forma flavicarpa, the apparent Arrhenius activation energy (Ea) for ferricyanide photoreduction was more than doubled at temperatures below 16 and 10°C, respectively. This increase in Ea was also characteristic of more chilling- resistant species. P. cincinnata, which is intermediate in chilling sensitivity between the two lowland tropical and the other two species studied, showed an increase in Ea below 15°C. A hybrid of this species with P. edulis forma flavicarpa behaved similarly. In chloroplasts from P. edulis, a species relatively resistant to chilling temperatures, there was an increase in Ea below 16°C, like that shown by P. quadrangularis, as well as another increase below 4°C. P. caerulea, the most chilling-resistant of the species studied, showed changes in Ea at 7 and 19°C. Thus, there was no clear correlation between the chilling sensitivity or resistance of a species and the presence or absence of a change in the temperature dependence of the Hill activity at low temperatures. The heat stability of the photoreductive activity of chloroplasts isolated from the various Passiflora species also did not correlate with their chilling sensitivity. The heat stability of photoreductive activity in the most cold-tolerant species, P. caerulea, was comparable with that found for the tropical species, while chloroplasts from P. cincinnata were more heat-labile than chloroplasts from the other species.

Stereospecific Inhibitor Probes of the PS II Herbicide Binding Site

1987 ◽  
Vol 42 (6) ◽  
pp. 674-678 ◽  
Author(s):  
John L. Huppatz ◽  
John N. Phillips
Keyword(s):  
Phenyl Ring ◽  
Receptor Site ◽  
Spatial Arrangement ◽  
Hill Reaction ◽  
Hydrophobic Region ◽  
Inhibitor Molecule ◽  
Ps Ii ◽  
Hydrophobic Domain ◽  
The Difference ◽  
The Hill

The influence of steric factors on the activity of 2-cyanoacrylic esters as inhibitors of the Hill reaction was examined. The spatial arrangement of the different groups in the inhibitor molecule was found to be an important factor in determining potency. The positioning of the phenyl ring in aralkylamino derivatives and the steric properties of the β-substituent are particularly significant in the interaction of molecules with the) hydrophobic domain of the receptor site. The difference in activity observed with optically active α-methylbenzylamino derivatives confirmed the importance of the orientation of the phenyl ring and indicated an interaction with a specific hydrophobic region.

Morrison's Beloved and its Two "Amadas": Postcolonial Signifying upon Translation within African-American Intertextualities

1969 ◽  
Author(s):  
José Endoença Martins
Keyword(s):  
African American ◽  
Main Idea ◽  
Black Nationalism ◽  
The Other ◽  
Source Text ◽  
Specific Source ◽  
Theoretical Foundations ◽  
Specific Concern

This article compares two different Brazilian translated versions of Toni Morrison's novel Beloved: the first published in 1994, the other in 2007, both as Amada. The analysis concentrates on the speech delivered by Baby Suggs, in which she exhorts her listeners to care for their bodies. The main idea behind this article is that Beloved and the Amadas converse or talk, thus performing signifyin(g), a concept which, in Henry Louis Gates's words, explains how intertextual conversation happens through “repetition and revision, or repetition with a signal of difference” (xxiv). Its general theoretical foundations include interconnections involving several instantiations of signifyin(g): between Black nationalism and negritude, postcolonialism and African Americanism. In its specific concern with translation, the conversation that the source keeps with the target texts involves two translation theories: fluency and resistance; two kinds of translating interventions: omission and addition; and three types of strategies: syntactic, semantic, and pragmatic. These distinct categories help readers grasp translation as a continuum by means of which a specific source text encounters its target equivalents and, then, returns to its origin. The original article is in English.

The Germans and Air Power at Dieppe: The Raid and its Lessons from the ‘Other Side of the Hill’

2021 ◽  
pp. 096834452199586
Author(s):  
James Shelley
Keyword(s):  
Armed Forces ◽  
The Other ◽  
Air Power ◽  
Coastal Defence ◽  
German Armed Forces ◽  
Popular Interest ◽  
The Hill

Despite the vast academic and popular interest in the Dieppe raid of 19 August 1942, there remains a curious oversight of the German side of the story. This contribution interrogates German sources in order to explore the Dieppe air battle and its consequences from the perspective of the German armed forces. The paper ultimately demonstrates that the Germans learnt much about the role of air power in coastal defence from their experiences at Dieppe, but that the implementation of those lessons was lacking.

scholarly journals Transposition Pattern of the Maize Element Ac from the Bz-M2(ac) Allele.

Genetics ◽  
1989 ◽  
Vol 122 (2) ◽  
pp. 447-457 ◽  
Author(s):  
H K Dooner ◽  
A Belachew
Keyword(s):  
Donor Site ◽  
Receptor Site ◽  
Receptor Sites ◽  
Mutable Allele ◽  
Ac Transposition ◽  
P Locus

Abstract The pattern of transposition of Ac from the mutable allele bz-m2(Ac) has been investigated. Stable (bz-s) and finely spotted (bz-m(F)) exceptions were selected from coarsely spotted bz-m2(Ac) ears. The presence or absence of a transposed Ac (trAc) in the genome was determined and, when present, the location of the trAc was mapped relative to the flanking markers sh and wx. The salient general features of Ac transposition to sites linked to bz are that the receptor sites tend to be clustered on either side of the bz donor site and that transposition is bidirectional and nonpolar. Thus, the symmetrical clustering in the distribution of receptor sites adjacent to bz differs from the asymmetrical clustering reported in 1984 for the P locus by I. M. GREENBLATT. Though Ac tends to transpose preferentially to closely linked sites, an appreciable fraction of Ac transpositions from bz-m2(Ac) is to unlinked sites: 41% among bz-s derivatives and 59% among bz-m(F) derivatives. Many transposition events among the bz-m(F) selections result in kernels carrying a genetically noncorresponding embryo. These can be interpreted as twin sectors arising at one of the megagametophytic mitoses. The bz locus data fit the earlier (1962) model of I. M. GREENBLATT and R. A. BRINK in which transposition takes place from a replicated donor site to either an unreplicated or replicated receptor site.

Interaction of Photosystem II Herbicides with Bicarbonate and Formate in Their Effects on Photosynthetic Electron Flow

1984 ◽  
Vol 39 (5) ◽  
pp. 374-377 ◽  
Author(s):  
J. J. S. van Rensen
Keyword(s):  
Electron Transport ◽  
Photosystem Ii ◽  
Electron Flow ◽  
Photosynthetic Electron Transport ◽  
Hill Reaction ◽  
Amaranthus Hybridus ◽  
Apparent Affinity ◽  
Photosynthetic Electron Flow ◽  
Different Characteristics ◽  
The Hill

The reactivation of the Hill reaction in CO2-depleted broken chloroplasts by various concentrations of bicarbonate was measured in the absence and in the presence of photosystem II herbicides. It appears that these herbicides decrease the apparent affinity of the thylakoid membrane for bicarbonate. Different characteristics of bicarbonate binding were observed in chloroplasts of triazine-resistant Amaranthus hybridus compared to the triazine-sensitive biotype. It is concluded that photosystem II herbicides, bicarbonate and formate interact with each other in their binding to the Qв-protein and their interference with photosynthetic electron transport.

Metabolism of a Pyrrolidine Urea Herbicide in Corn and Weeds

Weed Science ◽  
1974 ◽  
Vol 22 (1) ◽  
pp. 10-14 ◽  
Author(s):  
R. E. Holm ◽  
D. E. Stallard
Keyword(s):  
Adventitious Roots ◽  
Parent Compound ◽  
Soil Surface ◽  
Abutilon Theophrasti ◽  
Water Soluble ◽  
Hill Reaction ◽  
Panicum Miliaceum ◽  
Proso Millet ◽  
Ipomoea Purpurea ◽  
The Hill

Five 2,5-dimethyl-1-pyrrolidinecarboxanilides were effective inhibitors of the Hill reaction. However, only thecisisomers were active; thetransisomers were totally inactive. Experiments were conducted using14C-5328 (cis-2,5-dimethyl-1-pyrrolidinecarboxanilide). A correlation existed between resistance of various plants to 5328 and their ability to metabolize it to water soluble metabolites. Velvetleaf (Abutilon theophrastiMedic.) and proso millet (Panicum miliaceumL.) seedlings were very susceptible to 5328 and were unable to metabolize it. Tall morningglory [Ipomoea purpurea(L.) Roth] seedlings were highly tolerant to 5328 and converted it completely to its metabolites. Corn (Zea maysL. ‘DeKalb variety XL-45′) seedlings which were slightly susceptible to 5328 injury were able to metabolize up to 90% of the parent compound. Corn foliage uptake of14C-5328 applied to the soil surface occurred through the adventitious roots.

scholarly journals Studies on the Second Emerson Effect in the Hill Reaction in Algal Cells

1961 ◽  
Vol 1 (5) ◽  
pp. 377-388 ◽  
Author(s):  
Rajni Govindjee ◽  
Eugene Rabinowitch
Keyword(s):  
Hill Reaction ◽  
The Hill
Sign in / Sign up

Export Citation Format

Share Document