scholarly journals THE ROLE OF BIVALENT CATIONS IN INTERACTION BETWEEN ACTOMYOSIN AND ADENOSINE TRIPHOSPHATE AT LOW IONIC STRENGTH

1965 ◽  
Vol 15 (3) ◽  
pp. 211-223
Author(s):  
Hideo TAKASHINA ◽  
Minoru KASUYA
Keyword(s):  
Ionic Strength ◽  
Adenosine Triphosphate ◽  
Bivalent Cations ◽  
Low Ionic Strength

Gastropod predation sites: the role of predator and prey in chemical attraction of the hermit crab Clibanarius vittatus

1990 ◽  
Vol 70 (3) ◽  
pp. 583-596 ◽  
Author(s):  
D. Rittschof ◽  
C.M. Kratt ◽  
A.S. Clare
Keyword(s):  
Salivary Gland ◽  
Ionic Strength ◽  
Salivary Glands ◽  
Hermit Crab ◽  
Sea Water ◽  
Hermit Crabs ◽  
Muscle Proteins ◽  
Clibanarius Vittatus ◽  
Low Ionic Strength

Gastropod shells are essential to most hermit crabs. Shell availability limits hermit crab populations. Shells provide protection and the degree of shell-fit controls crab growth and fecundity. Crabs locate new gastropod shells from a distance under water by molecules released from gastropod flesh during predation events. Here we test the hypothesis that the salivary glands of the predatory gastropod are the source of enzymes that digest muscle proteins and release peptide attractants. We describe the anatomy of both the acinous salivary glands and the tubular accessory salivary glands of Busycon contrarium which are similar to those of B. carica. The salivary gland ducts empty at the mouth, suggesting a role in the primary digestion of food. We show that gastropod muscle proteins, extracted by salt solutions with the ionic strength of sea water and purified by precipitation in low ionic strength can be digested by gastropod salivary gland enzymes to generate peptides attractive to the hermit crab, Clibanarius vittatus, in field assays.

Structure Optimization in Colloidal Reinforcing Fillers: Precipitated Silica

2002 ◽  
Vol 75 (5) ◽  
pp. 773-794 ◽  
Author(s):  
Dale W. Schaefer ◽  
Chunyan Chen
Keyword(s):  
Ionic Strength ◽  
Solution Synthesis ◽  
Precipitated Silica ◽  
Reinforcing Fillers ◽  
Primary Particles ◽  
Reinforcement Model ◽  
Low Ionic Strength ◽  
Light And Neutron Scattering ◽  
The Ideal

Abstract In an attempt to elucidate the role of filler morphology in elastomer reinforcement, we use x-ray, light and neutron scattering to determine the structure of precipitated silica powders. We find the signatures of at least three levels of structure: primary particles, aggregates and agglomerates. By observing the evolution of the scattering profile during solution synthesis, we are able to identify when these structures appear. We also investigate the effect of ionic strength on morphology and find evidence for the interpenetration of aggregates on drying of powders prepared at low ionic strength. Using a reinforcement model by Witten, Rubinstein and Colby, we conclude that the ideal filler will consist of soft agglomerates made up of hard aggregates. Based on the dependence of morphology on synthetic protocol, we present strategies for design of efficient reinforcing fillers.

Expression in Escherichia coli of fragments of the coiled-coil rod domain of rabbit myosin: influence of different regions of the molecule on aggregation and paracrystal formation

1991 ◽  
Vol 99 (4) ◽  
pp. 823-836
Author(s):  
S.J. Atkinson ◽  
M. Stewart
Keyword(s):  
Escherichia Coli ◽  
Ionic Strength ◽  
Coiled Coil ◽  
Periodic Variation ◽  
Heptad Repeat ◽  
C Terminus ◽  
N Terminus ◽  
Low Ionic Strength ◽  
Myosin Rod

We have expressed in Escherichia coli a cDNA clone corresponding broadly to rabbit light meromyosin (LMM) together with a number of modified polypeptides and have used this material to investigate the role of different aspects of molecular structure on the solubility properties of LMM. The expressed material was characterized biochemically and structurally to ensure that it retained the coiled-coil conformation of the native molecule. Full-length recombinant LMM retained the general solubility properties of myosin and, although soluble at high ionic strength, precipitated when the ionic strength was reduced below 0.3 M. Constructs in which the ‘skip’ residues (that disrupt the coiled-coil heptad repeat) were deleted had solubility properties indistinguishable from the wild type, which indicated that the skip residues did not play a major role in determining the molecular interactions involved in assembly. Deletions from the N terminus of LMM did not alter the solubility properties of the expressed material, but deletion of 92 residues from the C terminus caused a large increase in solubility at low ionic strength, indicating that a determinant important for interaction between LMM molecules was located in this region. The failure of deletions from the molecule's N terminus to alter its solubility radically suggested that the periodic variation of charge along the myosin rod may not be as important as proposed for determining the strength of binding between molecules and thus the solubility of myosin.

scholarly journals Effects of deletion of tropomyosin overlap on regulated actomyosin subfragment 1 ATPase

1989 ◽  
Vol 258 (3) ◽  
pp. 831-836 ◽  
Author(s):  
D H Heeley ◽  
L B Smillie ◽  
E M Lohmeier-Vogel
Keyword(s):  
Ionic Strength ◽  
Binding Model ◽  
Thin Filaments ◽  
System A ◽  
Atpase Assay ◽  
Myosin Subfragment ◽  
Myosin Subfragment 1 ◽  
Low Ionic Strength ◽  
Atpase Inhibition

The role of the overlap region at the ends of tropomyosin molecules in the properties of regulated thin filaments has been investigated by substituting nonpolymerizable tropomyosin for tropomyosin in a reconstituted troponin-tropomyosin-actomyosin subfragment 1 ATPase assay system. A previous study [Heeley, Golosinka & Smillie (1987) J. Biol. Chem. 262, 9971-9978] has shown that at an ionic strength of 70 mM, troponin will induce full binding of nonpolymerizable tropomyosin to F-actin both in the presence and absence of calcium. At a myosin subfragment 1-to-actin ratio of 2:1 ([actin] = 4 microM) and an ionic strength of 50 mM, comparable levels of ATPase inhibition were observed with increasing levels of tropomyosin or the truncated derivative in the presence of troponin (-Ca2+). Large differences were noted, however, in the activation by Ca2+. Significantly lower ATPase activities were observed with nonpolymerizable tropomyosin and troponin (+Ca2+) over a range of subfragment 1-to-actin ratios from 0.25 to 2.5. The concentration of subfragment 1 required to generate ATPase activities exceeding those seen with actomyosin subfragment 1 alone under these conditions was 3-4-fold greater when nonpolymerizable tropomyosin was used. Similar effects were seen at the much lower ionic strength of 13 mM and are consistent with the reduced ATPase activity with nonpolymerizable tropomyosin observed previously [Walsh, Trueblood, Evans & Weber (1985) J. Mol. Biol. 182, 265-269] at low ionic strength and a subfragment 1-to-actin ratio of 1:100. Little cooperativity in activity as a function of subfragment 1 concentration with either intact tropomyosin or its truncated derivative was observed under the present conditions. Further studies are directed towards an understanding of these effects in terms of the two-state binding model for the attachment of myosin heads to regulated thin filaments.

scholarly journals Role of divalent cations on DNA polymorphism under low ionic strength conditions

1986 ◽  
Vol 14 (12) ◽  
pp. 5099-5109 ◽  
Author(s):  
Sundaram Devarajan ◽  
Richard H. Shafer
Keyword(s):  
Ionic Strength ◽  
Dna Polymorphism ◽  
Divalent Cations ◽  
Low Ionic Strength

ROLE OF TAMM-HORSFALL PROTEIN (THP) IN LITHOGENIC PROCESS : ANIMAL STUDIES

2019 ◽  
pp. 1-2
Author(s):  
Varsha Choudhary
Keyword(s):  
Ionic Strength ◽  
Guinea Pigs ◽  
Animal Studies ◽  
Dual Role ◽  
Urinary Oxalate ◽  
Crystal Aggregation ◽  
Physico Chemical ◽  
Low Ionic Strength

One of the defenses against nephrolithiasis is provided by macromolecules that modulate the nucleation, growth, aggregation and retention of crystals in the kidneys.According to its well-known physico-chemical properties.THP has a dual role in modifying crystal aggregation: at high pH and low ionic strength (IS),THP is a powerful crystal aggregation inhibitor.Upon lowering pH and rasing ionic strength THP viscosity increases,leading to reduced crystal aggregation inhibition.For this purpose eight guinea pigs were made hyperoxaluric.The treatment was given for fifteen days;then urine samples were collected before treatment ;then on 5,10,15and 25 day( after treatment) and in vitro addition of THP on 30th day which was isolated from hyperoxaluric and normal animals.The effect of EG+GM on urinary oxalate,THP and TBAR levels increases but after treatment the urine chemistry revert to normal profile,though plasma TBAR levels were appreciably high.The crystallization of calcium was almost double when THP was isolated from hyperoxaluric animals rather than normals.Our study suggested that THP act as a promoter

Role of Heavy Meromyosin in Heat-Induced Gelation in Low Ionic Strength Solution Containingl-Histidine

2015 ◽  
Vol 80 (8) ◽  
pp. C1641-C1645 ◽  
Author(s):  
Toru Hayakawa ◽  
Yuri Yoshida ◽  
Masanori Yasui ◽  
Toshiaki Ito ◽  
Jun-ichi Wakamatsu ◽  
...  
Keyword(s):  
Ionic Strength ◽  
Heavy Meromyosin ◽  
Low Ionic Strength
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