Imidazole catalyzed silica synthesis: Progress toward understanding the role of histidine in (bio)silicification

2009 ◽  
Vol 24 (5) ◽  
pp. 1700-1708 ◽  
Author(s):  
Mei-Keat Liang ◽  
Siddharth V. Patwardhan ◽  
Elena N. Danilovtseva ◽  
Vadim V. Annenkov ◽  
Carole C. Perry
Keyword(s):  
Molecular Weight ◽  
Silicic Acid ◽  
Catalytic Mechanism ◽  
Synthetic Polymers ◽  
Precipitation Process ◽  
Silica Precipitation ◽  
Silica Synthesis ◽  
Different Molecular Weight

Histidine is an amino acid present in proteins involved in biosilica formation and often found in peptides identified during phage display studies but its role(s) and the extent of its involvement in the silica precipitation process is not fully understood. In this contribution we describe results from an in vitro silicification study conducted using poly-histidine (P-His) and a series of different molecular weight synthetic polymers containing the imidazole functionality (polyvinylimidazole, PVI) for comparison. We show that the presence of imidazole from PVI or P-His is able to catalyze silicic acid condensation; the effect being greater for P-His. The catalytic mechanism is proposed to involve the dual features of the imidazole group—its ability to form hydrogen bonds with silicic acid and electrostatic attraction toward oligomeric silicic acid species.

The role of small molecular weight compounds to increase vacuolation induced by VacA toxin in vitro

2010 ◽  
Vol 24 (5) ◽  
pp. 1373-1378 ◽  
Author(s):  
Juan Sun ◽  
Yan Wu ◽  
Zhuang Su ◽  
Zhifang Liu ◽  
Bingzhong Su ◽  
...  
Keyword(s):  
Molecular Weight ◽  
Small Molecular Weight

THE ROLE OF ADSORPTION IN CONTROLLING THE RATE OF REACTION OF CHLORAMBUCIL WITH PROTEIN

1963 ◽  
Vol 41 (4) ◽  
pp. 931-939 ◽  
Author(s):  
J. H. Linford
Keyword(s):  
Molecular Weight ◽  
Carboxylic Acid ◽  
Bovine Serum Albumin ◽  
Inverse Relationship ◽  
Reaction Rate ◽  
The Other ◽  
Alkylation Reaction ◽  
Rate Of Reaction

Two proteins, haemoglobin and bovine serum albumin, have been studied with respect to their rates of alkylation by chlorambucil in vitro at 37 °C and pH 8.4. The proteins are of nearly the same molecular weight and free carboxylic acid content, but the alkylation reaction is 30 times faster with haemoglobin. On the other hand, the adsorption of chlorambucil by albumin is 20 times greater than that exhibited by haemoglobin. This inverse relationship between extent of adsorption and reaction rate suggests that adsorption protects the chlorambucil from activation in the solvent.

Studies on the Role of Fibrinolysis and Fibrinogen Degradation Products (FDP) in Analgesic Action of Morphine

1972 ◽  
Vol 28 (03) ◽  
pp. 359-366 ◽  
Author(s):  
Włodzimierz Buczko ◽  
Konstanty Wiśniewski
Keyword(s):  
Molecular Weight ◽  
Brain Tissue ◽  
Clinical Effect ◽  
Degradation Products ◽  
Analgesic Action ◽  
Fibrinogen Degradation Products ◽  
The Brain

SummaryThe role of fibrinolysis and FDP in the analgesic action of morphine in mice and rats was studied. It was shown that during activation of blood fibrinolysis, both the accumulation of morphine in the brain tissue of rats and the clinical effect of this drug were increased. Similar results were observed after morphine given simultaneously with FDP obtained in vitro. The data from the analysis of FDP carried out on Sephadex G-25 Fine columns suggest that only FDP of molecular weight of about 10,000 potentiate the action of morphine; smaller peptides decreased the action of this drug.

Analysis of the Action of Quaternized Chitosans with Different Molecular Weight on Anticoagulant Activity of Heparins In Vitro

2019 ◽  
Vol 167 (2) ◽  
pp. 279-283 ◽  
Author(s):  
N. N. Drozd ◽  
Yu. S. Logvinova ◽  
B. Ts. Shagdarova ◽  
A. V. Il’ina ◽  
V. P. Varlamov
Keyword(s):  
Molecular Weight ◽  
Anticoagulant Activity ◽  
Different Molecular Weight

The role of hemolysate in the facilitation of oxyhemoglobin-induced contraction in rabbit basilar arteries

1994 ◽  
Vol 81 (2) ◽  
pp. 261-266 ◽  
Author(s):  
Toshiki Aoki ◽  
Katsunobu Takenaka ◽  
Satoshi Suzuki ◽  
Neal F. Kassell ◽  
Oren Sagher ◽  
...  
Keyword(s):  
Molecular Weight ◽  
Contractile Response ◽  
Weight Fraction ◽  
Low Molecular Weight ◽  
Equal Concentration ◽  
Content Type ◽  
Basilar Arteries ◽  
Fine Print

✓ The importance of factors within hemolysate in modulating oxyhemoglobin (oxyHb)-induced contraction was examined in an in vitro model of rabbit basilar arteries. When the basilar arteries were exposed to purified oxyHb alone, the contractile response observed was significantly weaker than that seen in arteries exposed to hemolysate containing an equal concentration of oxyHb. In order to delineate the nature of the factors within hemolysate that facilitate contraction, hemolysate was fractionated, and various components were tested individually for their ability to elicit this effect. A low-molecular-weight fraction of hemolysate, ranging from 0.5 to 2.0 kD, elicited only a mild contraction. However, when this fraction was combined with purified oxyHb, the contractile response was comparable in magnitude to that of unfractionated hemolysate. These studies confirm that purified oxyHb is capable of inducing contraction in vitro. The data also demonstrate that oxyHb elicits a significantly weaker contraction than does hemolysate. In addition, the results suggest that low-molecular-weight components in hemolysate (in the 0.5- to 2.0-kD range), while incapable of inducing a potent contraction alone, may act in concert with oxyHb to elicit the vasoconstriction seen following subarachnoid hemorrhage.

scholarly journals Treatment of Experimental Anthrax with Recombinant Capsule Depolymerase

2007 ◽  
Vol 52 (3) ◽  
pp. 1014-1020 ◽  
Author(s):  
Angelo Scorpio ◽  
Steven A. Tobery ◽  
Wilson J. Ribot ◽  
Arthur M. Friedlander
Keyword(s):  
Molecular Weight ◽  
Glutamic Acid ◽  
High Molecular Weight ◽  
Significant Protection ◽  
Bacterial Surface ◽  
Anthrax Infection ◽  
Phagocytic Killing

ABSTRACT Bacillus anthracis produces an antiphagocytic gamma-linked poly-d-glutamic acid capsule that is required for virulence. Capsule depolymerase (CapD) is a membrane-associated poly-γ-glutamate-specific depolymerase encoded on the B. anthracis capsule plasmid, pX02, that is reported to contribute to virulence by anchoring the capsule to the peptidoglycan and partially degrading high-molecular-weight capsule from the bacterial surface. We previously demonstrated that treatment with CapD effectively removes the capsule from anthrax bacilli, rendering them susceptible to phagocytic killing in vitro. Here we report that CapD promoted in vivo phagocytic killing of B. anthracis bacilli by mouse peritoneal neutrophils and that parenteral administration of CapD protected mice in two models of anthrax infection. CapD conferred significant protection compared with controls when coinjected with encapsulated bacilli from fully virulent B. anthracis Ames or the nontoxigenic encapsulated strain ΔAmes and when injected 10 min after infection with encapsulated bacilli from B. anthracis Ames. Protection was also observed when CapD was administered 30 h after infection with B. anthracis ΔAmes spores, while significant protection could not be demonstrated following challenge with B. anthracis Ames spores. These data support the proposed role of capsule in B. anthracis virulence and suggest that strategies to target anthrax bacilli for neutrophil killing may lead to novel postexposure therapies.

scholarly journals Hyaluronan Fragments Improve Wound Healing on In Vitro Cutaneous Model through P2X7 Purinoreceptor Basal Activation: Role of Molecular Weight

PLoS ONE ◽  
2012 ◽  
Vol 7 (11) ◽  
pp. e48351 ◽  
Author(s):  
Kamelia Ghazi ◽  
Uriell Deng-Pichon ◽  
Jean-Michel Warnet ◽  
Patrice Rat
Keyword(s):  
Molecular Weight ◽  
Wound Healing ◽  
Improve Wound Healing
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