Kinetics of formation of unitary three-dimensional structural elements: numerical experiment

The tissue inhibitors of metalloproteinases (TIMPs) are endogenous inhibitors of the matrix metalloproteinases (MMPs), enzymes that play central roles in the degradation of extracellular matrix components. The balance between MMPs and TIMPs is important in the maintenance of tissues, and its disruption affects tissue homoeostasis. Four related TIMPs (TIMP-1 to TIMP-4) can each form a complex with MMPs in a 1:1 stoichiometry with high affinity, but their inhibitory activities towards different MMPs are not particularly selective. The three-dimensional structures of TIMP-MMP complexes reveal that TIMPs have an extended ridge structure that slots into the active site of MMPs. Mutation of three separate residues in the ridge, at positions 2, 4 and 68 in the amino acid sequence of the N-terminal inhibitory domain of TIMP-1 (N-TIMP-1), separately and in combination has produced N-TIMP-1 variants with higher binding affinity and specificity for individual MMPs. TIMP-3 is unique in that it inhibits not only MMPs, but also several ADAM (a disintegrin and metalloproteinase) and ADAMTS (ADAM with thrombospondin motifs) metalloproteinases. Inhibition of the latter groups of metalloproteinases, as exemplified with ADAMTS-4 (aggrecanase 1), requires additional structural elements in TIMP-3 that have not yet been identified. Knowledge of the structural basis of the inhibitory action of TIMPs will facilitate the design of selective TIMP variants for investigating the biological roles of specific MMPs and for developing therapeutic interventions for MMP-associated diseases.

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Kinetics of cyclization of S-ethoxycarbonylmethylisothiouronium chloride to 2-imino-4-thiazolidone

Collection of Czechoslovak Chemical Communications ◽

10.1135/cccc19790912 ◽

1979 ◽

Vol 44 (3) ◽

pp. 912-917 ◽

Cited By ~ 1

Author(s):

Vladimír Macháček ◽

Said A. El-bahai ◽

Vojeslav Štěrba

Keyword(s):

Hydrochloric Acid ◽

Dilute Hydrochloric Acid ◽

Base Catalysis ◽

General Base ◽

Rate Limiting Step ◽

Limiting Step ◽

Kinetics Of Formation ◽

Acid Catalyzed ◽

Rate Limiting ◽

Kinetics Of

Kinetics of formation of 2-imino-4-thiazolidone from S-ethoxycarbonylmethylisothiouronium chloride has been studied in aqueous buffers and dilute hydrochloric acid. The reaction is subject to general base catalysis, the β value being 0.65. Its rate limiting step consists in acid-catalyzed splitting off of ethoxide ion from dipolar tetrahedral intermediate. At pH < 2 formation of this intermediate becomes rate-limiting; rate constant of its formation is 2 . 104 s-1.

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Cyclization and acid-catalyzed hydrolysis of O-benzoylbenzamidoximes

Collection of Czechoslovak Chemical Communications ◽

10.1135/cccc19862786 ◽

1986 ◽

Vol 51 (12) ◽

pp. 2786-2797

Author(s):

František Grambal ◽

Jan Lasovský

Keyword(s):

Reaction Rate ◽

Kinetic Isotope ◽

Acid Base Equilibrium ◽

Mineral Acids ◽

Kinetics Of Formation ◽

Acid Catalyzed ◽

Ph Scale ◽

Kinetics Of ◽

Hydrolysis Of ◽

Derivatives Of

Kinetics of formation of 1,2,4-oxadiazoles from 24 substitution derivatives of O-benzoylbenzamidoxime have been studied in sulphuric acid and aqueous ethanol media. It has been found that this medium requires introduction of the Hammett H0 function instead of the pH scale beginning as low as from 0.1% solutions of mineral acids. Effects of the acid concentration, ionic strength, and temperature on the reaction rate and on the kinetic isotope effect have been followed. From these dependences and from polar effects of substituents it was concluded that along with the cyclization to 1,2,4-oxadiazoles there proceeds hydrolysis to benzamidoxime and benzoic acid. The reaction is thermodynamically controlled by the acid-base equilibrium of the O-benzylated benzamidoximes.

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A Novel Pseudomonas geniculata AGE Family Epimerase/Isomerase and Its Application in d-Mannose Synthesis

Foods ◽

10.3390/foods9121809 ◽

2020 ◽

Vol 9 (12) ◽

pp. 1809

Author(s):

Zhanzhi Liu ◽

Ying Li ◽

Jing Wu ◽

Sheng Chen

Keyword(s):

3D Structure ◽

Three Dimensional ◽

Optimal Temperature ◽

Reaction Conditions ◽

Enzymatic Production ◽

Physiological Properties ◽

Potential Applications ◽

Kinetics Of ◽

Optimal Reaction ◽

Gene Age

d-mannose has exhibited excellent physiological properties in the food, pharmaceutical, and feed industries. Therefore, emerging attention has been applied to enzymatic production of d-mannose due to its advantage over chemical synthesis. The gene age of N-acetyl-d-glucosamine 2-epimerase family epimerase/isomerase (AGEase) derived from Pseudomonas geniculata was amplified, and the recombinant P. geniculata AGEase was characterized. The optimal temperature and pH of P. geniculata AGEase were 60 °C and 7.5, respectively. The Km, kcat, and kcat/Km of P. geniculata AGEase for d-mannose were 49.2 ± 8.5 mM, 476.3 ± 4.0 s−1, and 9.7 ± 0.5 s−1·mM−1, respectively. The recombinant P. geniculata AGEase was classified into the YihS enzyme subfamily in the AGE enzyme family by analyzing its substrate specificity and active center of the three-dimensional (3D) structure. Further studies on the kinetics of different substrates showed that the P. geniculata AGEase belongs to the d-mannose isomerase of the YihS enzyme. The P. geniculata AGEase catalyzed the synthesis of d-mannose with d-fructose as a substrate, and the conversion rate was as high as 39.3% with the d-mannose yield of 78.6 g·L−1 under optimal reaction conditions of 200 g·L−1d-fructose and 2.5 U·mL−1P. geniculata AGEase. This novel P. geniculata AGEase has potential applications in the industrial production of d-mannose.

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Effect of CTABr (surfactant) on the kinetics of formation of silver nanoparticles by Amla extract

Journal of Molecular Liquids ◽

10.1016/j.molliq.2021.115537 ◽

2021 ◽

Vol 329 ◽

pp. 115537

Author(s):

Nazia Iqbal ◽

S.M. Shakeel Iqubal ◽

Aejaz Abdullatif Khan ◽

Tasneem Mohammed ◽

Ali Mohamed Alshabi ◽

...

Keyword(s):

Silver Nanoparticles ◽

Kinetics Of Formation ◽

Kinetics Of

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A test of airborne, side-looking synthetic-aperture radar in central Newfoundland for geological reconnaissance

Canadian Journal of Earth Sciences ◽

10.1139/e91-025 ◽

1991 ◽

Vol 28 (2) ◽

pp. 257-265 ◽

Cited By ~ 14

Author(s):

D. F. Graham ◽

D. R. Grant

Keyword(s):

Surface Roughness ◽

Synthetic Aperture Radar ◽

Three Dimensional ◽

Synthetic Aperture ◽

Structural Elements ◽

Terrain Classification ◽

Regional Trends ◽

Valuable Complement ◽

Wide Swath ◽

Aperture Radar

Side-looking, C-band synthetic-aperture radar (SAR) penetrates cloud and fog, and operates day or night, to produce pseudo-three-dimensional terrain images with enhanced topography and surface roughness. The images, which have a 20 m resolution and cover large areas, have been used to map the regional trends, patterns of lineaments, and terrain types over a 6200 km2 area of complex lithology, structure, and drift cover. Four lineament classes are differentiated. Glacial trends are clear, and bedrock structures (faults, fractures, joints, foliation, and folded bedding) with relief expression at the surface show through the drift as lineaments. They accurately reproduce most known features when compared with bedrock and Quatenary geology maps. Hitherto unrecognized structural elements are revealed. Tones and textures reflect minute surface roughness variations useful in terrain classification. SAR wide-swath-mode imagery is thus a valuable complement to aerial photography, and is superior in revealing hummocky moraine, ribbed moraine, boulder fields and stony till. Wider use of this imagery is encouraged.

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