Catalysis
Catalysts work by providing an alternative pathway with a lower activation energy, allowing the reaction to proceed more quickly and efficiently.
This is a fundamental concept in chemistry, with applications in numerous fields, including industrial processes, energy production, and the development of new materials.
Catalytic reactions play a crucial role in the synthesis of pharmaceuticals, the production of fuels and chemicals, and the mitigation of environmental pollutants.
Understading the mechnisms and optimizaiton of catalytic processes is an active area of research, with advances in areas such as heterogeneous catalysis, biocatalysis, and computational modelling driving innovation in this important field.
Most cited protocols related to «Catalysis»
The following cDNAs were amplified by PCR and subcloned into plasmids as follows: residues 546–647 from L. pneumophila SidM (available from GenBank under accession no.
Thereupon, the concept of the profile HMM was adopted to learn computational models from positive sets of phosphorylation sites. To evaluate the learned models, k-fold cross-validation and leave-one-out cross-validation were performed on them. After evaluating the models, the model with highest accuracy in each dataset was chosen.
For each kinase-specific positive set of the phosphorylated sites, the best performed model is selected and used to identify the phosphorylation sites within the input protein sequences by HMMsearch (9 (link)). To search the hits of a model, HMMER returns both a HMMER bit score and an expectation value (E-value). The HMMER bit score is used as the criterion to define a HMM match. We select the HMMER score as the criterion to define a HMM match. A search of a model with the HMMER score greater than the threshold t is defined as a positive prediction, i.e. a HMM recognizes a phosphorylation site. The threshold t of each model is decided by maximizing the accuracy measure during a variety of cross-validations with the HMM bit score value range from 0 to −10. For example, Supplementary Figure S1 depicts the optimization of the threshold of the HMM bit scores in the S_PKA model. The threshold of the S_PKA model is set to −4.5 to maximize the accuracy measure of the model.
When considering a MDD-clustered dataset, for example, MDD-clustered PKA catalytic serine (S_PKA), the HMMs are trained separately from the subgroups of the phosphorylated sites resulted by MDD. Each model is used to search in the given protein sequences for the phosphorylated sites. A positive prediction of a model group is defined by at least one of the models that makes a positive prediction, whereas a negative prediction is defined as all the models that make negative predictions.
It is possible to infer paracrine or autocrine only interactions, or both types (
In order to relate receptors to intracellular signaling, we make use of Reactome and KEGG (39 (link)) interactions downloaded from Pathway Commons. Interactions are assigned to several types that we simplified to facilitate the display of networks afterward. Interaction types ‘interacts-with’ and ‘in-complex-with’ were assigned to the simplified type ‘complex.’ The interaction types ‘chemical-affects,’ ‘consumption-controlled-by,’ ‘controls-expression-of,’ ‘controls-phosphorylation-of,’ ‘controls-production-of,’ ‘controls-state-change-of,’ ‘controls-transport-of’ and ‘controls-transport-of-chemical’ were simplified as ‘control.’ The interaction types ‘catalysis-precedes,’ ‘reacts-with’ and ‘used-to-produce’ were simplified as ‘reaction.’ The simplified type ‘control’ was considered directional whereas ‘complex,’ and ‘reaction’ were considered undirected.
Most recents protocols related to «Catalysis»
Example 5
A solution of Compound C (160 mg, 0.28 mmol) and NEt3 (798 μL, 2.8 mmol) in DCM (2 mL) was treated with phosgene solution (906 μL, 1.4 mmol, 0.5 M in toluene) at 0° C., and the resulting mixture was stirred at 0° C. for 0.5 hr under nitrogen. The reaction mixture was then added to MeOH (2 mL) at 0° C. and stirred for an additional 1 hr. The solvent was removed, and the residue was purified by silica gel chromatography. The THP-protected methylcarbonate was dissolved in MeOH (4 mL), treated with PPTS (catalytic) and stirred at 50° C. for 2 hr. The reaction mixture was concentrated, and the residue was dissolved in MTBE (20 mL) and washed with water and then brine to yield crude THP-deprotected methylcarbonate. The crude product was taken in dioxane (5 mL) along with 10% Pd/C (28 mg) and hydrogenated under a hydrogen atmosphere to yield crude Compound Ia-10 (83 mg) as an oil. MS: m/z 471 [M+Na]+
The following compound was synthesized using similar procedures as above:
Example 4
The catalytic effect of several other reagents having a thiocarbonyl functional group was examined on the leaching of synthetic chalcopyrite, covellite, bornite, and enargite. Experiments were carried out in stirred reactors containing 40 mM ferric sulfate solution at pH 1.8. 1 g of chalcopyrite or covellite was added to the reactors along with an initial concentration of 2 mM of various thiocarbonyl reagents including Tu, TA, SDDC, ETC and TSCA. The Cu extraction curves for chalcopyrite, covellite, bornite, and enargite using all or a subset of the above reagents are shown in
From
Example 39
Generally, pharmacophores for FAAH inhibitors, urea and non-urea based, interact by either carbamoylating or forming transition-state mimics with the catalytic serine residue. However, since a large number of hydrolases utilize a similar catalytic serine residue, many FAAH inhibitors have suffered from poor selectivity. Therefore, the potency of t-TUCB, A-14 and A-21 on several other serine hydrolases was tested. Included in this panel were carboxylesterases, hydrolases involved in xenobiotic detoxification, and paraoxonases and esterases involved in the regulation of arterosclerosis. As is shown in Table 5 below, none of these serine hydrolases were inhibited by t-TUCB, A-14, or A-21.
Example 5
The catalytic effect of leaching solutions prepared with FDS on chalcopyrite, bornite, covellite, and chalcocite leaching was determined in stirred reactor tests. All reactors contained 1.9 L of ferric sulfate solution at pH 1.8 and total iron concentration of 40 mM. 1 g of mineral samples was used in each reactor test. An initial FDS concentration of 1 mM or an initial Tu concentration of 2 mM Tu was used.
The results from stirred reactor tests shown in
Example 3
A solution of Compound C (90 mg, 0.15 mmol), NEt3 (70 μL, 0.5 mmol) and 4-dimethylaminopyridine (DMAP) (1 crystal) in DCM (2 mL) was treated with methoxyacetyl chloride (21 μL, 0.22 mmol) and stirred at RT for 12 hr under nitrogen. The reaction mixture was diluted with MTBE and washed with water and then brine, dried over sodium sulfate and concentrated under vacuum. The residue was purified by silica gel chromatography. The THP-protected methoxyacetate was dissolved in MeOH (4 mL), treated with pyridinium para-toluene-sulfonate (PPTS) (catalytic) and stirred at 50° C. for 2 hr. The reaction mixture was concentrated, and the residue was dissolved in MTBE (20 mL) and washed with water and then brine to yield crude THP-deprotected methoxyacetate. The crude product was taken in dioxane (5 mL) along with 10% Pd/C (18 mg) and hydrogenated under a hydrogen atmosphere to yield crude Compound Ia-8 (64 mg) as an oil. MS: m/z 485 [M+Na]+
The following compounds were synthesized using similar procedures as above:
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More about "Catalysis"
Catalysts work by providing an alternative pathway with a lower activation energy, allowing the reaction to proceed more quickly and efficiently.
This process is crucial in numerous fields, including industrial processes, energy production, and the development of new materials.
Catalytic reactions play a vital role in the synthesis of pharmaceuticals, the production of fuels and chemicals, and the mitigation of environmental pollutants.
Understanding the mechanisms and optimization of catalytic processes is an active area of research, with advances in areas such as heterogeneous catalysis, biocatalysis, and computational modeling driving innovation in this important field.
Key subtopics in catalysis research include reaction kinetics, catalyst design and characterization, reaction optimization, and scale-up.
Commonly used tools and techniques in this field include Prism 6 for data analysis, GC-2014 for gas chromatography, GraphPad Prism 5 for statistical analysis, PyMOL for molecular visualization, Maestro for computational modeling, Xylene for organic synthesis, Protein Preparation Wizard for protein structure preparation, 5-bromo-1-pentyne as a common organic compound, and Lipofectamine 2000 for transfection experiments.
By leveraging these insights and tools, researchers can enhance the reproducibility and accuracy of their catalysis research workflow, leading to the development of more efficient and sustainable catalytic processes.
Whether you're working in the pharmaceutical, energy, or materials science industry, understanding the principles and applications of catalysis is crucial for driving innovation and addressing global challenges.