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Properties of Dibutyltin Diacetate

 * Molecular Formula :
 * Molar Mass : 351.03 g/mol
 * Melting Point : 7 -10°C (45-50°F)-lit
 * Boiling Point : 142-145°C (288-293°F) at 13 hPa- lit
 * Solubility in Water : insoluble

Dibutyltin Diacetate

Dibutyltin Diacetate

Dibutyl ether

Dibutyltin Diacetate

A Combined Spectroscopic and Theoretical Study of Dibutyltin Diacetate and Dilaurate in Supercritical CO2

Use of Polymethylhydrosiloxane as a Selective, Neutral Reducing Agent for Aldehydes, Ketones, Olefins, and Aromatic Nitro Compounds

Dibutyltin Compounds Effects on PPARγ/RXRα Activity, Adipogenesis, and Inflammation in Mammalians Cells

Critique of Carbonic Anhydrase Mechanism Figure

 * The mechanisms are small, they could be enlarged so that one can perform proper analysis
 * The size of the compounds and arrows of each part of the mechanism can be enlarged as well for better visuals.

Equation:
$$A = A_0 (\frac{1}{2})^\frac{t}{h}$$

$$A$$ = Final amount

$$A_0$$ = Initial amount

1/2 = The split factor

t = time

Article: Iron-Sulfur Cluster Article
In this article, there are a total two edits made on December 5th ,2018 at 00:52 (1st) and 10:49 (2nd). In these edits, Smokefoot has changed the initial format of the introduction.He has edited the work of Ninja Recs. Initially, the article begins similar to the format of an essay , followed by a very brief introduction. The intent of these edits were to eliminate any information or formatting that may go against wikipedia guidelines. The purpose of wikipedia is, an online encyclopedia. It is a platform composed of facts that are presented in from neutral point of view. I believe the edits made were appropriate and necessary because the article is now more presentable and allows for a summary on the topic of iron-sulfur clusters rather than an essay.

[Comments left by Smokefoot after Edit #1]

"Wikipedia is not a school essay. It is a compilation of facts".

[Comments left by Smokefoot after Edit #2]

"("Rem essay beginning with "taking a look at [4Fe-4S] cluster..." including this student critique of biochemical machinery "Despite the [4Fe-4S] clusters having its benefits and flaws,..")"

Why are some statistics shown as negative numbers (-3,296 and -1,805)?
In this article, there are some statistics associated with the edit history , particularly negative numbers. There are two numbers we can observe here that are associated with the Smokefoot edit, there is -3296 and -1805. Both numbers refers to the amount of bytes removed from the article following an edit ( cutting out some information out). The first edit reduced the article by 3,296 bytes and the second edit reduced the article further by -1,805. It is important to understand that if these statistics were positive then the opposite explanation is applied. Positive statistics refer to the addition of information in the form of bytes.

[Merge proposal, withdrawn discussion]
"I propose to merge this article with the one on Iron-sulfur protein. Adding to the confusion, we also have an article on ferredoxin, which I propose to leave alone." --Smokefoot

"I dont think it should be totally merged since organometallic iron sulfur clusters are not biological and should not be mentioned in the iron-sulfur protein article. But the synthetic iron sulfur clusters (like those from Richard Holm at Harvard) should be moved to the iron-sulfur protein article since they are meant to be biomimetic analogs of the biological clusters. Conversely, there should be very little, almost no, discussion of the biological iron sulfur clusters in this article since that is redundant with the iron-sulfur proteins article, so the two sections should be merged and have only one or two sentences with an internal link to the iron-sulfur proteins article. I also dont think this article is very worthwhile since i dont think there are enough non-biological iron sulfur clusters, Im surprised this article was started in the first place"- Kcsunshine999

[Proposal discussion]
"Hello,

I hoping to contribute, my knowledge to this article by discussing the strength, covalency and electron transfer effects." Ninja Recs

"You are writing at a level that indicates that your teacher is needed. Please ask your teacher to read some Wikipedia articles first." --Smokefoot

Article: Carbonic Anhydrase Article
The edits made by Bilal.bhatti96 introduces the carbonic anhydrase by providing the reader an understanding of when the enzyme was discovered (1933) and that it was first discovered in the red blood cells of cows. He also provides details on the relation between the human body and the carbonic anhydrase. The next three edits by Smoke foot remove what Bilal.bhatti96 wrote about the introduction of the carbonic anhydrase. Looking at the introduction presented by Bilal.bhatti96, the information was worthy of notice as it provided the readers with factual information on the history of enzyme and it was presented with a good reference from the PDB (Protein Data Bank).

[Comments left by Smokefoot after Edit #1]

"some redundancy"

[Comments left by Smokefoot after Edit #2]

"mech"

[Comments left by Smokefoot after Edit #3]

"(repeat ref)"

In this article, there are some statistics associated with the edit history , particularly negative numbers. There are three numbers we can observe here that are associated with the Smokefoot edit, there is -642 , -607 and -140. All three numbers refer to the amount of bytes removed from the article following an edit ( cutting out some information out). The first edit reduced the article by 642 bytes the second reduced was by 607, and the last edit was reduced by 140. It is important to understand that if these statistics were positive then the opposite explanation is applied. Positive statistics refer to the addition of information in the form of bytes.

The new paragraph which was added by Bilal.bhatti96 is not a good improvement to the article as it gives information on the definition of an enzyme which is not related to the carbonic anhydrase topic and this information would already be accessible on the enzyme Wikipedia page. The information he provides is already explained with sufficient detail throughout the article. This paragraph added by Bilal.bhatti96 has been removed.

Looking at the “Talk” tab at the top of the Wikipedia “Carbonic anhydrase” article, there has not been enough useful discussion on how this article could be improved. As there hasn’t been enough discussion in the first place which means that this topic has not been analyzed enough. There were some discussions resulting the pictures and the mechanisms provided in the article but there was little discussion on whether the information provided is notable.

Article Rating
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Structure:
Carboxypeptidases can either be classified by the active site mechanism such as metallo-carboxypeptidases or serine carboxypeptidases, or by the preference of substrate such as Carboxypeptidase A or Carboxypeptidase B. All carboxypeptidases carry the presence of zinc at the active site; however, the many different carboxypeptidases have different structures due to the variation in the structure of the active site pocket. Such as, Carboxypeptidase A is a proteolytic enzyme which contains an active site of a hydrophobic pocket which promotes the binding of aromatic side chains.

Mechanism:
Carboxypeptidases hydrolyze peptides at the first amide or polypeptide bond on the C-terminal end of the chain. There is a preference of amino acids with aromatic or branched hydrocarbon chains for the process of hydrolysis. Selective carboxypeptidases are presented as precursors and must be activated from inactive form. Such as the precursor of Carboxypeptidase A is Subunit I of a procarbooxypeptidase complex. Active carboxypeptidase A is provided by enzymatic cleavage which releases about 64 amino acid residues from the N-terminal of subunit I. Zinc is removed by either the presence of chelating agents at neutral pH or at the pH of 5.5 or less to provide inactive apocarboxypeptidase A. Carboxypeptidase A cleaves off single amino acids on the free carboxyl ends of proteins and Carboxypeptidase B cleaves off basic amino acids.

Mechanism:
Carboxypeptidases hydrolyze peptides at the first amide or polypeptide bond on the C-terminal end of the chain. Carboxypeptidases act by replacing the substrate water with a carbonyl (C=O) group. The carboxypeptidase A hydrolysis reaction has two mechanistic hypotheses, via a nucleophilic water and via an anhydride.

In the first mechanistic approach, a promoted-water pathway is favoured as Glu270 deprotonates the nucleophilic water. The Zn2+ ion alongside with positively charged residues, decreases the pKa of the bound water to approximately 7. Glu270 has a dual role in this mechanistic approach as it acts as a general base to allow for the attack of the carbonyl group during nucleophilic addition. It acts as a general acid during elimination when the water proton is transferred to the leaving nitrogen group. The oxygen on the carbonyl group does not coordinate to the Zn2+ until the addition of the water. The deprotonation of the nucleophilic water by Glu270 provides an activated hydroxide which attacks the carbonyl group in the peptide bond in a nucleophilic addition. The negativity charged intermediates are stabilized by the Zn2+ ion during hydrolysis and the interaction between the carbonyl group and the neighbouring arginine, Arg 217. The zinc-bound hydroxid e interacts with the amide with the electrostatic stabilization of the transition state provided by the Zn2+ ion and the neighbouring arginine.

The second mechanistic approach via an anhydride has similar steps but there is a direct attack of Glu270 on the carbonyl group, and then the interaction of Glu270 on the Zn2+-bound amide forms an anhydride instead which can eventually be hydrolyzed by water.