Unanswered Questions
217 questions with no upvoted or accepted answers
7
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Does this cycle of reactions appear in nature?
Does anyone know a real-world example of a cycle exactly like this:
or in other words, this:
$$\begin{array}{ccc}
\ce{A + C1 -> C2}\\
\ce{X + C2 -> C3}\\
\ce{C3 -> B + C4}\\
\ce{C4 -> Y +...
- 178
7
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0
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239
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Solve this chemical or biological mystery
I hope this is the best place to pose this unique question. Please forgive me if it's not.
I went into a closet to get a prescription medication that was filled about a year ago.
The label on the ...
6
votes
0
answers
206
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Why is the reverse aldol cleavage of fructose 1,6-bisphosphate highly endergonic under standard conditions?
I have another question similar to this one. I just don't have intuition for why reactions are thermodynamically favorable or unfavorable and I'd like to build it. This time I'd like to ask about ...
CommunityBot
- 1
6
votes
0
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44
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Fatty Acid synthesis - enzymes that vertebrates cannot make
In the fatty acid elongation and desaturation reactions, how are enzymes that insert double bonds after the 9th carbon different from those that insert at the 9th or before? Vertebrates (at least ...
- 69
5
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0
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70
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Do disulfide bonds determine the 3-dimensional structure of a protein or do they just stabilise the 3D structure?
I noticed that most disulfide bonds occur when two cysteine side chains exist in close proximity to each other. Do those cysteine side chains "look out" for each other during folding, that ...
- 41.2k
5
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0
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69
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Why are S-thiocarbamates less toxic than carbamates?
According to Haley and Rhodes, neostigmine bromide (alternatively known as Prostigmine) has an LD50 in mice of around 0.165 mg/kg by IV injection. Pubchem claims that this is also the LD50 for ...
- 1,264
5
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0
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336
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Interaction of trifluoroacetates with acetylcholinesterase
There exists a substance called TMTFA, or 3-(N,N,N-Trimethylammonio)-2,2,2-trifluoroacetophenone. It is known for being able to inhibit acetylcholinesterase at femtomolar concentrations. The TMTFA-...
5
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0
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659
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Why do nitrogen molecules not act as ligands in haemoglobin?
Nitrogen molecules $(\ce{N2})$ have lone pairs, which, as far as I know, is the property of oxygen molecules $(\ce{O2})$ that allows them to act as ligands bonding to iron in haemoglobin in the blood. ...
- 38.4k
5
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0
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1k
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Selective sorption of toxins by polymethylsiloxane polyhydrate
Polymethylsiloxane polyhydrate (PMSPH) is used as enterosorbent for a couple of decades (nowadays under the trademark "Enterosgel"), intended for binding in the gastrointestinal tract and excretion of ...
- 38.4k
5
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0
answers
103
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Phlorizin content in grapes
I work in a winery and we have some problems about a new process involving phlorizin. We know that phlorizin is the major dihydrochalcone found in apples.
I have been reading that this compound is ...
- 6,801
5
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3k
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What methods could be used to preserve scorpion venom?
As extracting scorpion venom goes, how would one most effectively store and preserve the venom for future research?
My thoughts are lyophilization, however I am not sure that would be the best of all ...
5
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0
answers
125
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Catalyzation in Carbonic Acid
I understand the basics of carbonic acid + 1 kcal breaking down into water and carbon dioxide.
However, my professor wants me to draw an energy map showing the catalyst in human blood reducing the ...
- 15.4k
4
votes
0
answers
44
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How are oxidation states of bioinorganic molybdenum/tungsten complexes determined?
Here a screenshot from our lecture on bioinorganic molybdenum complexes, dealing with the catalytic cycle of xanthine oxidase:
It is said that the only biologically relevant oxidation states of Mo ...
- 60k
4
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0
answers
55
views
Are there natural enzymes that catalyze different reactions under different conditions?
Are there natural enzymes that catalyze different reactions under different conditions? For example an enzyme undergoes a conformational change under certain pH and starts catalysing a different ...
- 275
4
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What do we know about the structure of the amylopectin iodine complex?
I am studying a method of finding the ratio between amylose and amylopectin using the difference in color of the amylose-iodine complex(blue) and the amylopectin-iodine complex (red/brown).
Through ...
- 22.5k