All Questions
Tagged with biochemistry stereochemistry
20
questions
6
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2
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46k
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How do we assign alpha/beta status in polysaccharides?
In polysachharides like sucrose or any other disachhaharides, how is it that we assign whether the glycosidic bond is alpha/beta ?
For example the images here: http://forums.studentdoctor.net/...
CommunityBot
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3
votes
1
answer
129
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What do we get when we joint two α- glucoses via an α1,4 bond?
What do we get when we joint two α- glucoses via an α1,4 bond?
Is it alpha maltose or beta maltose?
In other words, if we cleave amylopectin with amylase (α-amylase or β-amylase), which form of ...
CommunityBot
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-2
votes
1
answer
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Are the anomeric hydroxy groups of α-maltose and β-maltose, axial or equatorial, respectively?
This Q&A is a continuation from the following Q&A;
What do we get when we joint two α- glucoses via an α1,4 bond?
More straightforwardly, the question may focus on whether the bond represented ...
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1
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1
answer
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How are non-racemic drugs produced?
In many cases the L- or S- stereoisomer of organic compounds is vastly more bioactive than other enantiomers. So we see pharmaceutical companies producing escitalopram (i.e., S-citalopram), ...
- 3,340
1
vote
0
answers
121
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Why are glyosidic linkage of glucose and fructose rings often occurring at the 1' and 4' prime positions?
Here are some example combinations from my textbook:
In all of these combined products, the reactive centres seem to be the carbon at first position/ fourth position from the oxygen in priority. Is ...
- 802
7
votes
4
answers
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Ramachandran plot Phi(ϕ) Psi(ψ) dihedral angle Convention for Zero, Positive and Negative value- old and new
Update: possible duplicate: What is the precise definition of Ramachandran angles?. Question modified.
G.N. Ramachandran et al, in their own work (PMC) (DOI), did not used phi(ϕ) and psi(ψ) as we use ...
6
votes
1
answer
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Does the mechanism of AChE inhibition by Isoparathion depend on chirality?
It is known that the inhibition of acetylcholinesterase by isomalathion can proceed either with diethyl succinate as the leaving group or thiomethyl, depending on the specific stereoisomer of ...
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1
vote
1
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Does anyone know what program was used to make this molecular structure picture? [closed]
I am a quantum chemistry beginer, and this picture color scheme is classic. I wonder how to make such pictures by myself.
- 5,685
1
vote
1
answer
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Correct way of drawing D-configuration with this stereochemistry?
Hello! I have completely memorized how to draw all 20 amino acids in the way seen in the picture (middle, between the "ball-and-stick" and fisher projection)
By my understanding this is in the L ...
2
votes
0
answers
85
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Differences in efficacy of oxime reactivators in organophosphate poisoning
Compounds containing an oxime functional group, such as 2-PAM and obidoxime, are used in the treatment of poisoning with organophosphorus compounds. These oximes reactivate the enzyme ...
- 1,264
2
votes
2
answers
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Why do chiral biological molecules only exist as one enantiomer? Does it have any advantage?
Why is it that chiral biological molecules are enantiomerically pure? The other enantiomer would have the same reactivity, and the only difference is their angle of rotation of plane polarized light. ...
- 41.2k
2
votes
2
answers
172
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Are the stereoisomers of nucleosides actually anomers?
An anomer is an epimer at an (hemi)-acetal carbon like $\ce{R2C(OR')2}$.
Why is the 1'-position of a nucleoside referred to as the anomeric center despite the lack of acetal functional groups?
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21
votes
3
answers
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What are known examples of drugs that racemize/stereoconvert in vivo, and how are they converted?
It is known that although only the (S)-enantiomer of the infamous sedative thalidomide possesses teratogenic properties, it is not very useful to administer the pure (R)-enantiomer since it is ...
- 5,164
5
votes
2
answers
711
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Isn't 11-trans-retinal more stable than 11-cis-retinal?
11-cis-retinal can be found as a part of rhodopsin and it is the non-excited form of retinal. By absorbing light, retinal goes to a higher energy state and converts to 11-trans-retinal. At least I ...
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9
votes
1
answer
576
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How can a Hydrogen make such a difference?
Looking at familiar bodily fluids for a learning session. At first glance they both look the same. Then I noticed the N=C in biliverdin and HN-C in bilirubin. How can a N=C (imine group) and HN-C (...
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