Questions tagged [chemical-biology]

Questions about the application of chemistry to interrogate and modify biological systems and processes.

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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. ...
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14 views

What are glues for cardboard boxes/crates made of?

Open cardboard boxes/crates, often for foodstuffs, are often glued to hold their shape. What is the glue made? I ask to know if it is biodegradable (for composting/gardening). My preliminary ...
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14 views

Does N-linked glycoslation inhibition increase or decrease par-2 recepto aar activity

Hello guys I need some clarification, i know that melanosome transfer to keratinocytes is regulated in part by par-2, and this receptor is activated by trypsin, sligrl and to a lesser degree tryptase. ...
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1answer
56 views

Can air conditioning cause urine smell?

On rainy days there is a strong urin smell on trains in Tokyo. I suspect this smell comes from ammonia. On Wikipedia I read: Ammonia and ammonium salts are also found in small quantities in ...
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1answer
45 views

How to determine toxicity of a substance? [closed]

I often read description of various compounds or elements as being poisonous. Now I know that through experience we have discovered the toxicity of various substances like lead, chlorine or phosgene ...
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0answers
25 views

Why do foraminifera use less magnesium in their shells when the water is cold?

When scientists study ancient seabed cores, they say they can judge the temperature of the water in the past by analyzing the magnesium to calcium ratio in foraminifera shells (both in the form of ...
3
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1answer
99 views

How are glycosidic linkages formed?

Consider glycosidic linkages in disaccharides. I know a condensation reaction occurs, with the loss of water. But which OH is lost? The O in the linkage belongs to which monosaccharide? Example: ...
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0answers
21 views

Purifying cysteine containing peptides

I would like to purify my peptide having cysteine residue by using HPLC. It is known that thiol containing peptides undergo oxidation and form disulfide linkages. In order to prevent it I used proper ...
4
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1answer
78 views

Why is molybdenum that important in inorganic synthesis as well as biosynthesis of ammonia?

We know that Mo (Molybdenum ) is used as a catalyst for Haber's process, during synthesis of Ammonia from Nitrogen. Again, in biological systems, Nitrogen fixation (ALSO forming Ammonia from Nitrogen)...
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2answers
37 views

What provides the energy allowing membrane proteins to facilitate diffusion across the membrane?

We know that facilitated diffusion requires no energy. But the transport proteins, when bind to a molecule from ECF (extra-cellular face) , the proteins rotate and deliver the molecule into ICF (...
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21 views

Terpene cyclization on terretonin biosynthesis

I would like to ask about a terpenoid cyclization in terretonin biosynthesis in a research paper authored by Matsuda et al., Curr. Opin. Chem. Biol. 31, 2016. It is showed in the paper that The ...
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3answers
65 views

How can I prepare a PBS (Phosphate Buffer Solution)? pH=7.4 [closed]

Phosphate-buffered saline (abbreviated PBS) is a buffer solution commonly used in biological research. It is a water-based salt solution containing disodium hydrogen phosphate, sodium chloride and, in ...
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29 views

How to recreate bioluminescence in fireflies in a lab?

I have several mg/mL of D-luciferin, luciferase (firefly), ATP solution (25 mmol) and MgSO4 (for the mg2+ ions). The experiment has to be done in cuvettes of 2,5 mL (if I get any results, it will be ...
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2answers
165 views

How does existence of alpha and beta form of glucose prove that it exists as a cyclic structure

My book says that Glucose is found to exist in two different crystalline forms which are named as $\alpha$ and $\beta$. Next it says that This behaviour could not be explained by the open ...
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60 views

Oil + UV radiation = cholecalciferol?

According to a web site about health (Antranik): The oil that naturally comes from our skin is a type of cholesterol. Whenever we stand under direct sunlight, the ultraviolet rays react with ...
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1answer
571 views

Is there any difference between isotonic and isosmotic solution?

Is there any difference between isotonic and isosmotic solution? Can we say isotonic solution do not show osmosis because they have same osmotic pressure?
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1answer
48 views

What would happen if we had a different kind of metal in our bloodstream? [closed]

It is a common fact that we have iron in our blood. But what if we had something different in its place? Like instead of iron what if it was copper, or silver, or what if we had gold in our blood ...
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1answer
44 views

Opening the imidazoline ring in tolazoline

Hello. I was studying about the alkaline ring opening or purines. While doing research, i came across this compound. This got me thinking if we can use the same procedure to open the imidazoline ring ...
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4answers
65 views

A liquid that forms a surface membrane that prevents evaporation but allows oxygen to pass through

I'm a biologist. I have a water solution with living cells in a tiny well (10 um). I need to keep the solution from evaporating for several days in a warm incubator. I'm looking for a liquid to place ...
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0answers
30 views

How many natural products are there in existence? [closed]

Hi I'm doing a project on natural products and I'm wondering if somewhere there is at least an estimated number of how many exist? If this exists somewhere can you please provide a reference. ...
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77 views

When the present state of knowledge concerning central noradrenergic transmission was established?

Some time ago I began to search for descriptions of the mechanisms responsible for the regulation of noradrenergic transmission in the central nervous system of man and to my great surprise the most ...
3
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1answer
183 views

Solving two electron integral numerically

Is there any software package in python or C to evaluate two electron integral repulsion integral in quantum chemistry of atoms. I am trying to solve the helium atom by constructing many body basis....
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1answer
59 views

C-4 oxidation of octanoic acid to 4-oxooctanoic acid

I am leading a project in which I am attempting to synthesize 4-oxooctanoic acid in a (mostly) biological pathway. Currently, I have reached a dead-end. I have a way to create octanoic acid through ...
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1answer
21 views

Enzyme Kinetics two enzymes in complex with one substrate

Given an enzyme reaction where two enzymes are required to form the complex, for example $\ce{2E +S-> E3S->2E +P}$, how would I calculate complex concentration assuming steady state ...
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1answer
140 views

Why does the structure of haemoglobin change when the ferrous ion changes to ferric ion?

It is said that $\ce{Fe^2+}$ can bind oxygen while $\ce{Fe^3+}$ cannot. Why is that so? $\ce{Fe^3+}$ has an extra electron, it could bind more easily to the oxygen. And how and why does the structure ...
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Question about the composition of a 1902 non-polarisable electrode diagram by Jagadis Bose

In his work, "Response in The Living and Non-living" (1902); page 6, Jagadis Bose describes a method for detecting nerve response. He explains that he uses iso-electric contacts with no current in the ...
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2answers
2k views

Is Biotin water-soluble or fat soluble?

Vitamin $\ce{B_7}$ or Biotin is a member of the vitamin B complex. Members of the vitamin B complex are usually known to be water soluble. However, this webpage mentions that biotin is water soluble. ...
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1answer
97 views

Modification to improve antibacterial activity

I have difficulties with part b). For C, it's clear to make a bulky dimethoxybenzene group in order to block the C=O group from reacting with b-lactamase. However, in A, how does the structure of ...
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0answers
54 views

Why do you not need sun protection whe the UV index is 3?

In Australia, they recommend sun protection when the UV index is above 3. Why is this? Surely whenever it's above 0 there are still UV rays hitting your skin? Would 10 minutes in the sun with a UV ...
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1answer
81 views

Is there any obvious relation between sodium bicarbonate and ammonia; (how) can sodium bicarbonate be involved in producing ammonia?

Using sodium bicarbonate as a deodorant sometimes can produce a strong ammonia smell. Is there some obvious chemical explanation for this?
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127 views

Does melanostatin peptide whiten the skin in a similar manner as to how melanotan darkens it?

I was reading about peptides and came across an interesting peptide that bodybuilders use to darken their skin. How can peptides change the genetic makeup of someone's skin and darken it? I also ...
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1answer
2k views

Reduction of methylene blue

Why does methylene blue (which is initially blue) reduce to form a colorless solution? I was told by my teacher that it has to do with the presence of an additional double bond on methylene blue, ...
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2answers
68 views

Separation of solvent from residue of material. [closed]

I have a residue of 2kl in which 1.8kl is solvent (EDC) and rest material is residue. First i was thinking to go with normal distillation to recover our solvent. But i heared somewhere that there is ...
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4answers
8k views

How are poisons discovered? Does someone have to die/be poisoned from it first?

How are poisons discovered? Does someone have to die/be poisoned from it first? Or are there other ways of discovering the harmfulness of a substance? Perhaps everything is tested on other animals ...
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2answers
1k views

Does calcium hydroxide react with citric acid in orange juice?

I noticed that calcium-fortified orange juice on the shelf at my local grocery store contains calcium in the form of calcium hydroxide. And I also noticed a couple other ingredients that ordinary ...
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0answers
37 views

Cytotoxicity of Ru-complexes

I have a basic question: why are Ru(II)-complexes cytotoxic? What I know is that depending on the used ligand some of them interact with the DNA either via DNA-pi-stacking (intercalation) or binding ...
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61 views

Lowest Michaelis constant Km

I want to find a lower limit of the Michaelis constant for some evaluations of Michaelis-Menten enzyme kinetics. What is the lowest $K_m$ you ever encountered? Is there a theoretical limit?
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1answer
83 views

Is it true that organic chemistry as an independent research field is no longer developing? [closed]

One of my professors told me that organic chemistry has become a tool for biological research, rather than an active research field of its own. Is this assertion valid? Does it describe correctly the ...
4
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1answer
145 views

Why does orthocresol behave as a skin irritant?

o-Cresol or ortho-Cresol or 2-methylphenol is a constituent of tobacco smoke, and, like most other phenols, behaves as a skin irritant, causing a burning sensation when it comes in direct contact, or ...
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0answers
317 views

Why does hydrochloric acid not damage the human stomach? [closed]

Hydrochloric acid ($\ce{HCl}$) is found in the stomach, so why it doesn't damage the stomach despite that it is considered to be one of the most dangerous acids?
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0answers
64 views

Pulling Calcium Phosphate from Animal Bones

I am looking to pull Calcium Phosphate out of animal bones (chicken, fish, etc) without destroying the collagen. If I soak animal bones in brown rice vinegar will the vinegar pull out Calcium ...
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0answers
62 views

Do any efforts to construct artificial biochemistries exist and what compounds are they based on? [closed]

I'm a researcher interested in the fields of origins of Life, astrobiology and theoretical biology in general but I must admit I think my knowledge of chemistry outside biochemistry is a little bit ...
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1answer
330 views

Why in solution glucose not convert into galactose or mannose? [closed]

In glucose solution glucose is present in ring form but 1% can be in open chain form. As carbon carbon bond (c-c) roation is possible. Then why does Glucose can't be converted in galactose or mannose ...
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1answer
4k views

Can reaction of gastric acid with swallowed things be dangerously exothermic?

Okay, okay. I know that swallowing a large enough amount of any substance would be considered dangerous. That isn't the point of this question, however. As you probably know, the stomach has ...
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1answer
827 views

Taste same but why not LiCl a substitute for NaCl (common salt)?

A clinical paper from 1949 [1] observes the toxicity of LiCl, at very low concentrations. That just went over my head... Is toxicity the only reason to avoid LiCl as a substitute for NaCl (specially ...
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0answers
753 views

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 ...
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2answers
1k views

Etymology of “click chemistry”

According to Wikipedia, the term click chemistry was coined by K. Barry Sharpless in 1998. What does the word 'click' mean here? I guess it means "join" here but I'm not sure.
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1answer
4k views

What does the Pi stand for in the reaction for biological nitrogen fixation?

In the reaction for biological nitrogen fixation, what does the Pi stand for in the products? $$\ce{N2 + 8H + 8e- + 16 ATP -> 2NH3 + H2 + 16ADP + 16 P_{i}}$$
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144 views

What is the most likely reaction between minocycline and tramadol in physiological conditions?

Minocyline (left) and Tramadol (right) are two commonly prescribed medications containing typical organic functional groups. What would an expert chemist surmise as the first or most-likely reaction ...
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1answer
195 views

How to measure a distance along the surface of a protein in a PDB

I would like to measure the distance between two active sites in a protein complex (pdb), but I do not find a straightforward way to do it. To be more precise I need the distance along the surface ...