The scientific study of chemical processes in living organisms, including, but not limited to, living matter.

learn more… | top users | synonyms

0
votes
1answer
31 views

Really understanding oncotic pressure and osmosis

I can't wrap my head around the idea of oncotic pressure and osmolarity, logically. I imagine a blood vessel. It is FILLED with proteins...Like a ton of proteins and solutes. So this means, according ...
1
vote
0answers
5 views

Parameter effects on kinetics of esterification for bio-diesel production

I want to discuss the effect of parameters on the kinetics of esterification for bio-diesel production. In esterification process, temperature effect and molar ration are two important parameters. ...
0
votes
1answer
32 views

Superoxide dismutase of Mn (SOD)

I have a little problem with my paper about Mn superoxide dismutase. On this picture we have "B" behind the 3 OH ions, I really don't understand what is this. Where is this "B" from? Please, help me, ...
0
votes
0answers
10 views

Mechanism of thyroid hormone synthesis: iodation and free radical formation

In the synthesis of thyroid hormone, what part of the thyroid peroxidase hormone is specifically responsible for abstracting the free radicals from the aromatic side chains in the iodated tyrosine ...
0
votes
1answer
20 views

Are β-sheets formed from one or more polypeptides?

I know that a β-strand forms bonds with another β-strands and so on and thus a β-sheet is formed, but are those strands from the same polypeptide? And does their distance matter? Do they have to be ...
0
votes
1answer
16 views

Chondroitin Sulfate (greater volume in solution than in crystal form)

I've read in a textbook on biophysics that chondroitin sulfate occupies a greater volume in a solution than in crystalline form. Why is that? Is it because of hydrogen bonds in solution that the ...
0
votes
0answers
16 views

Loooking for dataset of proteotypic and non-proteotypic peptide

I doing experimentation for peptide prediction using machine learning. I need some data for testing. I already have one dataset, but I need another one or two for verification. I'm looking for one a ...
1
vote
1answer
30 views

How was cholestyramine discovered?

How were the properties of bile acid sequestrants like cholestyramine discovered? The earliest reference to the chemical I could find was the following article which does not discuss the history of ...
2
votes
1answer
31 views

Dipole and size of a thioether relative to hydrocarbon

I am an enzymologist and I would like to check whether the consensus of how enzymes tell thioethers from hydrocarbons on substrates is a fact or fiction. So are any of these wrong? S–π ...
3
votes
2answers
96 views

Separating Lipids from Milk

I am trying to develop a procedure to test the percent mass of lipids in (update: homogenized) milk. It doesn't need to be very accurate, just an interesting application of chemical principles. As I ...
0
votes
0answers
13 views

How to tell when DNA will be positively or negatively supercoiled?

Is there any indication of when DNA will be + or - supercoiled based on the number of base pairs or number of pairs per turn or any other metric?
1
vote
0answers
12 views

Glycogen Hydrolase

Can glycogen hydrolase cleave both glycogen and starch bonds? My intuition says yes because they are both a 1-4(6) glycosidic linkages but I bet I am missing something.
1
vote
0answers
14 views

Effect of a double mutation on the stability of a folded protein?

the question is shown as follows: My reasoning is that the mutation leads to stabilisation of the protein as Tyr121 is a better H-donor than Ser53 therefore stronger H-bonds formed. Also there seems ...
2
votes
1answer
39 views

Deriving kinetic equations for a complex reaction system

I have a system of protein reactions that I've derived differential equations for the kinetics of. I'm using them to run simulations to fit the rate parameters, but the simulations at present are ...
1
vote
0answers
32 views

What is the structural difference between ketogenic amino acids and glucogenic amino acids?

We know some amino acids could go in ketogenosis path way ,some in glucogenic and some in both ..i 'm wondering to know what the differences are between the amino acids the make this situation.
1
vote
1answer
28 views

Enzyme Specificity vs Selectivity

Background: I can see a difference in stereoselective and stereospecific reactions in organic chemistry. However, both terms are used interchangeably as synonyms in a biochemistry class. Question: ...
12
votes
1answer
919 views

Why/how is blood red? (colours of hemoglobin)

Oxyhaemoglobin is red, deoxyhaemoglobin is bluish-purple, and carboxyhaemoglobin is a cherry red colour. Evidently in the porphyrin around the iron molecule in heme there is a conjugated pi system ...
0
votes
1answer
13 views

Does mechanotransduction of cells play a role in the biocompatibility of titanium?

What exactly is mechanotransduction? The definition seems to vary from source to source. Some indicate that mechanotransduction is the underlying principle where cells pull on the surface they grow on ...
2
votes
0answers
23 views

Microarray SPR imaging vs “regular” SPR?

Background: I am taking a biochemistry course, and we have had some basic introduction to surface plasmon resonance (SPR). I don't have a very strong background in biophysical chemistry. Task: I am ...
0
votes
0answers
9 views

Thiosulfate from N-acetylcysteine

Can you derive thiisulfate (S2O3 (-2)) from n-acetylcysteine (C5H9NO3S) in a biological system such as the airways? If so, how?
3
votes
1answer
47 views

l- versus d-glucose

I recently purchased Dextrose from a local bulkfood store. I want to use it instead of table sugar. My concern is that it may be l-glucose instead of d-glucose. According to Wikipedia l-glucose is too ...
4
votes
3answers
96 views

Why is the Mg2+ ion preferred over other ions in chlorophyll?

Chlorophyll has a $\ce{Mg^2+}$ ion. Why is it preferred over other ions? I mean, what happens if there is $\ce{Zn^2+}$ or $\ce{Ca^2+}$ or any other cation instead of $\ce{Mg^2+}$?
0
votes
0answers
16 views

Differences between anionic and cationic surfactant in DNA extraction?

What's the main difference in DNA extraction between using an anionic surfactant (like SDS) or a cationic surfactant (like CTAB)?
0
votes
0answers
12 views

Can (2,4-dinitrophenyl)hydrazine be used in osazone test?

For osazone test we use phenylhydrazine but what difference it would make if we replace it by its derivative (2,4-dinitrophenyl)hydrazine and will there be any change in crystal structure of the ...
13
votes
2answers
191 views

Why does fluorine act as a leaving group in organophosphates?

C-F bond is the strongest single bond in organic chemistry with a bond energy of $\ce{453 kJ\,mol^{-1}}$. And it is very difficult to break this bond and F does not act as a leaving group. However, ...
3
votes
0answers
17 views

Measuring reaction rates when reactants and products both have (different) molar extinctions at the chosen wavelenghth

In my Biochem labs we would always measure the consumption of NADH, and they always noted that it was useful that NAD+ had essentially no absorbance at 340 nm, which allowed us to directly relate ...
0
votes
1answer
24 views

Why is the effect of competitive antagonist less than the effect of non-competetive antagonists?

Drugs can be provided as a competive or non-competitive form of agonists. But the effect of non-competitive antagonists is much more than the other, so what is the cause of that? And are there some ...
1
vote
0answers
23 views

Molecular mechanism describing the action of serotonin [closed]

I am doing an assignment of serotonin and i was wondering if you could explain how serotonin's molecular structure gives it its favorable properties. I have done so much research on the molecular but ...
1
vote
0answers
21 views

Molecular mechanism behind the action of neurotransmitter Citalopram [closed]

What parts of the neurotransmitter Citalopram (which blocks the reuptake channels of Serotonin) on a molecular level enable it to do its job. the chemistry behind it for a grade 12 chemistry ...
0
votes
0answers
14 views

Proteolytic enzyme assay using casein as the substrate

To determine the proteolitic activity of an enzyme, the enzyme assay can be used using the casein as the substrate. In the laboratory can I use a fresh milk sample instead of casein?
1
vote
1answer
26 views

What is the chemistry behind heat produced when blood is bleached?

When I discard blood (20-40 mL) in a beaker containing bleach (400mL), I can feel that heat is produced in the beaker. What is the chemistry behind it? Will heat be produced due to Lysis of haem ...
2
votes
1answer
60 views

Why can't electrons be transferred using hydrogen ions?

I have a homework question that asks: Recognizing how oxidation and reduction occurs is essential for analyzing and understanding biochemical reactions. Which of the following methods would NOT ...
0
votes
0answers
23 views

How to calculate molar concentration of phenol red when mixed with water and a buffer?

The concentration of phenol red is 1E-4 M. The initial volume used was .1 mL and is then mixed with .9 mL of water and 4.0 mL of a .1M borate buffer of pH 9.8. I used a simple M1V1 = M2V2. Where M1 = ...
1
vote
0answers
19 views

Lookup for transporter locations in human organisms [closed]

I am scared that this question is a bit naive and probably even wrongly placed here... However, I'll give it a try and hope for the best :) I am interested in several transporters and cotransporters ...
1
vote
1answer
28 views

Difference between biosynthesis in organism versus lab

Are there different terms for biosynthesis of a compound naturally in an organism versus the biosynthesis using chemicals in the laboratory or is it just "biosynthesis"?
7
votes
1answer
125 views

Relation between Gibbs energy and net reaction rate

I have come across some papers in biochemistry that seem to claim that a reaction can be "near equilibrium" even though the flux through the reaction (net reaction rate) is large. For example, this ...
3
votes
1answer
161 views

Find the number of water molecules “embedded” in sucrose

Recently I got a question as follows: How many molecules of water are joined with 12 atoms of carbon in a molecule of sucrose ? (A) 12 (B) 11 (C) 6 (D) 10 I am unable to ...
0
votes
1answer
31 views

What is a prosthetic group of protein? What are prosthetic groups?

I have found this term while I studying the topic of ETS in respiration in plants.
3
votes
0answers
47 views

Comparing pKa of Alpha and Beta Amino Acids

The $\mathrm{p}K_{\mathrm{a}}$ of the functional groups in L-glutamic acid (shown above on the right) from left to right are $4.1, 9.5$ and $2.1$. Predict the $\mathrm{p}K_{\mathrm{a}}$ values of ...
1
vote
1answer
44 views

Is it practical to extract zymase from yeast for ethanol production?

Suppose I wanted to make some ethanol fuel. Normally, I would get yeast, mix with water, add sugar and wait. However, there is an enzyme (zymase) in yeast that does this. Looking at the Wikipedia ...
2
votes
0answers
26 views

What are some technologies/biosensors for real time kinetic analysis of reactions? [closed]

I am in a lab that has used surface plasmon resonance (SPR) and ELISA very heavily over the past few years, and we are thinking of getting a new machine. I'm wondering what other technologies exist ...
0
votes
0answers
28 views

How is adenosine synthesized in biology?

I understand the constituent parts of adenosine, ribose and adenine. I also know adenosine can be broken down from ATP anabolically. However, I am interested to know whether there is also a catabolic ...
0
votes
0answers
26 views

Biosynthesis of Xanthoxylin

Anyone can find a source for or explain the biosynthetic pathway for Xanthoxylin? It's the last practice problem I have for an exam, and I just can't seem to find info on it. Thanks!
3
votes
0answers
29 views

Mechanism: explanation of final step in synthesis of the thyroid hormones (T4, T3)

In the following mechanism for the synthesis of T3 (triiodothyronine) on thyroglobulin, what are the factors causing the last step to occur? Does it have something to do with the electron density of ...
3
votes
1answer
85 views

What is the empirical formula of Haemoglobin?

Everywhere I look on the internet tells me a different formula. Are there genuinely different formulas for Haemoglobin, or are some of my internet sources incorrect? (I know there are different ...
1
vote
1answer
34 views

Which coloring agents are responsible for the color in red tea and yellow tea?

Have this question in a biochemistry course, can't seem to find it anywhere. Anyone happen to know an alkaloid or something else involved? Thanks a lot!
0
votes
1answer
61 views

Why is vitamin C called an antioxidant?

According to Wikipedia, vitamin C (ascorbic acid) "may also act as an antioxidant against oxidative stress," and is "widely used as a food additive, to prevent oxidation." But acids are, by ...
1
vote
0answers
23 views

Water and Bonds [closed]

I am doing a study packet and it asks Water contains what bonds. I said covalent bonds. Then it says The electron bully is___. It is therefore ___charged. The other element,____, is the electron loser ...
1
vote
1answer
55 views

Question about DNP derivatives of amino acids (specifically epsilon-DNP-lysine)

I have a pretty basic biochemistry question but am having trouble finding the answer to it: Normally, DNFB (dinitrofluorobenzene, or 1-fluoro-2,4-dinitrobenzene to be exact) reacts with just the ...
1
vote
0answers
31 views

How do I analyse this data? (optimization experiment)

I conducted an experiment to find the optimal concentration for sugar in yeast respiration, and this is the data I found: What do I do from here? Do I just fit a linear model on the increasing ...