New answers tagged biochemistry
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As a matter, of fact, yes, uncharged phosphoryl thiocholines do seem to interact with acetylcholinesterase differently compared to their charged analogs. For example, it has been reported that
Sundwall (1961) reported that P2S was considerably more effective as
an antagonist of the lethal action of 37 SN
+(isopropoxy-2-trimethylammonio-tiomethylphosphino ...
3
Based on a quite old reference 1 (which I'm using because it's available free by open access), peptide bond formation at 25 C is unfavorable only because of a large enthalpy change, on the order of 1.5 kcal/mol (6.3 kJ/mol). The entropy change is actually favorable, with $T\Delta S$ being about 1 kcal/mol (4kJ/mol), so the net free energy change is ~ + 500 ...
21
Thousands of different chemicals, previously spatial separated, are mixed together after thermal death of cells, and kept at high temperature to react well. Final taste will depend on original system, but will develop by way unpredictable theoretically from basic principles.
The answer for a particular biological source requires detailed knowledge about ...
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Your reference electrode contains chlorine and silver, the ions from these elements can kill bacteria, you should avoid liberating gases too: oxygen is killing anaerobic bacteria. To avoid using metals for your electrodes (they react too much with bacteria: poison, catalyzer etc...) you can use graphite or conductive polymer (without silver). I don't know if ...
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From what I understand, your main issue is connecting a solution in an electrical circuit without changing the composition of the solution due to electrochemical redox reactions.
So, there are two problems here. Firstly, passing direct current
(DC) changes the composition of the solution. Secondly, a solution cannot
be connected to the bridge like a ...
1
Dr. Larry Moran (Professor Emeritus in the Department of Biochemistry at the University of Toronto) has posted an nice article about the Free Energy of ATP Hydrolysis. Accordingly, some important concepts in biochemistry may be widely misunderstood and/or not well described in most textbooks. One of them is the free energy of ATP hydrolysis:
The traditional ...
1
The prime has nothing to do with whether a concentration is held constant. The prime is used to indicate that some species, typically protons or ions such as Mg, are being set to a value other than the standard 1M concentration for use in a reference free energy. Although the prime has been adopted by some in the biochemical community and was endorsed in ...
3
I believe you have misread the first referenced paper. What it says is that the $V_{max}$ and $K_m$ values for the forward and reverse reactions can be varied to optimize a property such as the maximum velocity (represented by $V_{max}$) in one direction, but are always constrained by the fixed value of $K_{eq}$.
The reason that the $K_m$ values (which are ...
3
Your question is based on a false premise. They don't stop when they run out of food. When you overproof the dough, there is still tons of edible carbohydrates left in the dough, mostly starch.
If you wait for the fermentation to stop on its own, this will happen not due to running out of food, but due to the accumulation of too much waste material. The ...
1
What yeast does:
glucose => etanol + carbon dioxide.
What lactobacilus does:
glucose => lactic acid
They usually don't find glucose around them, so they break down the starch first (starch is abundant in the dough).
They both also do other things, like making new cells from the ingredients they find around them, but these other things are of less ...
3
The first type of image is very easy to make. I would suggest Avogadro with POV-ray. Avogadro can be used to draw the structures (or open a file containing the information, like .mol2, .sdf etc.) and then high-quality images can be generated using POV-ray.
To do this, install Avogadro, then draw a structure, and then File> Export > POV-ray. A new ...
14
Flours contain a diverse array of carbohydrates which vary depending on the specific type of flour (wheat, rye, teff, etc). There will usually be a lot of starch (itself having variable amounts of different types of branching), some small mono and oligosaccharides (again of varying types) and "fiber", which is a broad term for polysaccharides that ...
10
From the introduction in a paper on the different lactic acid bacteria (LAB) cultures in sourdough:
Sourdough LAB give rise to the characteristic qualities of several kinds of foods (flavor, texture, taste, and shelf life) by producing metabolites such as lactic acid, acetic acid, and ethanol. However, it is not easy to control sourdough LAB fermentation, ...
1
You should investigate several pH and study the effect of time on the fluorescence spectra. One cannot quote single values without mentioning the wavelengths of excitation and emission.
pH can alter the state of ionization and it can also cause hydrolysis of the sugar unit.
You need to collect three different types of spectra at each pH, say from pH 2 to 12....
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I'm assuming we can neglect differences due to radioactivity/radioisotopes in biological systems.
Hydrogen vs Deuterium
The kinetic isotope effect - the difference in reaction rates and reactivity for different isotopes of the same element - is well known for hydrogen and its two stable isotopes protium and deuterium. For example levels of deuteration above ...
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Can sugars dissolve in liquid ammonia?
Yes, according to Ref.1, liquid ammonia is used to extract sugars in sugar-beet chips:
5.88 kilograms of sugar-beet chips having a moisture content of 5.4 percent and a saccharose content of 68 percent (calculated on the dried substance) are treated in an autoclave of 50-litre capacity with 18 kilograms of liquid ...
1
I would not expect significant differences in the chemical properties (reactivity) of these lead isotopes, the differences in atomic weight being as you point out very small. There are reports that claim an effect. Ref 1 for instance makes such a claim, but there is no plausible mechanism presented to explain the reported isotopic discrimination. Double ...
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