New answers tagged

-2

You are correct. A particle could be another answer for an atom because that's where the smallest form of matter resides. Particles that makeup atoms are electrons, protons, and neutrons.... and particles that makeup those particles are considered quarks, or, buckyballs. Some of this was discovered by two scientist from Rice University Houston, TX sometime ...


0

I tell a true story about myself. In my senior year of college, I took as an elective, a course in Pre-engineering Physics. At that point in my studies, I had already taken a lot of math (Advanced Calculus, Linear Algebra, Statistics, Theory of Differential Equations,..., and even graduate-level credit in Numerical Analysis, Numerical Methods,...). To my ...


7

I think you're looking for the word: particle. ... a particle (or corpuscule in older texts) is a small localized object to which can be ascribed several physical or chemical properties such as volume, density or mass. They vary greatly in size or quantity, from subatomic particles like the electron, to microscopic particles like atoms and ...


3

Given your hypothesis that the three $\mathrm{p}K_\mathrm{a}$'s are dependent on one another and that experimentally you do not seem to be able to identify which histidines are protonated and which are not at any given time, it would seem that the simplest model to use is that of a triprotic acid such as citric acid. The triple HH equation model you used is ...


32

The classic catch-all term is molecular entity, often abbreviated to just entity. There's a Wikipedia page for it, which references the IUPAC Gold Book entry. Quoting from the latter: Any constitutionally or isotopically distinct atom, molecule, ion, ion pair, radical, radical ion, complex, conformer etc., identifiable as a separately distinguishable ...


0

The data look as if you have simply done a titration of histidine, with a first pKa at around 6, and another one at around 8.5 - 9. This is exactly what is expected from the tabulated values for histidine : pKa = 6.04 and 9.09. Why are you not satisfied about these measurements ? Your results are in perfect agreement with predictions form the tabulated ...


0

It makes no sense to solve for different pKa´s. They are constants specific to the acid groups of Histidine. Furthermore, the HH-equation describes the fraction of (in your case) dissociated acid in one acid/base equilibria. So if you sum the three steps, your Y-axis for one thing, has to go from 0 to 3. Just off the top of my head, it seems a better ...


0

"I am trying to understand why Nitrogen in Ammonia is a proton acceptor." I am going to modify your question slightly: it is a proton acceptor in aqueous solution. Water, being the solvent of life and being very common on Earth, is generally the most pertinent solvent. Ammonia is a proton acceptor, or if you prefer an electron-pair donor, in water. "...


3

Since you are asking about vitamins vs. minerals, I assume what you mean by mineral is a "dietary mineral" (as opposed to the more typical meaning of mineral, which is a naturally-occurring inorganic compound). So: A dietary mineral is an element that is essential for life (e.g., K, Ca, Fe, Se, Cr, P, I, Cl, Mo, etc.), and is required in small quantities. ...


1

Dynamics can mean many things, and not all proteins undergo extensive conformational changes during their lifetime. Some are fairly rigid in solution. XRD or NMR data represents an average over the conformations of a protein construct sampled under experimental conditions. A protein construct is a variant of the protein, selected to allow expression and ...


4

Nitrogen is more electronegative than hydrogen hence N will pull electrons towards itself. Hence not a good candidate to donate electrons! Yet it makes bonds with hydrogen, as do other electronegative elements (think of hydrogen chloride and water). So polar bonds form in all kind of molecules. lets take the case of Oxygen O=O, here each Oxygen atom has ...


9

There is a clear explanation and figure showing this in the following reference: Anton Gorkovskiy, Kent R. Thurber, Robert Tycko, Reed B. Wickner, PNAS 2014, 111 (43) E4615-E4622. A parallel beta sheet is one where the direction from N- to C-termini on adjacent strands run in a parallel direction (rather than antiparallel). In-register means that each ...


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