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About BabcockHall

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    bioorganic chemistry

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  1. We are zooming, too. I am trying to learn how to use a Wacom Intuos, but it's the old dog/new tricks problem.
  2. BabcockHall


    HCl is soluble in many solvents. I used to buy a solution of at least 1 M in dioxane IIRC.
  3. BabcockHall


    It would not be a true solution; it would be heterogeneous. It could be that the problem is imperfect, as opposed to being a trick question. As someone who has written my fair share of homework problems, I can say that it easy to overlook difficulties like this. Nevertheless, the amount of HCl needed to neutralize it is still something that could be calculated.
  4. BabcockHall


    The calcium hydroxide should come into solution as one adds more HCl. I doubt that it is a trick question.
  5. You wrote, "An optical density of samples with different protein content constituted from 0.0237 to 0.0933." Is this correct? One problem that I see is that if your unknown has a larger absorbance than 0.0933, you will be doing an extrapolation, not an interpolation. I generally filter the Bradford solution the same day as I use it. When I want the highest accuracy, I prepare a standard graph on the same day as the unknown.
  6. Thank you; that is very helpful. I think that I had been assuming implicitly that the two antibodies (soluble versus immobilized) recognized the same epitope. I now wonder whether the antibody at the Test position versus the gold-particle labeled antibody recognize the same or different epitopes. Perhaps the answer is different, depending on which test is used.
  7. link Good Morning Everyone, I have been studying various forensic test kits for body fluids, and a number of them from Abacus Diagnostics or Independent Forensics use lateral diffusion immunochromatography. In a sandwich format the antigen forms a complex with both the soluble, labeled antibody and the antibody immobilized onto a membrane at the test (T) position. I can see how this could easily work with a protein such as hemoglobin, which is a tetramer of two alpha and two beta subunits. It is less clear how this assay works with human salivary alpha-amylase, which is a monomer from what I can gather. In other words I can see how the sandwich forms when there are multiple epitopes, but it is less clear to me what is happening when there might be only one epitope.
  8. Try expressing [ES] in terms of [E] and then proceeding with the differential equation.
  9. There is an alternate derivation that assumes that E, S, and ES are in quasi-equilibrium. It is actually an easier derivation than steady-state.
  10. You might look at the book Criminalistics by Richard Saferstein.
  11. SDS PAGE denatures proteins, and not every protein that is denatured can be renatured. If you need active enzymes and you want to separate by molecular weight, then gel filtration might be an appropriate technique. However, it is often the case that obtaining a pure protein requires more than one method of separation.
  12. My own experience is that the shape of the standard curve depends upon the identity of the protein. However I generally put little trust in absorbance values of greater than 1.0 in the Bradford assay, even using a research-grade instrument, let alone one that is not. The problem is that there is not as much excess Bradford reagent as one moves higher in protein concentration. A standard curve should be made, preferably with the same protein that is being assayed.
  13. As far as I am aware, protons only flow in one direction, outside to inside. The key to how the flagellar motor rotates in both directions may lie in the flexibility of FliG.
  14. I don't know much about MotA/MotB other than there was a nice genetic suppression study done on the generation of torque some years back. Can you explain what you mean by symmetric?
  15. My working hypothesis is that the flagellar rotor can rotate in either direction because FliG has multiple conformations owing to what might be termed hinges. I am unaware that ATP synthase has a similar property.
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