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Everything posted by BabcockHall

  1. Would you please say a bit more about good packing and column geometry? With respect to gradients and ion-exchange, I have seen a book the recommended short, broad columns over taller columns. But I don't know whether or not this carries over to affinity columns.
  2. Did you use any other information besides titration to find the identities of the two amino acids? I may be misunderstanding the question, but it might help to think about what glycine could take away.
  3. The manufacturer claims that 5-10 mg of protein binds per mL of resin.
  4. The donation of the nitrogen & hydrogen atoms and the concomitant production of fumarate takes place in two steps overall. One way to think about the second step is that it is simply an elimination reaction. A proton is lost from what was the beta-carbon of aspartate, and -NH3(+) is the leaving group, which departs from the alpha-carbon.
  5. Apologies, I misread your question, and I was pointing the way toward answering a different question. Aspartate is also used as a donor in the biosynthetic pathway that produces inosine monophosphate (check the two steps in the synthesis of AICAR) and in the urea cycle. I disagree that a side chain is necessarily more reactive and can think of some examples to illustrate this. However, I am not sure what makes one nitrogen donor used in one reaction and a different nitrogen donor used in another.
  6. Remember that cells must balance the biosynthesis of AMP and GMP. Does that help?
  7. I would not assume any particular value for Vmax. Instead I would rearrange the Michaelis-Menten equation into the form v/Vmax = (S)/{KM + (S)}. This means that the velocity one calculates will be relative to Vmax. I decided to avoid using concentration brackets in this comment, because I think that they might be causing the unwanted strikethroughs.
  8. I am familiar with some kinds of protein chromatography, but I now have to run a nickel column for the first time. The protein of interest bears a histidine tag, and uur protein is believed to be a dimer or possibly a tetramer of identical subunits. As is typical the nickel column is the first step after sonication of E. coli cells. How do I choose the best volume of gel to use? If I use too little, there will be loss of the protein in the load and wash. If I use too much, the protein is more dilute, and in some sense I am wasting gel. At first glance I can see that one issue is the need to estimate what fraction of soluble cell protein is the protein of interest. I might be tempted to estimate this as being no more than 20% of the soluble protein. A second issue is capacity of the gel, and based on my general knowledge of protein IEX chromatography it occurs to me that there might be some variation from one protein to another, based upon accessibility of the his tag.
  9. I am not sure what you mean by "absorbed topically via the sun."
  10. The short answer is that oxidation of food creates a proton motive force which is coupled to the synthesis of ATP from ADP and phosphate. It takes several chapters worth of lectures in biochemistry to provide a detailed explanation. I would be hesitant to bring heat directly into this discussion.
  11. I assume that you are referring to Serum glutamic pyruvic transaminase, also known as alanine aminotransferase. We cannot provide medical advice on this forum; that is best done by consulting your physician. You may find this link helpful in terms of background reading. https://www.summitmedicalgroup.com/library/adult_health/tst_sgpt_tst/
  12. Protein is an absolutely essential part of our diet. Without it, we would go into negative nitrogen balance.
  13. A good place to start might be to count carbon atoms and see whether any have been lost or added upon conversion to the products.
  14. https://www.statnews.com/2020/04/29/gilead-says-critical-study-of-covid-19-drug-shows-patients-are-responding-to-treatment/ Patients taking remdesivir recovered more quickly than those taking a placebo. Business Insider and CNN have stories.
  15. Muscle cells undergoing anaerobic consumption of glycogen produce more pyruvate than they can consume aerobically via the TCA cycle. The pyruvate is instead converted into pyruvate. Your second sentence implies that there is an additional way to make lactate, but there isn't.
  16. Are enzymes equally active at all pH values, or do they have an optimum pH? Does the balanced reaction produce/consume protons? The mechanism that you drew implies the answer. In other words if one used unbuffered water, would the pH of the water gradually change with time. With respect to why convert pyruvate into lactate, there are several ways to think about it. If a muscle cell did not, what would happen to the ratio of NAD to NADH within that cell?
  17. You might also ask which would pass through the plastic and which would not.
  18. John, If you are correct, then whoever made the drawing must have been smoking something.
  19. If you are looking for a basic reference book, you might find Fundamental Concepts of Bioinformatics by Krane and Raymer to be helpful, in that one of the authors is a biologist and the other a computer scientist. It is a bit out of date, but it is inexpensive.
  20. Something to bear in mind is that formal charges and oxidation numbers are both tools to help us keep track of electrons and charges. They make different assumptions about which atom owns the electrons.
  21. Please give us your thoughts first, and perhaps we can help. I would start by ruling out some choices.
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