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BabcockHall last won the day on October 15 2015

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About BabcockHall

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    bioorganic chemistry
  1. I would also post this at Chemical Forums. I do not recall seeing anything like this.
  2. A good place to start is by giving us your thoughts. What sort of scenarios do you have in mind?
  3. As one raises pH, transphosphorylation becomes more of an issue. What happens at low pH, loss (or perhaps epimerization) of glycosidic bonds?
  4. Did you store frozen, at refrigerator temperature, or at room temperature? From your initial post, it sounds as if you stored it frozen. My guess is that this is better than leaving it at room temperature, but I might have quick frozen the sample and stored it at -80 °C unless I had a better protocol. I cannot speak to the specific question of the best way to store RNA, but I can make some very general comments about freezing. One is that the pH of a buffer solution can change as the solution cools, and RNA is labile in basic conditions. Two is that there are shearing forces during the freezing process which can cause problems in some instances. Therefore, I would look into the use of cryoprotectants and fast freezing protocols for RNA. I do not have an explanation for the mass that you are seeing.
  5. The equilibrium constant for aspartokinase is not particularly favorable, but it is heavily regulated in E. coli.
  6. When delta-G is less than zero, a reaction is spontaneous, and when delta-G = 0, a reaction is at equilibrium. When delta-G° is negative, a chemical reaction has an equilibrium constant that is greater than one. This symbol, delta-G°, refers to standard state, meaning all reactants and products at 1 M in concentration. The two quantities do not provide the same information, and their values are often not the same number. That having been said, the in vivo values of delta-G are more difficult to obtain because one has to know the concentrations of reactants and products in vivo. If they are not available, one has no choice but to use delta-G° values in one's arguments. I think that "always" is a high bar, meaning that there could well be exceptions to any generalization. I would start by taking regulatory enzymes from glycolysis and gluconeogenesis (hexokinase, PFK-1, pyruvate kinase, pyruvate carboxylase, PEPCK, fructose 1,6-bisphosphatase, and glucose 6-phosphatase) and finding the values of Gibbs' free energy in a biochemistry textbook. Nelson and Cox or Metzer are my go-to sources, typically.
  7. Is this a homework problem? It is up to you to provide your answer (or at least make an attempt) before we help you. A good place to start on this problem is to give a few examples. It might also help to differentiate between delta-G and delta-G°'.
  8. What are your thoughts on these two questions? I'll give you a frame of reference for your first question: consider what would happen chemically to convert chymotrypsinogen into chymotrypsin. With respect to your second question, can you think of any reactions that require NADH as a reactant? EDT Think about reactions from glycolysis/gluconeogenesis that produce or consume NADH. Also there are at least three common fates of pyruvate that has been produced from glycolysis. Do any of these processes involve NADH?
  9. I now have a copy of Seber and Wild's book from the library, but it is written at a level which is not easy for me to follow. In the section that covers confidence intervals. they do not use the nomenclature that the ProStat manual does. In other words I cannot find terms like "supporting plane" and "univariate" in this book.
  10. @OP, This is just a guess, but were you asking because of an interest in mitochondrial depletion syndrome, which has been in the news recently? It seems that some forms of this disease are related to mutations in thymidine kinase 2 of mitochondria. This enzyme has a role in the salvage of deoxynucleotides, but I have not yet found a good review article.
  11. What is the simplest chiral alcohol that you can think of? How can one imagine linking an alcohol to an amino acid (which functional group on the amino acid would you chose)/
  12. Is this homework? What are your thoughts about how to do this?
  13. Of course insulin also brings about homeostasis by down-regulating the pathways in the liver that produce glucose: gluconeogenesis and glycogenolysis. Insulin stimulates the production of acetyl CoA from glucose. There is also interplay among leptin, NPY, and insulin, but I am not very familiar with it.
  14. Motulsky and Christopoulos Presented and compared three methods of generating confidence intervals: Asymptotic (Chapter 16), Monte Carlo (Chapter 17), and Model Comparison (F ratio or F test, Chapter 18). In chapter 19 they compare all three methods. Only the asymptotic method gives a symmetrical distribution.