BabcockHall

There is controversy concerning whether or not a diet high in fructose is healthy. I cannot evaluate this question without a great deal more study, but I found a few links for those wishing to pursue the topic. Fructose metabolism in humans – what isotopic tracer studies tell us https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3533803/ Fructose, but not glucose, impairs insulin signaling in the three major insulin-sensitive tissues https://www.nature.com/articles/srep26149 Fructose Consumption in the Development of Obesity and the Effects of Different Protocols of Physical Exercise on the Hepatic Metabolism https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5409744/

In muscles and kidneys, hexokinase converts fructose into fructose 6-phosphate and enters into the hexose phosphate pool at this point; it can be converted into fructose 1, 6-bisphosphate (the first committed step of glycolysis) or be converted into glucose 6-phosphate. However, in liver fructokinase converts fructose into fructose 1-phosphate, which is cleaved into glyceraldehyde and dihydroxyacetone phosphate (DHAP) by an aldolase. DHAP is converted into glyceraldehyde 3-phosphate GAP by triosephosphate isomerase and enters into glycolysis in this way. Glyceraldehyde is separately phosphorylated to GAP and continues through glycolysis.

Fructose enters into glycolysis differently from glucose; it comes in later. IIRC there is an aldolase that is distinct from the aldolase that we associate with glycolysis, but the details escape me at the moment. Therefore, the regulatory controls which govern early glycolytic enzymes such as hexokinase and phosphofructokinase-1 are bypassed. Although glucose 6-phosphate and fructose 6-phosphate are easily interconverted by phosphohexoseisomerase, IIRC this is not the point at which the pathway from fructose joins glycolysis.

Did the double bond isomerize in a stereochemical (cis-trans) sense; did it move in a regiochemical sense; or did it do something else?

Esters can be made using dicyclohexylcarbodiimide and catalytic DMAP. Another method is to use oxalyl chloride to form the acid chloride. We have used the latter method successfully in the presence of a double bond.

Have you read the forum policies?

Please show us the work you have done so far. This will make it easier for us to help you.

Doing scientific research has almost no benefit to anyone unless one publishes the results, presumably in the form of a journal article. I have read many student laboratory reports, and I have read and written scientific papers. Writing well is a very difficult but very important skill to master. Part of writing clearly is thinking clearly.

Each E coli cell has about half a dozen flagella. They act as screw propellers. When all rotate in the same direction, the bacterial cell moves forward. When some rotate in one direction and others rotate in the opposite direction, the bacterium tumbles, and will then swim in a new direction. This is how chemotaxis occurs. The flagellum is powered by the proton motive force. I think of it as an electric motor of a sort. Other species are different in the specifics. One problem that the E. coli cell must solve is how to export the proteins and assemble the flagellum from its constituent proteins.

http://science.sciencemag.org/content/354/6319/1552.full This is a link to a paper on bacteriorhodopsin, which is a light-driven proton pump. It might give you a general picture of how protons and proteins interact. Groups such as Asp85 and Asp96 transiently bind to the proton that is being actively transported. This protein was put into artificial vesicles with ATP synthase. Light cause bR to create a proton gradient, which was able to drive the synthesis of ATP, an early demonstration that the Mitchell chemiosmotic hypothesis was correct. My understanding is that protons that are not bound to side-chains on a protein are frequently bound to buffering species. The concentration of free protons is small.

Unless the starch molecule has a defined number of glucose monomers, I don't see how it can have a single molecular weight. Polymers are not my strongest suit, but it might be possible to define an average molecular weight.

I am not aware of any paper that specifically addresses this question. There are experiments one could do. For example, it has been reported in the product literature from BioRad that bovine serum albumin gives about twice the response as egg albumin when both are at the same concentration in mg/mL.

A decrease in pH within a cell may manifest itself as an increase in the relative amount of H2PO41- to HPO42-. As a proton is actively transported across a membrane, there are side-chains that can bind and release protons. These include glutamate, histidine, and lysine residues.

I only have time for a quick comment right now. I have coached many people through the process of calculation of rates. A common error is to use the wrong volume when converting from absorbance per unit time into µmoles per minute. But if you are confident that you have done that correctly, then great.

Calculating the number of double bond equivalents (DBEs) is easy to do from the molecular formula, and doing so will give you some idea of the presence of double or triple bonds or rings that are present. As far as I can tell, the number of degrees of unsaturation is the same thing as the number of DBEs.

As far as I am aware, different fields have different conventions in expressing first-order processes. I don't know of any reason why one convention or another is used.

I think we would need more parameters, such as the two asymptotes. Possibly earlier papers in the series provides some information.

In this instance, I would take it that the compound is cAMP and that the column of data marked %max dose refers to how much cAMP is generated by a high concentration of the peptide, measured using a relative scale. Both 5 and 15 scored 100%. MT-II is only mentioned twice in the paper, and I am still working out what it means.

I would say that when compound 5 reaches 4.5 nM, it reaches its EC50, the midpoint between the effect at zero concentration, and the effect at saturation. If its concentration is, say 20-fold, above 4.5 nM (90 nM), then it is near saturation, and any further increase would have little effect. Qualitatively, the same holds true for compound 15, except that its EC50 means that it saturates at a much lower concentration. I am not sure what you mean by CMAX; however, one column in the table that you provided suggested to me that both compounds produce the same maximal effect at high concentration. I think that we would need to know the in vivo concentrations of 5 and 15 to be certain. Yet, if both are high relative to their EC50s, then I suspect that they will produce similar effects. https://www.graphpad.com/guides/prism/7/curve-fitting/reg_the_ec50.htm?toc=0&printWindow

@OP, What does the concept of saturation mean to you?

I recommend reading Motulsky and Christopoulos, p. 256 and p. 315. It is often the case that the response Y is graphed versus [agonist], where the latter is plotted on a logarithmic scale. If one wishes to set the Hill slope to unity, then one can fit to a three-parameter equation. Y = bottom + (top - bottom)/(1 + 10^log(EC50 - X)). If one wants to include the Hill slope as the fourth parameter, then the term (EC50 - X) should be multiplied by the Hill slope.The shape of this curve is sigmoidal, and its steepness is governed by the Hill slope.

This part of your comment provides some context. In order to answer the question, we may need to make the assumption that the concentrations in vivo are proportional to the dose. Let Y be the response and X be the concentration of agonist. One equation that can be used is Y = [(a - d)/(1 + (X/c)^b)] + d. The parameter a is lower asymptote or plateau; b is the slope factor; c is the concentration of agonist that provokes a response halfway between the baseline response and the maximum response; and d is the upper asymptote or plateau. The authors of the J. Med. Chem. paper may cited previous papers; therefore, I am not certain whether or not they used this equation. How does parameter c relate to your question?

First, we are not here to do your homework or your non-homework thinking for you. You are supposed to show some sort of effort. Second, you did a poor job presenting the question. Table 2 is cut off in your diagram. Third, why did you ask for someone with a knowledge of peptide pharmacokinetics? Pharmacokinetics could be defined as "the study of the time course of drug absorption, distribution, metabolism, and excretion". The question you are asking is not entirely unrelated to that field, but we don't have any information that bears on the pharmacodynamics of either compound (and in any case your opening post assumes identical pharmacokinetics). Fourth, the answer to your opening question could be found by thinking carefully about the reply you have already been given by CharonY. Your most recent answer suggests to me that you are not approaching this problem correctly. Consider the following hypothetical. Compound A has a value of EC50 of 1 nM. Compound B has a value of EC50 has a EC50 value of 10 nM. Suppose that both are present in vivo at 100 nM. What would you conclude?

That's just a restatement of what you said in your opening post. I expected more effort than you have put in so far, such as defining EC50, or saying that EC50 was measured by examining cAMP levels. I had to go to the original paper to learn that.

Calcium ions are one member of the class of chemical species called "second messengers," which respond to hormones, the first messengers. Calcium ions activate protein kinase C, among many other effects. My answer is intended to be very general.