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How to measure enzyme activity?

How to measure enzyme activity? Topic: The first part of protein synthesis is an example
June 16, 2019 / By Kaylee
Question: doing a lab where i take yeast, which has enzyme sucrase, and let it break down table sugar, sucrose. i could measure glucose production but i'm not sure how. ketone/glucose strips won't work i think. i could also measure co2 production, i heard that could be done with measuring pH. explain? i could also measure the expansion/raising of the yeast/sugar solution over time, in a test tube. how? which is the best/easiest/cheapest?
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Best Answers: How to measure enzyme activity?

Hortense Hortense | 7 days ago
Well... enzymes are organic catalysts which speed up the rates of bio-chemical reactions. Enzymes generally work best in acidic media; which provide an optimum atmosphere for their activities (lowering the activation energy) of reactant organic molecules. Enzymes are known to catalyze about 4,000 biochemical reactions. A few RNA molecules called ribozymes catalyze reactions, with an important example being some parts of the ribosome.Synthetic molecules called artificial enzymes also display enzyme-like catalysis Enzyme activity can be affected by other molecules. Inhibitors are molecules that decrease enzyme activity; activators are molecules that increase activity. Many drugs and poisons are enzyme inhibitors. Enzyme Activity is also affected by temperature, chemical environment (e.g., pH), and the concentration of substrate. Some enzymes are used commercially, for example, in the synthesis of antibiotics. In addition, some household products use enzymes to speed up biochemical reactions (e.g., enzymes in biological washing powders break down protein or fat stains on clothes; enzymes in meat tenderizers break down proteins, making the meat easier to chew). My biology teacher also once mentioned that some enzymes work on the principle of Le Chatelier's Principle in a way... but the general factors are the ones i listed above. Hope this helps.
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Hortense Originally Answered: Clarify enzyme activity (umol/mg/min) these units?
Well, you or your professor certainly have made this confusing but it doesn't need to be. Enzyme activity is generally given as moles/unit time, e.g. per min. The specific activity of the enzyme would incorporate the mg protein of the enzyme. So, you might have something like nmoles/mg/min. It is, of course, possible to use molarity, if you know the volume of the solution in which the enzyme reaction takes place. So, you could then have nM/min or nM/mg/min. Again, the use of mg assumes you know how many mg of enzyme protein you have. Now, as for the double reciprocal plot, you are correct that it plots 1/v as a function of 1/S, and the Y intercept is the reciprocal of the Vmax, given in units of nmole/min, nmole/mg/min, or nM/min or nM/mg/min. Again, using mg assumes you know how many mg of enzyme protein you have. Hope all this now makes more sense. Let me know.

Edith Edith
It's simple!! To measure the rate of enzyme activity you leave it to the professionals who know how to do it
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Edith Originally Answered: How Could I Measure DNA changes in E. Coli?
Genetic mutations would not be seen on a gel. Though if you were to use restriction enzymes which cut DNA at certain sequences, the mutation of the DNA may cause a change to occur that will result in either the lack of or the addition of a restriction site. For example - If a restriction enzyme (RE) cut at GATAT, you could add it to the E. Coli and it would cut at all the normal sites. This could then be run on a gel to see the normal distribution of fragments (separated by size of course) This would be your control. Then following injection of your substances you could again use the same RE and get your fragments and run them on a gel to see if their are any diferences. If you cause a mutation from something like CATAT to GATAT you would have made a new cut site and thus a new size fragment that is likely to show up on your gel. There are more intense ways of doing this using genomic and cDNA libraries, one technique is called subtractive hybridization and it would most likely be helpful but only if you have a lot of time on your hands. But in the meanwhile look it up on google or wikipedia.
Edith Originally Answered: How Could I Measure DNA changes in E. Coli?
Gel electrophoresis isn't going to show you the types of mutations that you're going to induce. It only shows you relatively large changes in size. And the changes that you might make are going to be too small to see that way. Besides, a bacterial chromosome is way too big to resolve adequately in standard agarose gel electrophoresis. If you want to proceed with this, I would suggest using a phenotypic assay rather than a molecular assay. It's a lot simpler and doesn't require very sophisticated tools. One idea would be to use a pigmented strain of bacteria like S. marcescens. Expose the bacteria to a mutagen (such as UV light) and then see if you can mutate the pigmentation gene. You'll have to do a kill-curve to get the right dose of mutagen (ie: length of UV exposure) that will cause mutations without killing them. You basically plate the bacteria out, then expose them to the UV light. You'll also need a no-exposure control. Vary the length of exposure among your plates. With a long enough exposure, you'll get fewer colonies compared to your control as the bacteria die. Right before that point where things start to completely die out, you will hopefully see a higher proportion of non-pigmented bacteria. That's a mutation that you caused, and you don't have to wait forever to see it. You'll have to be careful with this experiment. Something that can cause mutations in bacteria can do it in you too. Use proper technique in a dedicated laboratory, and get a teacher that knows what they are doing to help you. Don't do this in your kitchen at home!

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