What is enzyme's inhibited state?
365934
an enzyme is a protein which lowers the free energy needed for it's target molecule or molecules to change their structure. for example - adding a phosphate group to another molecule. there are many ways in which the body regulates the enzymes capacity - some ways are by altering the substrate level - usually more substrate results in higher capacity - note that the change is NOT linear.\nanother way is by regulating the genes coding for these enzymes - inhibiting such a gene will result in lower enzyme levels and thus the overall capacity will be lower. note that in this case, each enzyme will work at it's usual capacity.\nwhat you are asking about is another way of controlling the enzymatic capacity. there are two general ways in which other molecules change the enzymes capacity - it can be competitive inhibition - a molecule which binds to the target site on the enzyme and lowers it's chance of binding to its' target molecule. the other method of inhibition is non-competitive inhibition - in this way a molecule binds to a site other that the target site, causing a conformational change in the enzyme and thus changes the affinity of the enzyme to it's target molecule.\na slightly different mechanism is used only in enzymes which have several sub-units (separate proteins that bind to each other to make one active enzyme). these make up many of the enzymes in our body. the mechanism used here is called allosteric change (note that all other regulation mechanisms are at work in these enzymes as well). allosteric change involves a binding of a molecule to the allosteric site which changes the conformation of the enzyme. this change can activate the enzyme and make it work more effectively, or it can inhibit the enzyme.\nso... an enzyme can be active, and by various mechanisms (involving not only other molecules but also "breaking" of the enzyme into active parts, changes in pH, temperature and more) it can change it's capacity - it can be lowered, inhibited almost completely or increased.
694888
yes of course ..\n\nMany of the enzymes in our bodies work best at body temperature. At significantly lower temperatures the substrate molecules do not have enough kinetic energy for the reaction to take place even in the presence of the enzyme. At body temperatures significantly higher than normal, the enzyme will not work well because the kinetic energy from the molecules in the solution containing the enzyme is so high, that the enzyme's shape is pulled apart to he point that the enzyme is not able to properly function. \n\nIndeed the enzyme's structure may be so disrupted or denatured hat the enzyme molecule cannot return to its original shape. Indeed the danger of high fevers stems in large part from the potential damage to enzymes and other proteins from the high temperature
340411
Yes.  There is no rule that says an enzyme can only have one active site.  Usually when there is more than one active site, they alternate in some fashion (try doing a web search on "alternating sites mechanism"--you will find plenty of examples).\n\nIn theory, the enzyme could also serve to couple two different reactions occurring at separate active sites.  I can't think of any examples off the top of my head right now.
582504
Another important thing to note about an enzyme is that it isn't used up in the reaction, so it can be recycled over and over. An enzyme is a protein that helps in a chemical reaction to speed it up. Enzymes are very specific in the reactions that they will interact with. An enzyme will only catalyze its own reaction.
894951
Enzymes are chains of amino acids, thus being proteins, and are not living. They will continue to work until they have been denatured (change in conformational structures causing it to be inactive) at that point they are still around just not able to be used.
138243
Then the reaction that the enzyme was catalysing would slow down or totally stopped.
267166
B, its specific shape allows specific substrates to bind to the enzyme, thus catalyzing the reaction. If the enzyme DIDN'T have the specific shape, then the substrate would have to take a longer time to break their own bonds themselves.
497267
thatguybil has the explanation for competitive inhibition correct.  The Km will decrease as concentration of the inhibitor increases, but Vmax will generally not change.\n\nIn the case of uncompetitive inhibition, the apparent Vmax and Km will both decrease as the concentration of inhibitor increases.  Unlike noncompetitive inhibitors, which bind both the enzyme and the ezyme-substrate complex, uncompetitive inhibitors bind only to the enzyme-substrate complex.
394321
Well, there really isn't one answer to this. You have to think about the function of your enzyme and why it might or might not need multiple substrate/pH combinations.\n\nBear in mind that organisms often have different responses as a result of different stresses. Your enzyme could very well be sensing pH and using that to select a particular cell signalling pathway to deal with a particular stress. \n\nWork it out and you should have a nice paper.
640976
Enzymes have an optimal pH and temperature for their function.  I cannot draw a graph here, so I'll just explain it.  If you graphed enzyme function on the y axis (left side) and temperature or pH on the x asix (bottom) you would see that the enzyme has very little function at the lowest temperature (or pH).  As you increase temp. or pH, the enzyme function will also begin to increase.  Eventually you reach the enzyme's optimal temp. or pH, and at that point, the enzyme funtion cannot increase any more.  If you continue to increase temp. or pH, you will see the enzyme function start to decrease.\n\nThis occurs because enzymes require a certain conformation to function correctly.  If the temp. or pH is not optimal, then the enzyme's shape will be slightly altered from it's optimal conformation.  The altered enzyme may still function, but not as well as the optimal conformation does.\n\nTry Googling "enzyme temperature graph" and then look for images.  You should find a graph similar to what I've described.
318515
It inhibits an enzyme from destroying Nitrous oxide which is needed for an erection to take place.
743400
Enzymes accelerate the rate of the reaction. When the enzymes are heated, they reach their optimum point. They are activated and thus produce a faster rate of reaction.
772757
Enzymes can only take (generally) very specific substrate.  A dissimilar substrate will usually not undergo any enzymatic alteration.  An enzyme's shape is what determines its function.  Altering the shape of the enzyme will usually prevent it from working on its substrate.
675098
An enzyme is a protein that catalyzes, or speeds up, a chemical reaction. The word comes from the Greek ένζυμο, énsymo, which comes from én ("at" or "in") and simo ("leaven" or "yeast"). Certain RNAs also have catalytic activity, but to differentiate them from protein enzymes, they are referred to as RNA enzymes or ribozymes.\n\nEnzymes are essential to sustain life because most chemical reactions in biological cells would occur too slowly, or would lead to different products without enzymes. A malfunction (mutation, overproduction, underproduction or deletion) of a single critical enzyme can lead to a severe disease. For example, the most common type of phenylketonuria is caused by a single amino acid mutation in the enzyme phenylalanine hydroxylase, which catalyzes the first step in the degradation of phenylalanine. The resulting build-up of phenylalanine and related products can lead to mental retardation if the disease is untreated.\n\nLike all catalysts, enzymes work by providing an alternate pathway of lower activation energy of a reaction, thus allowing the reaction to proceed much faster. Enzymes may speed up reactions by a factor of many millions. An enzyme, like any catalyst, remains unaltered by the completed reaction and can therefore continue to function. Because enzymes do not affect the relative energy between the products and reagents, they do not affect equilibrium of a reaction. However, the advantage of enzymes compared to most other catalysts is their sterio-, regio- and chemoselectivity and specificity.\n\nEnzyme activity can be affected by other molecules. Inhibitors are naturally occurring or synthetic molecules that decrease or abolish enzyme activity; activators are molecules that increase activity. Some irreversible inhibitors bind enzymes very tightly, effectively inactivating them. Many drugs and poisons act by inhibiting enzymes. Aspirin inhibits the COX-1 and COX-2 enzymes that produce the inflammation messenger prostaglandin, thus suppressing pain and inflammation. The poison cyanide inhibits cytochrome c oxidase, which effectively blocks cellular respiration.\nEnzymes are usually specific as to the reactions they catalyze and the substrates that are involved in these reactions. Shape, charge complementarity, and hydrophillic/hydrophobic character of enzyme and substrate are responsible for this specificity
504313
an enzyme is a protein that catalyzes, or speeds up, a chemical reaction. and there is a numerical classification of enzymes called the enzyme commision number, or ec number, based on the chemical reactions they catalyze (enzyme-catalyzed reactions).\n\nec1: oxidoreductases - to catalyze oxidation-reduction reactions; transfer of H or O atoms from one substance to another\n\nec2: transferases - transfer of a functional group from one substance to another wherein the group may be methyl-, acyl-, amino- or phospate group\n\nec3: hydrolases - formation of two products from a substrate by hydrolysis\n\nec4: lyases - non-hydrolytic addition or removal of groups from substrates. C-C, C-N, C-O or C-S bonds may be cleaved\n\nec5: isomerases - intramolecule rearrangement such as isomerization changes within a single molecule\n\nec6: ligases - join together two molecules by synthesis of new C-O, C-S, C-N or C-C bonds with simultaneous breakdown of atp
520742
The activity of an enzyme is tested by measuring how quickly it degrades the substrate or how quickly product is formed in an enzyme-catalyzed reaction.  This can be measured using spectrophotometry.\n\nHowever, you cannot compare these activities in samples with different protein concetrations because the increased enzyme activity may only be due to the fact that there are more enzymes contained in the sample.  Therefore, you divide the activity by the total amount of protein in the sample.  This way you can compare the activities of different samples and get an idea of how well the enzyme is functioning in different environments.\n\nAs for the calculations, just asking me to do them is giving me nightmares about my biochemsitry course I just completed.  If you already have the activity, you divide it by the total mass of protein present in the sample to get the specific activity.  If you are doing a purification procedure, the more you purify the sample, the less protein will be present and as long as the enzyme of interest remains in the assay samples the specific activity should go up.
353146
It is an enzyme that can counteract the damagging effects of oxygen in tissues. Like the vitamin E.