You can investigate the effect of temperature on enzyme activity in the lab. Watch this video to see the correct procedure for an experiment showing how temperature affects the action of catalase on hydrogen peroxide. Temperature is a measure of how much kinetic energy molecules have. As the temperature is increased enzyme activity increases to a maximum value at the optimum temperature around 37 o C for most human enzymes.
As the temperature is increased above the optimum temperature enzyme activity decreases. It is said that one might adversely affect his investment in a show quality Siamese Cat by letting the cat be exposed to unusual temperatures. For example, if the cat is exposed to weather that is too cold, too much of the coat may turn dark.
So we can see that temperature plays a major role in the function of enzymes. For this reason, doctors have long been concerned about patients having very high fevers.
Doctors have also long been concerned with the opposite extreme when the body temperature is too low hypothermia. This is equally dangerous and also can be life-threatening. It is difficult to understand why we have been very concerned about extremely high or extremely low temperatures, but frequently appear to not even consider the effects of milder aberrations in body temperature.
If fever and hypothermia are two life-threatening extremes of a continuum, then it is only logical and reasonable that less severe alterations can cause less severe, but never-the-less significant problems.
Studies have shown that when an enzyme-dependent chemical reaction is monitored for how well it takes place at various temperatures, the lower the temperature, the slower the chemical reaction. As the temperature is increased, the reaction rate will go faster with each increase until it reaches its optimum reaction rate. If the temperature is increased too much, the rate of reaction will diminish due to denaturing or change in shape of the enzyme.
See Diagram Different enzymes work best at different temperatures and the functions of some are more greatly affected by changes in body temperature than others. As it turns out, the enzymes that are most affected by changes in body temperature are also often the enzymes that catalyze some of the more expendable bodily functions. Therefore, when the metabolism slows down, people often develop dry skin, unhealthy nails, dry hair, hair loss, irritability, poor recall, fluid retention, decreased sex drive, and up to 60 other puzzling and, until now, baffling symptoms.
The temperature at which a particular enzyme functions the best depends on its structure. And its structure depends on its coding as dictated by the genetic code found in the DNA of the chromosomes.
The genetic code is what permits the great variation in hair color, height, appearance, weight, hand size, etc. On the other hand, some factors differ very little from one person to another, such as the important enzymes for life. This is evidenced by the fact that some of the routine blood tests doctors do in an annual physical include tests for liver enzymes. Effect of temperature on reaction rate.
Over a period of time, enzymes will be deactivated at even moderate temperatures. Lower temperatures lead to slower chemical reactions. Enzymes will eventually become inactive at freezing temperatures but will restore most of their enzyme activity when temperatures increase again, while some enzymes lose their activity when frozen.
The temperature of a system is to some extent a measure of the kinetic energy of the molecules in the system. Collisions between all molecules increase as temperature increases. This is due to the increase in velocity and kinetic energy that follows temperature increases. With faster velocities, there will be less time between collisions. This results in more molecules reaching the activation energy, which increases the rate of the reactions.
Since the molecules are also moving faster, collisions between enzymes and substrates also increase. Thus the lower the kinetic energy, the lower the temperature of the system and, likewise, the higher the kinetic energy, the greater the temperature of the system.
As the temperature of the system is increased, the internal energy of the molecules in the system will increase. The internal energy of the molecules may include the translational energy, vibrational energy and rotational energy of the molecules, the energy involved in chemical bonding of the molecules as well as the energy involved in nonbonding interactions.
Some of this heat may be converted into chemical potential energy.
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