What is the effect of extreme change in pH on enzyme activity?

Answer 1

Enzymes are picky with pH levels, as they are with every thing else. They have an optimal level at which they work the best, and anything above or below that level, their activity begins to slow down until they shut down all together. (Which is referred to as denaturing the enzyme)

As an example, salivary amylase requires a pH of around 7. Since salivary amylase is located in your mouth, the pH in its environment is perfect, but if you were to swallow the enzymes and they were to arrive in your stomach (which has a pH of around 2) the enzyme would be denatured and would no longer work.

Don't become confused like I was when I first learned this though, each enzyme requires its own pH level. While salivary amylase becomes denatured at a pH level of 2, pepsin thrives at that level.

Answer 2

The effects of high or low pH of enzyme activity can be determined by its amino acid sequence and the conditions of the solution it finds itself in. Enzymes are three dimensional, and are therefore tertiary proteins. The acidity of a solution can affect the tertiary structure of the protein, making it more or less accessible to the substrates/ligands (ligands are molecules that affect enzyme activity but are not processed by the enzyme).

In most cells enzymes acting in the cytosol and mitochondrion have pH optima of around 7.2 (physiological pH); however, some enzymes in these compartments actually work better at lower pH, which occurs when the cells are stressed. The vacuole and apoplastic space (between plasma membrane and cell wall) of plant cells is much more acidic, therefore enzymes acting there have pH optima between 3-5. In the human digestive tract there are enzymes operating at basic pH (mouth and intestine) and highly acidic pH (stomach).

The effect of pH depends on the "native" conditions that the enzyme is optimized to use.

Answer 3

obviously just like everything else its all relative to what ur talking about Certain enzymes are denatured by extreme pH and temp and some will thrive at the same levels. Each enzyme has an optimal range: pepsin works best at a pH of 2 and resides in ur fat stomach while trypsin floats in ur pile of meat intestines and works at a pH of 8. Any deviation from optimal temp range will decrease productive (reaction rates) so if u get aids and ur body temp gets to like 105-106 ur phaucked. any half wit knows this sheait botch. GL

Answer 4

If the pH is higher of lower than the enzyme is used to, it can cause the enzyme to change shape. The folding and 3D shape of an enzyme is crucial to the way it functions. The change in pH can lead to the enzyme being denatured so that it cannot be returned to its original shape.

Answer 5

Since enzymes are proteins (containing a number of acid and basic groups), they are very sensitive to changes in pH. Different enzymes have different Optimum pH values. This is the pH value at which the bonds (ionization states of the amino acid residues involved in the catalytic activity of the enzyme) within them are influenced by H+ and OH- Ions in such a way that the shape of their Active Site is the most complementary to the shape of their Substrate. At the Optimum pH, the rate of reaction is at an optimum. Extreme changes in pH can cause enzymes to denature and permanently lose their function.

PH affect:

(1) the binding of the enzyme to substrate,

(2) the catalytic activity of the enzyme,

(3) the ionization of the substrate,

(4) the variation of protein structure.

Some enzymes like hydrolytic enzymes such as Pepsin and Chymotrypsin effectively operate at a very low acidic pH. Other enzymes like alpha amylase found in the saliva of the mouth operate most effectively at near neutrality whereas lipases will function at basic pH values.

Answer 6

Any change in pH will cause a decrease in enzyme activity. This decrease in the rate of reaction is because it will change the shape of the enzyme molecules.