how do enzymes work?

Question

factors that affect activity

Answer 1

Enzymes are proteins that catalyze, or accelerate, biochemical reactions, a broad range of chemical reactions, which take place in all living organisms. Enzymes are biochemical catalysts. In these reactions, the molecules at the beginning of the process are called substrates, and the enzyme converts these into different molecules. Almost all processes in the cell need enzymes in order to occur at significant rates. Since enzymes are extremely selective for their substrates and speed up only a few reactions from among many possibilities, the set of enzymes made in a cell determines which metabolic pathways occur in that cell.

Like all catalysts, enzymes work by providing an alternative path of lower activation energy for a reaction and thus dramatically accelerate the rate of the reaction. Some enzymes can make their conversion of substrate to product occur many millions of times faster. As with all catalysts, enzymes are not consumed by the reactions they catalyze, nor do they alter the equilibrium of these reactions. However, enzymes do differ from most other catalysts by being much more specific. Enzymes are known to catalyze about 4,000 biochemical reactions.Not all biochemical catalysts are proteins, since some RNA molecules called ribozymes can also catalyze reactions.

Enzyme activity can be affected by other molecules. Inhibitors are molecules that decrease enzyme activity, and activators are molecules that increase activity. Drugs and poisons are often enzyme inhibitors. Enzyme activity is also affected by temperature, 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 steak tenderizers breakdown long meat proteins, making them easier to chew).

Enzymes are usually very specific as to which reactions they catalyze and the substrates that are involved in these reactions. Complementary shape, charge and hydrophilic/hydrophobic characteristics of enzymes and substrates are responsible for this specificity. Enzymes can also show impressive levels of stereospecificity, regioselectivity and chemoselectivity.

Some of the enzymes showing the highest specificity and accuracy are involved in the copying and expression of the genome. These enzymes have "proof-reading" mechanisms. Here, an enzyme such as DNA polymerase catalyses a reaction in a first step and then checks the product is correct in a second step. This two-step process results in average error rates of less than 1 error in 100 million reactions in high-fidelity mammalian polymerases. Similar proofreading mechanisms are also found in aminoacyl tRNA synthetases and ribosomes.

Some enzymes that produce secondary metabolites are described as promiscuous, as they can act on a relatively broad range of different substrates. It has been suggested that this broad substrate specificity is important for the evolution of new biosynthetic pathways

Recent investigations have provided new insights into the connection between internal dynamics of enzymes and their mechanism of catalysis. An enzyme's internal dynamics are described as the movement of internal parts (e.g. amino acids, a group of amino acids, a loop region, an alpha helix, neighboring beta-sheets or even entire domain) of these biomolecules, which can occur at various time-scales ranging from femtoseconds to seconds. Networks of protein residues throughout an enzyme's structure can contribute to catalysis through dynamic motions. Protein motions are vital to many enzymes, but whether small and fast vibrations or larger and slower conformational movements are more important depends on the type of reaction involved. These new insights also have implications in understanding allosteric effects, producing designer enzymes and developing new drugs.

see:
http://en.wikipedia.org/wiki/Enzyme_assay
http://en.wikipedia.org/wiki/Enzyme_inhibitor
http://en.wikipedia.org/wiki/Enzyme_kinetics

Answer 2

The activities of enzymes are determined by their three-dimensional structure.

Most enzymes are much larger than the substrates they act on, and only a very small portion of the enzyme (around 3–4 amino acids) is directly involved in catalysis. The region that contains these catalytic residues, binds the substrate and then carries out the reaction is known as the active site. Enzymes can also contain sites that bind cofactors, which are needed for catalysis. Some enzymes also have binding sites for small molecules, which are often direct or indirect products or substrates of the reaction catalyzed. This binding can serve to increase or decrease the enzyme's activity, providing a means for feedback regulation.

Like all proteins, enzymes are made as long, linear chains of amino acids that fold to produce a three-dimensional product. Each unique amino acid sequence produces a unique structure, which has unique properties. Individual protein chains may sometimes group together to form a protein complex. Most enzymes can be denatured—that is, unfolded and inactivated—by heating, which destroys the three-dimensional structure of the protein. Depending on the enzyme, denaturation may be reversible or irreversible.

Answer 3

How do Enzymes Work?
An enzyme is a protein molecule that speeds up chemical reactions. Each enzyme has a unique shape that determines its function. One enzyme works on one type of substrate.

The enzyme, Amylase has a shape that allows its to wrap around starch(substrate) and cut it up into individual glucose units.

Answer 4

Factors taht affect activity are pH, Temperature, concentration of enzyme, concentration of substrate. Enzymes work like a key, that fit into a keyhole and open different possibilities for a chemical. without enzymes we would not be able to do much of anything.

Answer 5

An enzyme is a protein molecule that speeds up chemical reactions. Each enzyme has a unique shape that determines its function. One enzyme works on one type of substrate.

The enzyme, Amylase has a shape that allows its to wrap around starch(substrate) and cut it up into individual glucose units.

Check out the website, it's very interesting!

Answer 6

An enzyme can catalyse certain reactions under the correct conditions.
They do so by enabling one or more reactants making them prone to reaction.
The enzyme will have a functional area where a reactant will be activated, this is normally a function group which will either donate or accept electrons from the reagent. This action will activate the reactant making it more susceptible to another reactant.

Answer 7

they speed up or enable reactions, but they can also stop reactions using feedback controls (see feedback inhibition). Enzymes drive most of your body's functions and emotions. They are the driving force of everything you do, and essentially, your survival - Enzymes need a very specific active site to bind to before they can be effective - active sites are more or less puzzle peices, you need the exact match

Answer 8

Heat; enzymes are proteins which must fold up in a certain way to work. Too much heat & they denature or start breaking up; hence the reason your body must stay at around 37.5 degrees celcius.

Answer 9

enzymes goes n bind d substrate in lock n key manner... vich inhibits d function of tat cell or organ

Answer 10

I don't know, i'm not an enzyme.