Enzymes
Enzymes catalyze nearly all the chemical reactions taking place in the cells of the body and increase the rate of reation by lowering the energy of aciation. Enzmes are biological catalysts and without them, these ractions take place at a rate far too slow for the pace of metabolism. All known enzymes are proteins, and are high molecular weight compounds made up principally of chains of amino acids linked together by eptide bonds.
The big deal with catalysts is that they are extremely efficient, very specific, regulatable and all of these properties can be related to protein nature of enzymes.
There are 6 categories of enzymes:
The rate of an enzyme-catalyzed reaction increases as the tempeature is raised. A ten degree centigrade rise in temperaturewill increase the activity of most enzymes by 50-100%. Enzymes are mostactive at an optimum temperature and lose activty at high temperatures. Enzymes also contain an optimum pH and lose actvity in low or high pH as tertiary structure is disrupted.
As substrat concentration increases the rate of the reaction increases until the enzyme eventually becomes saturated, giving maximum activiyt. If the amount of the enzyme is kept constant and the substrate concentration is then gradually increased then the reaction velocity will increase. An increase in enzyme concentratio causes an increase in teh reaction rate. At higher concentrations, teh rate is increased more slowly as the substrate would be completely saturated with enzymes.
Cofactors are substances that are essential in the catalytic activity of some enzymes. THye may alter the shape of an enzyme slightly to make the active stes function and ay coenzymes (organic molecules) or inorganic ions (metal ions-iron, magnesium or zinc). A cofactor that is tightly or even covalently bound is termed a prosthetic group. Coenzymes are organic molecules that are requird by certani enzymes to carry out catalysis. They bind to the active site of the enzyme and participate in catalysis (but are not the substrates of the reaction). Coensymes often function as intermedite carriers of electonrs, specific atoms or funtional groups that are transferred in the overall reaction. THey are produced in limited amounts and are recycled and reused, examples include NAD+ and NADP+
Isoenzymes catalyze the same reaction in different tissues in the body and can be used to identify the ogan or tissue invovled in damage or disease.
There are some chemical substances that reduce or completely prevent enzyme activity knwon as inhibitor. There are two different types of inhibiors competitive and non-competitive. With competitive inhibitors the substrate and inhibitor are chemically similar and the inhibitor occupies the active site and prevents the substrate from binding. With non-competitive inhibitors, the substrate and inhibitor are not similar and the inhibitor alters the shape o the active site.
Learn More
Enzymes: A fun Introduction
Enzymes and...Pac man?
Questions
Enzymes catalyze nearly all the chemical reactions taking place in the cells of the body and increase the rate of reation by lowering the energy of aciation. Enzmes are biological catalysts and without them, these ractions take place at a rate far too slow for the pace of metabolism. All known enzymes are proteins, and are high molecular weight compounds made up principally of chains of amino acids linked together by eptide bonds.
The big deal with catalysts is that they are extremely efficient, very specific, regulatable and all of these properties can be related to protein nature of enzymes.
There are 6 categories of enzymes:
- addition or removal of water: hydrolases and hydrases
- transfer of electrons: oxidases and dehydrogenases
- transfer of a radical (or groups of atoms): transglycosidases, transphosphorylases, transaminases, transmethylases and tranacetylases
- splitting or forming a C-C bond: Desmolases
- Changing geometry or structure of a molecule (rearrange atoms): Isomerases
- Joining two molecules through hydrolysis of pyrophosphate bond in ATP or other tri-phosphate: Ligases
The rate of an enzyme-catalyzed reaction increases as the tempeature is raised. A ten degree centigrade rise in temperaturewill increase the activity of most enzymes by 50-100%. Enzymes are mostactive at an optimum temperature and lose activty at high temperatures. Enzymes also contain an optimum pH and lose actvity in low or high pH as tertiary structure is disrupted.
As substrat concentration increases the rate of the reaction increases until the enzyme eventually becomes saturated, giving maximum activiyt. If the amount of the enzyme is kept constant and the substrate concentration is then gradually increased then the reaction velocity will increase. An increase in enzyme concentratio causes an increase in teh reaction rate. At higher concentrations, teh rate is increased more slowly as the substrate would be completely saturated with enzymes.
Cofactors are substances that are essential in the catalytic activity of some enzymes. THye may alter the shape of an enzyme slightly to make the active stes function and ay coenzymes (organic molecules) or inorganic ions (metal ions-iron, magnesium or zinc). A cofactor that is tightly or even covalently bound is termed a prosthetic group. Coenzymes are organic molecules that are requird by certani enzymes to carry out catalysis. They bind to the active site of the enzyme and participate in catalysis (but are not the substrates of the reaction). Coensymes often function as intermedite carriers of electonrs, specific atoms or funtional groups that are transferred in the overall reaction. THey are produced in limited amounts and are recycled and reused, examples include NAD+ and NADP+
Isoenzymes catalyze the same reaction in different tissues in the body and can be used to identify the ogan or tissue invovled in damage or disease.
There are some chemical substances that reduce or completely prevent enzyme activity knwon as inhibitor. There are two different types of inhibiors competitive and non-competitive. With competitive inhibitors the substrate and inhibitor are chemically similar and the inhibitor occupies the active site and prevents the substrate from binding. With non-competitive inhibitors, the substrate and inhibitor are not similar and the inhibitor alters the shape o the active site.
Learn More
Enzymes: A fun Introduction
Enzymes and...Pac man?
Questions
- describe the role of enzymes
- list the factors that affect the rte of an enzyme catalyzed reaction
- describethe effect of temperature on an enzyme catalyzed reaction
- explain the basic enzyme catalyzed reaction
- hat are coenzymes?