Explain Characteristic of enzyme catalysis and SHAPE SELECTIVE CATALYSIS.
Answers
1)Since a particular enzyme acts as a catalyst for a particular reaction only, therefore they are highly efácient and specific in nature.
2)The enzymes can catalyse a particular reaction with a certain temperature and pH ranges only. They become inactive outside the optimum temperature and pH ranges
3)Activators and co-enzymes are those substances that tend to increase the rate of catalyses by the enzyme
4)Inhibitors and poisons are those substances that tend to decrease the activity of enzyme during enzyme catalysis.
Characteristic of SHAPE SELECTIVE CATALYSIS.
A catalytic reaction which depends upon the pore structure of the catalyst and on the size of the reactant and the product molecules is called shape-selective catalysis. For example, catalysis by zeolites is a shape-selective catalysis. The pore size present in the zeolites ranges from 260-740 pm. Thus, molecules having a pore size more than this cannot enter the zeolite and undergo the reaction.
Answer:
Enzyme catalysis is the increase in the rate of a process by a biological molecule, an "enzyme". Most enzymes are proteins, and most such processes are chemical reactions. Within the enzyme, generally catalysis occurs at a localized site, called the active site.
Charecteristics:
Some characteristics of enzymes are as follows:
(1) Enzymes are unique in nature and show varying degree of specificities, while they are highly specific for a particular substrate. The active site of an enzyme shows a strong affinity for a specific substrate, and further slightly changes the conformation of substrate. It is known as an "induced fit" to accommodate the reacting substrate, and this induced fit further leads to a stabilized transition state to lower the activation energy of the reaction. The same catalyst cannot be applied in more than one reaction. Stereo specificity means that enzymes can detect the different optical isomers and react to only one type of isomer. Group specific enzymes refer to those catalyzing a group of substances with specific groups.
(2) Enzymes are extremely efficient and possess great catalytic power, transforming about 100 to 10,000 substrate molecules into product per second and proceeding from 103 to 108 times faster than the uncatalyzed reaction. Enzymes do not affect the equilibrium constant in spite of the increase in the conversion rate of substrate into product. The number of substrate molecules converted to product is called the turnover number. Only a small number of enzymes are typically required under normal cellular conditions to catalyze a chemical reaction.
(3) Enzymes itself remain unchanged during the reaction. Although the amino acid residues of enzyme may get broken or form covalent bonds with the substrate, it can typically reform those broken bonds or separate with substrates, allowing the enzyme to bind with more substrates.
(4) Enzymes can be allosterically regulated by a variety of means, but the activity of the catalysts cannot be controlled. Sometimes, activators and coenzymes are necessary for enzymatic catalysis, which are helpful to increase enzyme potency due to the presence of a weak bond between the enzyme and a metal ion. Inorganic substances are often known as activators. Additionally, there are also molecules that can allosterically inhibit enzyme function by modifying its conformational shape. The use of many drugs is related to their action as enzyme inhibitors in the body.
(5) The effectiveness of an enzyme catalyst could achieve maximum at its optimum temperature. Both the enhancement and decrease of the optimum temperature result in a decrease in catalytic activity.
SHAPE SELECTIVE CATALYSIS:
A catalytic reaction which depends upon the pore structure of the catalyst and on the size of the reactant and the product molecules is called shape-selective catalysis. For example, catalysis by zeolites is a shape-selective catalysis.