Enzymes are vital important, because in their absence reactions in the cell would be too slow to sustain life.

 enzyme and substrate

Now lets ask ourselves some questions to easily bring up the definition of enzymes.

  • What is an enzyme?

 - Is a biological catalyst.

 

  • Why it is called a catalyst?

- Because it speeds up(catalysis) a chemical reaction.

 

  •   How does it catalysis a chemical reaction?

- It lowers the activation energy of the reaction and speeds up the reaction.

 

  • What does the term Biological stand for?

- Since the enzymes are protein molecules made by living cells.

 

  • Where do the enzymes function?

-they function within the cell or out of the cell.

  

Now we have to organize the answers we got above for the definition of the " enzymes".

 

Definition 

Enzymes are biological catalysts which are protein molecules made by living cells and function within or out of the cell and catalyst a chemical reaction by lowering the activation energy of the reaction.

 

 

Enzyme inhibitors

 Enzyme inhibitors are a variety of small molecules exist which can reduce the

rate of an enzyme controlled reaction.

There are 2 types of inhibitors:

  1.Competitive inhibitors.

  2.Non competitive inhibitor.

Enzyme Inhibitors 

The non competitive inhibitors can be considered into 2 types:

  1.Non competitive reversible inhibitors.

  2.Non competitive irreversible inhibitors.

 

Competitive inhibitors
(போட்டியுள்ள மீளக்கூடிய நிரோதி)

Non competitive reversible (போட்டியற்ற மீளக்கூடிய நிரோதி)

Non competitive irreversible (போட்டியற்ற மீளமுடியாத நிரோதி)

Compete for a position in the active-site with the substrate (கீழ்ப்படை.)

Does not compete

Does not compete

Has a similar structure to that of the substrate (கீழ்ப்படை)

No structural similarity to the substrate (கீழ்ப்படை)

No structural similarity to the substrate (கீழ்ப்படை)

Fit into the active-site (உயிர்ப்புத்தானம்)

Fit with the enzyme at a point other than its active site(allosteric site)

Fit with the enzyme at a point other than its active site(allosteric site)

Fit temporarily or reversible

Reversible

Irreversible

Does not affect the structure of the enzyme

Affects and changes the structure of the enzyme temporarily

Affects and changes the structure of the enzyme, but permanently

Increase in substrate concentration increase the rate of reaction

Increase in the substrate concentration does not affect the rate of reaction

Increase in the substrate concentration does not affect the rate of reaction

Does not make the enzyme ineffective as a catalyst

Does not make the enzyme ineffective as a catalyst

Makes the enzyme ineffective as a catalyst

Does not  cause the protein of the enzyme molecule to precipitate

Does not  cause the protein of the enzyme molecule to precipitate

Day cause the protein of the enzyme molecule to precipitate

eg: Malic  acid inhibits the function of succinic de-hydrogenase enzyme

Cyonade ion inhibits cytochrome-oxidase

Heavy metal ions

 


These are some examples for the enzyme which you will be studying in Unit-4, Nutrition. And I hope that you would have learnt this in O/L. remembering this would help you in future, if you are still a beginner in A/L Biology.

Enzyme

Produced In

Carbohydrate Digestion

Salivary Amylase

 

Pancreatic Amylase

 

Maltase

Lactase

Invertase

 

 

Salivary Gland

 

Pancreas

 

Small intestine

Small intestine

Small intestine

Protein Digestion

Pepsin

Rennin

Trypsin

Chymotrypsin

Peptidase

 

 

Stomach

Stomach

 

Pancreas

Pancreas

Small intestine

Nucleic acid Digestion

Nuclease

Nucleosidase

 

 

Pancreas

Pancreas

Fat Digestion

Lipase

 

Pancreas

 

Enzymes & Micro Organism

These are some enzymes and the Micro Organism which produce enzymes.

Many commercial industrial produces enzymes by various microorganisms using their microbial synthesis.

Below table shows some examples for the microbial synthesis of enzyme.

 

Enzyme

Micro Organism

  1. 1.1.Invertase or Sucrase

Saccharomyces cerevisiae

  1. 1.2.Amylase

Aspergillus niger

  1. 1.3.Protease

Aspergillus oryzae

  1. 1.4.Lipase

Rhizopus sp.

 

Glossary

  1. 1.1.Active site: Location on an enzyme where substrates fit and where catalysis occurs.
  2. 2.2.Activation energy: The energy, required to start a chemical reaction
  3. 3.3.Allosteric site: Location on an enzyme at which an inhibitor molecule fits.
  4. 4.4.Co-enzymes: Organic co-factors. Vitamins are a part of many co-enzymes.
  5. 5.5.Co-factors: Inorganic ions and organic non-protein molecules that help some enzymes function as catalysts.
  6. 6.6.Competitive inhibition:
  7. 7.7.Inhibitors:

 

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Posted: 3 years 11 months ago by sabeehah #9976
sabeehah's Avatar
what are activators?can u provide a detailed explaination?