NEET BIOLOGY IMPORTANT NOTES- ENZYMES
Enzymes are proteinaceous, biocatalysts. First NEET BIOLOGY IMPORTANT NOTES Enzymes discovered by Buchne. Term enzyme was given by Kuhne. Zymase (from yeast) was the first discovered enzyme. (Buchner). The first purified and crystalized enzyme was urease (by J.B. Sumner) from Canavalia/Jack Bean (Lobia plant) Proteinaceous nature of enzyme was established by Northrop and Sumner.
- Enzymes are biocatalysts made up of proteins (except ribozyme), which increases the rate of biochemical reactions by lowering down the activation energy.
- First discovered ribozyme was L19 RNAase by T.Cech from rRNA of a protozoan Tetrahymena thermophila and RNAase P or Ribionuclease P by Altman in prokaryotic cell (Nobel prize).
General properties of Enzymes
- Large sized biomolecules, colloid nature with high molecular weight –
- Large size (equal to colloid particles) provide, more surface area so passes large no.of active site. Large number of substrate converted into product by one molecule of enzyme at a time.
- Highest molecular weight is of enzyme pyruvate dehydrogenase complex (46 lakh) participate in link reaction of respiration.
- Monomer unit of a enzyme is Amino acid
- Amino acids linked togather to form polypeptide chain
- Enzymes are polypeptide chains
- Most of enzymes arrange in tertiary structure of protein or globular proteins except enzyme(Quaternary st.)
- Tertiary structure of protein provides stability and water soluble nature to enzymes.
- synthesis of enzymes occurs on ribosomes under the control of genes
- Enzymes are specific for pH, temperature and substrate
- pH – The common pH range of enzymes activity is 6 – 8.
- Every enzyme works on specific pH, Pepsin-2.5 pH, Hydrolase-4-5,
- Rubisco, Pepcase-8.5 pH, Trypsin – 8.5 pH
- Common range of temperature for enzyme activity is 20 – 40°C
- Enzymes works on body temperature of organism not on environmental temperature.
- Enzymes of plants are affected by evironmental temperature change as plants does not show homeostasis.
- At low temperature enzymes become functionally inactive, at high temperature denatured.