This document provides an overview of enzyme mechanisms. It begins with an introduction to enzymes and their functions as biological catalysts. The main topics covered include the substrate that enzymes act upon, active sites and allosteric sites, factors that influence enzyme activity such as temperature and pH, and theories for how enzymes catalyze reactions including the lock and key and induced fit models. The document concludes with references and an acknowledgment.

1. ENZYME MECHANISM
GUIDED BY-
SUMANA KOTIAN
Dept. of Chemistry
Yuvaraja’s College
Autonomous, Mysore
PRESENTED BY-
SHRYLI K S
2ND Semister
Molecular Biology
27th March 2018

2. CONTENTS
• Introduction
• Enzymes
• Substrate
• Active site and Allosteric site
• Enzyme specificity
• Factors effecting enzyme activity
• Mechanism of enzymes catalysed reaction
• Adsorption theory
• Lock and key model
• Induced fit model
• Conclusion
• References
• Acknowledgement
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3. INTRODUCTION
Fig 1: Anselme Payen
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4. ENZYMES
• A substance
produced by a living
organism which acts
as a catalyst to bring
about a specific
biochemical
reaction.
Fig 3: An enzyme reaction.
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5. SUBSTRATE
• The reactant molecules in the enzyme based
reaction.
Fig 4: Substrate
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6. ACTIVE SITES AND ALLOSTERIC SITE
Fig 5: Active site of an enzyme. Fig 6: Allosteric site of an enzyme.
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7. ENZYME SPECIFICITY
ENZYME
Fig 8: Specificity of an enzyme.
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8. FACTORS EFFECTING ENZYME
ACTIVITY
• Physical factors
•Cofactors, Coenzymes &
Prosthetic Group
•Enzyme inhibitors
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9. PHYSICAL FACTORS
Fig 9: Reaction v/s Temperature
graph of enzymes.
Fig 10: Reaction v/s pH graph of
enzymes.
Fig 11: Reaction v/s Concentration
of substrate graph of enzymes.
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10. COFACTORS, COENZYMES &
PROSTHETIC GROUP
Fig 12: Cofactors Fig 13: Coenzymes

11. INHIBITORS
INHIBITORS
COMPETITIVE
INHIBITION
UNCOMPETITIVE
INHIBITION
NON-COMPETITIVE
INHIBITION
REVERSIBLE IRREVERSIBLE

12. MECHANISM OF ENZYME CATALYSED
REACTION
• Thermodynamic Changes
• Processes at the active sites

13. Fig 14: Energy v/s Reaction graph on enzymes.
THERMODYNAMIC CHANGES

14. PROCESSES AT THE ACTIVE SITE
• Covalent catalysis
• Acid-base catalysis
• Catalysis by proximity
• Catalysis by bond-strain
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15. ADSORPTION THEORY
Fig 15: Adsorption Theory of enzymes.
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16. LOCK AND KEY MODEL
Fig 16: Lock and Key Model of enzymes. Fig 17: Hermann Emil Fischer
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17. INDUCED FIT MODEL
Fig 19: Induced fit.
Fig 18: Danial Koshland
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18. CONCLUSION
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19. REFERENCES
• Biochemistry for the Pharmaceutical Science. C P Woodbury Jr,
Paperback publications, Chicago. 2012, 500 pg.
• Lehninger Principles of Biochemistry. David L Nelson & Michael M
Cox. Hardcover. Palgrave Macmillan publication Australia. 5th
edition, 2008, 1100 pg.
• Enzymes, the Physics and Chemistry of Life. Pfeiffr J. 1955, Simon &
Schuster Publications, New York. 288 pg.
• https://en.wikipedia.org/wiki/Enzyme
• https://en.wikipedia.org/wiki/Catalysis
• http://www1.lsbu.ac.uk/water/enztech/mechan.html
• http://www.worthington-
biochem.com/introbiochem/specificity.html
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20. ACKNOWLEDGEMENT
I express my sincere gratitude to my guide, Sumana Kotian for her
guidance throughout the preparation of my seminar. I thank the
department of Molecular Biology for providing me this opportunity
to present my seminar. Thank you all for your patience.
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