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ENZYME KINETICS

B.SC. SEMESTER 4

MS. SUDIPTA SARKAR

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INTRODUCTION

  • TO DETERMINE THE RATE OF REACTION AND HOW IT CHANGES IN RESPONSE TO CHANGES IN EXPERIMENTAL PARAMETERS IS KNOWN AS ENZYME KINETICS

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  • SUBSTRATE CONCENTRATION AFFECTS THE RATE OF ENZYME CATALYSED REACTION

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  • IT IS TO MEASURE THE INITIAL RATE DESIGNATED AS V0

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CONT.

  • AT HIGHER SUBSTRATE CONCENTRATION INCREASES BY SMALLER AMOUNT IN RESPONSE TO INCREASES IN [S] . THE POINT REACHED BEYOND WHICH INCREASES IN IIAL VELOCITY ARE VANISHINGLY SMALL AS [S] INCREASES. THIS PLATEAU IS CLOSE TO MAXIMUM VELOCITY.

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  • THE ENZYME FIRST COMBINES REVERSIBLY WITH ITS SUBSTRATE TO FORM AN ENZYME SUBSTRATE COMPLEX IN A RELATIVELY FAST REVERSIBLE STEP:

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CONT.

  • THE ES COMPLEX BREAKS DOWN TO YIELD FREE ENZYME AND REACTION PRODUCT

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CONT.

  • ENZYME IS FIRST MIXED WITH EXCESS OF SUBSTRATE THERE IS AN INITIAL PERIOD THE PRE STEADY STATE DURING WHICH THE CONCENTRATION OF ES BUILDS UP

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  • THE REACTION QUICKLY ACHIEVES A STEADY STATE IN WHICH [ESREMAINS CONSTANT OVER.

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  • THIS IS REFERRED AS STEADY STATE KINETICS

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MICHAELIS MENTEN KINETICS

  • STEP 1: RATE OF FORMATION AND BREAKDOWN OF ES

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  • STEP 2: STEADY STATE ASSUMPTION

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CONT.

  • STEP 3:

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CONT.

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INTERPRETATION

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