Chapter 13:
Introduction to Enzymes
Voet & Voet:
Pages 469-481
Lecture 7 Biochemistry 2000 Slide 1
, Introduction
Virtually all biochemical reactions in an organism are mediated by
remarkable biological catalysts – enzymes
Enzymes are a category of protein that differ from ordinary chemical
catalysts in several respects
(1) Higher reaction rates
● several orders faster than equivalent chemical catalysts
● 106-1012 rate enhancement
(2) Milder reaction conditions
● low temperature, atmospheric pressure, narrow pH range, etc.
(3) Greater reaction specificity
● Narrow range of substrate and product specificities
● stereospecificity, lack of side products
(4) Capacity for regulation
● “fine” control of reaction rate
Lecture 7 Biochemistry 2000 Slide 2
, Substrate Binding
Substrate binding to a protein is governed by the
same noncovalent forces that apply to protein
structure
Binding sites are:
1) generally an indentation or cleft on the surface of the
enzyme molecule
2) complementary in shape (includes chirality) to the
substrate (geometric complementarity)
3) complementary in electrostatic surface potentials to the
substrate (electronic complementarity)
● charge or partial charge associated with each point along the
surface of a protein
Only complementary (geometric and electronic)
substrates bind to an enzyme binding site (via
noncovalent forces)
Lecture 7 Biochemistry 2000 Slide 3
Introduction to Enzymes
Voet & Voet:
Pages 469-481
Lecture 7 Biochemistry 2000 Slide 1
, Introduction
Virtually all biochemical reactions in an organism are mediated by
remarkable biological catalysts – enzymes
Enzymes are a category of protein that differ from ordinary chemical
catalysts in several respects
(1) Higher reaction rates
● several orders faster than equivalent chemical catalysts
● 106-1012 rate enhancement
(2) Milder reaction conditions
● low temperature, atmospheric pressure, narrow pH range, etc.
(3) Greater reaction specificity
● Narrow range of substrate and product specificities
● stereospecificity, lack of side products
(4) Capacity for regulation
● “fine” control of reaction rate
Lecture 7 Biochemistry 2000 Slide 2
, Substrate Binding
Substrate binding to a protein is governed by the
same noncovalent forces that apply to protein
structure
Binding sites are:
1) generally an indentation or cleft on the surface of the
enzyme molecule
2) complementary in shape (includes chirality) to the
substrate (geometric complementarity)
3) complementary in electrostatic surface potentials to the
substrate (electronic complementarity)
● charge or partial charge associated with each point along the
surface of a protein
Only complementary (geometric and electronic)
substrates bind to an enzyme binding site (via
noncovalent forces)
Lecture 7 Biochemistry 2000 Slide 3
