METABOLISM

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METABOLISM

• An Introduction

Ir. Irfan D. Prijambada, M.Eng., Ph.D.
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REFERENCES

• Albert L. Lehninger. 1982. Principles of
  Biochemistry. Worth Publishers, Inc.
  New York.

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METABOLISM
Highly coordinated and purposeful cell activity,
in which many multienzyme systems cooperate
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FUNCTIONS OF METABOLISM

• Obtain chemical energy from the degradation of
  energy-rich nutrients from the environment or
  from captured solar energy
• Convert nutrient molecules into building block
  precursors of cell macromolecules
• Assembly building blocks into cell components
• Form and degrade biomolecules required in
  specialized functions of cells

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THE CYCLE OF CARBON AND OXYGEN
PHOTOSYNTHETIC AUTOTROPH
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THE CYCLE OF NITROGEN
N2 atmospheric
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METABOLIC PATHWAYS ARE PROMOTED BY SEQUENTIAL
ENZYME SYSTEMS
A
LINEAR
CIRCULAR
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METABOLISM

• CATABOLISM, degradative phase of metabolism
  accompanied by release of free energy
• ANABOLISM, synthetic phase of metabolism which
  requires input of free energy

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RELATIONSHIP BETWEEN Catabolism and Anabolism
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THE USES OF CHEMICAL ENERGY IN CELLS

• BIOSYNTHESIS
• CONTRACTION AND MOTILITY
• ACTIVE TRANSPORT
• TRANSFER OF GENETIC MATERIAL

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THREE STAGES CATABOLISM

• DEGRADATION OF LARGE BIOMOLECULES INTO BUILDING
  BLOCK MOLECULES
• DEGRADATION OF BUILDING BLOCK MOLECULES INTO A
  COMMON DEGRADATION PRODUCT
• DEGRADATION OF A COMMON DEGRADATION PRODUCT INTO
  SIMPLE, SMALL END PRODUCTS

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FIRST STAGE OF CATABOLISM
Proteins
Amino acids
Poly saccharides
Glucose
Lipids
Glycerol, Fatty acids
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SECOND STAGE OF CATABOLISM
Amino acids
Glucose
Pyruvate
Acetyl Co-A
Glycerol, Fatty acids
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THIRD STAGE OF CATABOLISM
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CATABOLISM ANABOLISMDIFFERENCE
DIVERGENCE
CONVERGENCE
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DIFFERENT PATHWAY OF CATABOLISM ANABOLISM
CATABOLISM
ANABOLISM
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PATHWAYS OF CATABOLISM ANABOLISM
A
A
B
C
D
E
F
F
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REGULATIONS OF METABOLISM

• CHANGING ENZYME ACTIVITY, through Allosteric
  system
• CHANGING ENZYME ACTIVITY, through Hormonal
  regulation
• CHANGING ENZYME CONCENTRATION, through Induction
  and Inhibition of enzymes synthesis

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REGULATION BY CHANGING ENZYME ACTIVITY THROUGH
ALLOSTERIC SYSTEM
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GLUCOSE
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REGULATION BY CHANGING ENZYME ACTIVITY THROUGH
HORMONAL REGULATION
Active Glycogen Phosphorylase
Glucose
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REGULATION BY CHANGING ENZYME CONCENTRATION
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METHODS OF STUDYING METABOLISM

• In vivo and in vitro identification
• Auxotrophic mutants study
• Tracing study

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AUXOTROPHIC MUTANTS STUDY
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FIRST STAGE CATABOLISM OF PROTEINS
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FIRST STAGE CATABOLISM OF POLYSACCHARIDES
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FIRST STAGE CATABOLISM OF LIPIDS

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GLYCOLYSIS
ADP
ATP
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GLYCOLYSIS
ADP
ATP
D-FRUCTOSE 1,6-P
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GLYCOLYSIS
NADH H
P
NAD
ADP
ATP
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GLYCOLYSIS
ADP
ATP
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ANAEROBIC CONVERSON OF PRUVATE
NADH H
NAD
H2O
CO2
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AEROBIC CONVERSON OF PRUVATE
NADH H
NAD
CITRIC ACID CYCLE
CO2
Co-A
CO2 NADH H
ADP
O2
ATP
H2O
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THE DISCOVERY OF CITRIC ACID CYCLE

• Albert Szent-Gyorgyi found Succinate, Fumarate,
  Malate and Oxalacetate in animal tissue
• Albert Szent-Gyorgyi found that Succinate,
  Fumarate, Malate and Oxalacetate stimulate
  oxygenconsumption by muscle

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THE DISCOVERY OF CITRIC ACID CYCLE

• The Organic Acids found by Albert Szent-Gyorgyi

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THE DISCOVERY OF CITRIC ACID CYCLE

• Hans Krebs found that the 4 organic acids
  stimulate oxidation of pyruvate by suspensions of
  minced pigeon-breast-muscle
• Hans Krebs found Citrate, cis-Aconitate,
  Isocitrate,and a-Ketoglutarate also stimulate
  oxidation of pyruvate

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THE DISCOVERY OF CITRIC ACID CYCLE

• The Organic Acids found by Hans Krebs

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THE DISCOVERY OF CITRIC ACID CYCLE

• Hans Krebs also found that other organic acids
  have no effect
• Hans Krebs also found that Malonate inhibits
  oxidation of pyruvate by suspensions of minced
  pigeon-breast-muscle
• Hans Krebs also found that Citrate was
  accumulated in a reaction of Pyruvate and
  Oxalacetate

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REMEMBERSUBSTRATE COMPETITION
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THE DISCOVERY OF CITRIC ACID CYCLE

• Logical conversion of Hans Krebs

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THE DISCOVERY OF CITRIC ACID CYCLE

• Logical conversion of Hans Krebs

INHIBITED BY MALONATE
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THE DISCOVERY OF CITRIC ACID CYCLE

• Logical conversion of Hans Krebs

H2O
Coenzyme A



H
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SUMMARY OF THE CONVERSION
Cis Aconitate
Isocitrate
a-Ketoglutarate
Citrate
Succinyl co-A
Acetyl co-A
Oxalacetate
Succinate
Malate
Fumarate