8/3/2019 Biochemistry Lecture 6
http://slidepdf.com/reader/full/biochemistry-lecture-6 1/78
Study of Enzymes &
Coenzymes
Lecture No. 6
8/3/2019 Biochemistry Lecture 6
http://slidepdf.com/reader/full/biochemistry-lecture-6 2/78
8/3/2019 Biochemistry Lecture 6
http://slidepdf.com/reader/full/biochemistry-lecture-6 3/78
8/3/2019 Biochemistry Lecture 6
http://slidepdf.com/reader/full/biochemistry-lecture-6 4/78
8/3/2019 Biochemistry Lecture 6
http://slidepdf.com/reader/full/biochemistry-lecture-6 5/78
8/3/2019 Biochemistry Lecture 6
http://slidepdf.com/reader/full/biochemistry-lecture-6 6/78
How important are enzymes?
Enzymes are essential to sustain life becausemost chemical reactions in biological cells wouldoccur too slowly, or would lead to different
products, without enzymes. A malfunction (mutation, overproduction,
underproduction or deletion) of a single criticalenzyme can lead to a severe disease.
Enzymes work by lowering the activation energyof a reaction, thus allowing the reaction toproceed much faster.
8/3/2019 Biochemistry Lecture 6
http://slidepdf.com/reader/full/biochemistry-lecture-6 7/78
8/3/2019 Biochemistry Lecture 6
http://slidepdf.com/reader/full/biochemistry-lecture-6 8/78
8/3/2019 Biochemistry Lecture 6
http://slidepdf.com/reader/full/biochemistry-lecture-6 9/78
Terminologies Substrate ± substance reacted upon by an enzyme
Apoenzyme ± is an enzyme without its cofactor; it is the proteinmolecule to which a coenzyme will bind to produce the holoenzyme.
Ex. RNA polymerase
Holoenzyme ± the active and operative form of an enzyme. This isthe complete fully functioning enzyme. It is the combination of anapoenzyme with its cofactor.
Proenzymes ± are inactive precursors of enzymes. Ex. Zymogen,pepsinogen
Kinase ± substance used to activate the proenzyme.
Coenzyme is an organic non-protein molecule that is functional artof an enzyme. They are generally defined as cofactors.
Antienzyme ± is a substance that neutralizes or counteracts the
action of an enzyme or they refer to an inhibitory enzyme or anantibody to an enzyme that retards, inhibits, or destroys enzymicactivity.
Isoenzyme or isozymes are enzymes that differ in amino acidsequence but catalyze the same chemical reaction (LDH1-5)
8/3/2019 Biochemistry Lecture 6
http://slidepdf.com/reader/full/biochemistry-lecture-6 10/78
8/3/2019 Biochemistry Lecture 6
http://slidepdf.com/reader/full/biochemistry-lecture-6 11/78
Class Class Name Examples by trivial name
1 Oxidoreductase Dehydrogenase, oxidase,
peroxidase, catalase
2 Transferase Kinase, transaminase,
transketolase
3 Hydrolase Esterase, peptidase,digestive enzymes
4 Lyases Decarboxylase, aldolase,
deaminase, fumarase
5 Isomerase Epimerase, mutase
6 Ligases Carboxylase, acetyl CoA
carboxylase
8/3/2019 Biochemistry Lecture 6
http://slidepdf.com/reader/full/biochemistry-lecture-6 12/78
8/3/2019 Biochemistry Lecture 6
http://slidepdf.com/reader/full/biochemistry-lecture-6 13/78
8/3/2019 Biochemistry Lecture 6
http://slidepdf.com/reader/full/biochemistry-lecture-6 14/78
8/3/2019 Biochemistry Lecture 6
http://slidepdf.com/reader/full/biochemistry-lecture-6 15/78
8/3/2019 Biochemistry Lecture 6
http://slidepdf.com/reader/full/biochemistry-lecture-6 16/78
8/3/2019 Biochemistry Lecture 6
http://slidepdf.com/reader/full/biochemistry-lecture-6 17/78
8/3/2019 Biochemistry Lecture 6
http://slidepdf.com/reader/full/biochemistry-lecture-6 18/78
8/3/2019 Biochemistry Lecture 6
http://slidepdf.com/reader/full/biochemistry-lecture-6 19/78
8/3/2019 Biochemistry Lecture 6
http://slidepdf.com/reader/full/biochemistry-lecture-6 20/78
8/3/2019 Biochemistry Lecture 6
http://slidepdf.com/reader/full/biochemistry-lecture-6 21/78
8/3/2019 Biochemistry Lecture 6
http://slidepdf.com/reader/full/biochemistry-lecture-6 22/78
8/3/2019 Biochemistry Lecture 6
http://slidepdf.com/reader/full/biochemistry-lecture-6 23/78
8/3/2019 Biochemistry Lecture 6
http://slidepdf.com/reader/full/biochemistry-lecture-6 24/78
8/3/2019 Biochemistry Lecture 6
http://slidepdf.com/reader/full/biochemistry-lecture-6 25/78
8/3/2019 Biochemistry Lecture 6
http://slidepdf.com/reader/full/biochemistry-lecture-6 26/78
8/3/2019 Biochemistry Lecture 6
http://slidepdf.com/reader/full/biochemistry-lecture-6 27/78
8/3/2019 Biochemistry Lecture 6
http://slidepdf.com/reader/full/biochemistry-lecture-6 28/78
8/3/2019 Biochemistry Lecture 6
http://slidepdf.com/reader/full/biochemistry-lecture-6 29/78
8/3/2019 Biochemistry Lecture 6
http://slidepdf.com/reader/full/biochemistry-lecture-6 30/78
8/3/2019 Biochemistry Lecture 6
http://slidepdf.com/reader/full/biochemistry-lecture-6 31/78
8/3/2019 Biochemistry Lecture 6
http://slidepdf.com/reader/full/biochemistry-lecture-6 32/78
8/3/2019 Biochemistry Lecture 6
http://slidepdf.com/reader/full/biochemistry-lecture-6 33/78
8/3/2019 Biochemistry Lecture 6
http://slidepdf.com/reader/full/biochemistry-lecture-6 34/78
8/3/2019 Biochemistry Lecture 6
http://slidepdf.com/reader/full/biochemistry-lecture-6 35/78
8/3/2019 Biochemistry Lecture 6
http://slidepdf.com/reader/full/biochemistry-lecture-6 36/78
Other Coenzymes
Vitamin Coenzyme Function
Niacin NAD, NADP Oxidation-reduction
Pyridoxine Pyridoxal
phosphate
Various reactions involved in
AA activation
Lipoic acid Lipoamide Acyl group
activation;oxidation-reduction
Vitamin B12 Adenosylcobalamine
Isomerization and methyl
group transfer
8/3/2019 Biochemistry Lecture 6
http://slidepdf.com/reader/full/biochemistry-lecture-6 37/78
8/3/2019 Biochemistry Lecture 6
http://slidepdf.com/reader/full/biochemistry-lecture-6 38/78
8/3/2019 Biochemistry Lecture 6
http://slidepdf.com/reader/full/biochemistry-lecture-6 39/78
8/3/2019 Biochemistry Lecture 6
http://slidepdf.com/reader/full/biochemistry-lecture-6 40/78
8/3/2019 Biochemistry Lecture 6
http://slidepdf.com/reader/full/biochemistry-lecture-6 41/78
8/3/2019 Biochemistry Lecture 6
http://slidepdf.com/reader/full/biochemistry-lecture-6 42/78
8/3/2019 Biochemistry Lecture 6
http://slidepdf.com/reader/full/biochemistry-lecture-6 43/78
8/3/2019 Biochemistry Lecture 6
http://slidepdf.com/reader/full/biochemistry-lecture-6 44/78
8/3/2019 Biochemistry Lecture 6
http://slidepdf.com/reader/full/biochemistry-lecture-6 45/78
8/3/2019 Biochemistry Lecture 6
http://slidepdf.com/reader/full/biochemistry-lecture-6 46/78
8/3/2019 Biochemistry Lecture 6
http://slidepdf.com/reader/full/biochemistry-lecture-6 47/78
8/3/2019 Biochemistry Lecture 6
http://slidepdf.com/reader/full/biochemistry-lecture-6 48/78
8/3/2019 Biochemistry Lecture 6
http://slidepdf.com/reader/full/biochemistry-lecture-6 49/78
8/3/2019 Biochemistry Lecture 6
http://slidepdf.com/reader/full/biochemistry-lecture-6 50/78
8/3/2019 Biochemistry Lecture 6
http://slidepdf.com/reader/full/biochemistry-lecture-6 51/78
Chymotrypsin (Spacefill)
8/3/2019 Biochemistry Lecture 6
http://slidepdf.com/reader/full/biochemistry-lecture-6 52/78
8/3/2019 Biochemistry Lecture 6
http://slidepdf.com/reader/full/biochemistry-lecture-6 53/78
8/3/2019 Biochemistry Lecture 6
http://slidepdf.com/reader/full/biochemistry-lecture-6 54/78
8/3/2019 Biochemistry Lecture 6
http://slidepdf.com/reader/full/biochemistry-lecture-6 55/78
8/3/2019 Biochemistry Lecture 6
http://slidepdf.com/reader/full/biochemistry-lecture-6 56/78
8/3/2019 Biochemistry Lecture 6
http://slidepdf.com/reader/full/biochemistry-lecture-6 57/78
8/3/2019 Biochemistry Lecture 6
http://slidepdf.com/reader/full/biochemistry-lecture-6 58/78
8/3/2019 Biochemistry Lecture 6
http://slidepdf.com/reader/full/biochemistry-lecture-6 59/78
8/3/2019 Biochemistry Lecture 6
http://slidepdf.com/reader/full/biochemistry-lecture-6 60/78
8/3/2019 Biochemistry Lecture 6
http://slidepdf.com/reader/full/biochemistry-lecture-6 61/78
8/3/2019 Biochemistry Lecture 6
http://slidepdf.com/reader/full/biochemistry-lecture-6 62/78
8/3/2019 Biochemistry Lecture 6
http://slidepdf.com/reader/full/biochemistry-lecture-6 63/78
8/3/2019 Biochemistry Lecture 6
http://slidepdf.com/reader/full/biochemistry-lecture-6 64/78
8/3/2019 Biochemistry Lecture 6
http://slidepdf.com/reader/full/biochemistry-lecture-6 65/78
8/3/2019 Biochemistry Lecture 6
http://slidepdf.com/reader/full/biochemistry-lecture-6 66/78
8/3/2019 Biochemistry Lecture 6
http://slidepdf.com/reader/full/biochemistry-lecture-6 67/78
8/3/2019 Biochemistry Lecture 6
http://slidepdf.com/reader/full/biochemistry-lecture-6 68/78
Other Disorders of Enzymatic Defect
Metabolic Disorder Enzymatic defect
Agammaglobulinemia Inability to form gamma
globulins
Alkaptonuria Absence of hepatichomogentisic acid
Gout Excessive production of
uric acid
Hemohilia A, B, & G Deficiency of clotting
factors
Histidinemia Deficiency of histidase
8/3/2019 Biochemistry Lecture 6
http://slidepdf.com/reader/full/biochemistry-lecture-6 69/78
More Metabolic Disoders
Sickle cell anemia Presence of abnormalhemoglobins
Thalassemia Presence of abnormal
hemoglobins
Von Gierke¶s disease Deficiency of glucose-6-phosphatase
Porphyria Increased excretion of
uroporphyrins resulting to
lavender teeth, burgundy red
urine
Maple syrup disease Absence of decarboxylase
enzyme for branched chain
amino acids
8/3/2019 Biochemistry Lecture 6
http://slidepdf.com/reader/full/biochemistry-lecture-6 70/78
8/3/2019 Biochemistry Lecture 6
http://slidepdf.com/reader/full/biochemistry-lecture-6 71/78
8/3/2019 Biochemistry Lecture 6
http://slidepdf.com/reader/full/biochemistry-lecture-6 72/78
8/3/2019 Biochemistry Lecture 6
http://slidepdf.com/reader/full/biochemistry-lecture-6 73/78
8/3/2019 Biochemistry Lecture 6
http://slidepdf.com/reader/full/biochemistry-lecture-6 74/78
8/3/2019 Biochemistry Lecture 6
http://slidepdf.com/reader/full/biochemistry-lecture-6 75/78
8/3/2019 Biochemistry Lecture 6
http://slidepdf.com/reader/full/biochemistry-lecture-6 76/78
8/3/2019 Biochemistry Lecture 6
http://slidepdf.com/reader/full/biochemistry-lecture-6 77/78
S
8/3/2019 Biochemistry Lecture 6
http://slidepdf.com/reader/full/biochemistry-lecture-6 78/78
Summary Enzymes are biologic catalysts that increase the
rates of biochemical processes but are themselvesunchanged. Most (but not all) enzymes are proteins.
In enzyme catalysis, one or more substrates arebound at the active sites of an enzyme, to form theenzyme-substrate complex; products are thenreleased.
The rate of chemical reaction is determined byreactant concentration and by the rate constant.
All catalysts function by lowering the activationenergy for a reaction. In doing so, they do not affectchemical equilibrium but only increase rates.
Many enzymes utilize coenzymes in their functions;others require specific metal ions. A number of coenzymes are closely related to vitamins requiredin the diet.
Top Related