Enzyme
What is Enzyme
Enzyme Activity
How Enzymes Work
Factors affecting enzyme activity
Michaelis-Menten Theory
Fisher's Template Theory
Enzymes are specific proteins that accelerate the speed of chemical reactions in the body
Enzyme Classification & Enzyme Nomenclature
Biocatalyst : A molecule that accelerates a chemical reaction without being altered itself (Enzyme are not change)
Most of enzymes are protein
E+S <===> ES ----> ES + P
Enzyme’s function class
catalyze hydrolysis, with water serving as the acceptor of the group transferred.
Characteristics of Enzymes
Almost all enzymes are proteins
Heat labile ; Change form from liquid to solid (change protein)
Lock and Key model
catalyze lysis of a substrate, generating a double bond ; these are non-hydrolytic, nonoxidative elimination reaction.
Active site has a fixed , The substrate has a shape that fits the enzyme active site to form ES (enzyme-substrate complex)
Enzyme Inhibition
catalyze group-transfer, a portion of the substrate molecule usually binds covalently to the enzym or coenzyme
catalyze structure change within a single molecule (isomerization reaction) they are among the simplest enzymatic reactions.
catalyze oxidation-reduction reaction,most of these enzymes are referred to as dehydrogenase.
catalyze ligation of two substrates, ligases are usually referred to as synthetases.
Water-soluble
Be precipitated by protein precipitating reagents
Koshland's Induced Fit Theory
Induce Fit Model
Hand and Glove
Enzyme Applications
1. Reversible enzyme inhibition
2.Irreversible enzyme inhibition
Oxidoreductases
Allosteric Enzymes and Isoenzymes
1.1Competitive inhibitionr, Cl
• Inhibitor molecules are competing with the
normal substrate molecule for binding to the active site of the enzyme
• The inhibitior is a structural analog of the substrate
Contain 16% weight as Nitrogen
2.1 Noncompetitive inhibitor,Non Cl
• The inhibitor usually binds to a different domain on the enzyme,
other than the substrate binding site (El or ESI complex)
• The inhibitors have no structural resemblance to the substrate
Transferases
Enzyme Kinetic
Rubber industry
Pulp & Paper production
Starch industry
Cleaning products
Amylase, Amyloglucosidase, Glucoamylase, Glucose isomerase
Hydrolases
1.2 Uncompetitive inhibitor, UnCl
• Inhibitor binds only to enzyme-substrate
complex (ES-complex); but not to the free enzyme
• The inhibitors have no structural resemblance to the substrate
Catalase
V = Vmax[S] / Km + [S]
Amylase, Catalase, Laccase
Protease, Alpha-amylase, Lipase, Cellulase
E + S <=k1,k2=> ES --k2--> E + P
Lyases
Isomerases
Kinetic parameters
Kcat = Vmax / [E]t = k2
Ligases
Ammonium sulfate or Trichloroacetic acid
Enzyme Structure
The active site contains substrate binding site and catalytic site , is the shape of a three-dimensional cleft that is composed of amino acids from different residues of the primary amino acid sequence.
Type
The enzyme binds better or less with the substrate, an additional site of enzyme for an effector or modulator to bind to resulting in conformation change of active site or substrate binding site.
Substrate binding site
Disease indicators
Therapeutic drugs
surface area of the enzyme structure concave which fit the molecules of the substrate to bind.
Amylase
Creatine phosphokinase
Glutamic oxaloacetic transferase (GOT)
Glutamic pyruvic transaminase(GPT)
Active site or Catalytic site
Amylase
Trypsin and Chymotyrpsin
Allosteric enzyme
Isozymes or Isoenzymes
Allosteric site or Regulatory site