Proteins and Enzyme Action

Pregunta	Respuesta
Two types of Proteins	Globular and Fibrous
What are Globular proteins?	Soluble proteins with specific 3D shape e.g Hormones, Enzymes, Haemoglobin, Antibodies
What are Fibrous proteins?	Strong, insoluble, flexible material E.g Collagen and Keratin
Building Blocks for Proteins?	Amino Acids
Structure of Amino Acid?	-Central Carbon -Carboxyl (COOH) Group to right -Amino Group to Left -Hydrogen above -R Group below Image: Amino Acid Structure (binary/octet-stream)
How do amino acids differ?	The R group varies
How do amino acids join together?	Condensation reaction between Carboxyl group and amino group. Peptide Bond
What does two amino acids form?	Dipeptide
Monomers of Proteins	Amino Acids
What are Proteins made up of?	One or more Polypeptides
Define the Primary Structure	Sequence of amino acids - Polypeptide chain
Define the Secondary structure	Hydrogen bonds between the amino acids form coils - alpha helix OR Beta pleated sheets
Define the Tertiary structure	The coiled structures coil more due to hydrogen and ionic bonds between amino acids. Disulphide bridges between Cystine amino acids If the structure only have ONE polypeptide bond this is the final 3D structure
Define the Quaternary Structure	Several different polypeptide chains bonded together Final 3D structure for proteins made of more than one polypeptide chain ( Haemoglobin, Insulin, Collagen
Test for Protein	Biuret test Add Sodiumhydroxide solution Add Copper (II) Sulfate solution Protein turns from blue to purple
Define an Enzyme	AN biological Catalyst Speed up the rate of reaction - lower activation energy
What makes a Enzyme specific?	Specific active shape Only complementary substrates can bind to it
Structure of Enzymes	-Rough spherical shape due to tight folding of polypeptide chains. -Soluble -Roles in Metabolism or Synthesis of large molecules
Structure and role of Antibodies	-Involved in Immune response -Two light (short) polypeptide chains and two heavy (long) polypeptide chains -Have variable regions
Structural Proteins	-Physically Strong -Consist of long polypeptide chains that lie parallel to each other w/ crosslinks between them - Include Keratin (In hair and nails) and Collagen (connective tissue)
Lock and Key Model Vs Induced Fit Model	L+k - Active site shape is rigid, only exact complementary substrates can bind to form Enzyme-Substrate complexes I F - Active site changes shape, substrate binds to act site, active site changes shape so the substrate fit exactly forming Enzyme-substrate complex
Affect of Substrate concentration on enzyme activity	- Increase substrate concentration = -Increase chance of successful collisions -Increase chance of forming an enzyme substrate complex -Increase rate of reaction -Continues until all enzymes are satisfied
Affect of enzyme concentration on enzyme activity	Increase enzyme concentration = -increase chance of successful collisions -increase chance of forming an Enzyme- substrate complex -increase R of R -this continues until all substrates are used up + max. R of R
Affect of temp on enzyme	Temp increases = -increase R of R -Kinetic energy increases -Molecules move faster -Increase chance of successful collisions and Enzyme-substrate complex -caries until optimum After Optimum = -Decrease R of R -Bonds in tertiary structure break -Lose Active site -enzyme denatured
Affect of pH on enzyme activity	Change in pH away from optimum = -Bonds in tertiary structure break -Lose active site -Denatured enzyme - No Enzyme-Substrate complex
Competitive VS non-competitive inhibitors	- C = - A substance with a similar shape to substrate w/ complementary shape to enzyme active shape -Binds to active site, block it, prevent ES complexes forming N-C = - Substance that binds to another site on the enzyme other then the active site, changing the active site shape -

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