Download Proteins

생물공학 기초 1 : 생화학
Molecular Components of Cells
 Chemical composition
 C, H, N, O and small amount of other elements
 Molecular building blocks




Lipids
Carbohydrates
Proteins
Nucleic acid
• DNA (deoxyribonucleic acid)
• RNA (ribonucleic acid)
Subunits of Biological Molecules
Class of Molecules Examples
Repeating Unit
Lipid
Fats, oils
-
Carbohydrate
Sugars, starch,
cellulose
Monosaccharide
Nucleic acid
DNA, RNA
Nucleotide
Proteins
Enzymes,
Antibody
Amino acids
Lipids
 Hydrophobic fats, oils (liquid fats), and cholesterol etc.
 High energy C-H, C-C bonds  good energy storage
 Fats : glycerol + fatty acids
Triglyceride
Energy storage
 Lipid : ester bond (-COO-)
 나이 들면 살찌는/배 나오는 이유?
 미생물도 에너지 저장 : PHB polyester
* PHB : poly hydroxy butyrate
* biodegradable
* polyester fiber (예 :TPA+MA) 와의 차이?
 FAME(fatty acid methyl ester) : biodiesel
Carbohydrates
 C:H:O = 1:2:1
 Simple sugars (monosaccharide)
 Glucoes, fructose, galactose
 Disaccharide
 Simple sugars linked by glycosidic bond
 Sucrose (glucose+fructose), Lactose (glucose+galactose),
Maltose (aglucose +bglucose)
Proteins
 Roles of proteins
 Most of the cellular functions
• Enzymes : chemical reactions
• Receptors : signal transduction
• Antibody : recognition of foreign molecules and trigger
immune responses
• Transporters : e.g. hemoglobin for oxygen
• Structural proteins : keratin (hair and nails), actin and myosin
(muscle)
 Diversity of organism
• Diversity of organization of proteins within an organism
Proteins
 Amino acids
 Building blocks of proteins
 Hydrophilic backbone + 20
side chains
 Polypeptide
 Amino acid chains linked by
peptide bond
 Tree-dimensional structure
 Determines protein function
 Determined by amino acid
sequence
Amino Acids and Primary Structure
 Amino acids
 Amino group
 Carboxyl group
 R group; 20 Side
chains
 Peptide bond
 Between NH2 and
COOH
 Polypeptide
 A chain of amino acids
 N terminus and C
terminus
Amino Acids
Primary and Secondary Structure
 Primary structure
 _______________________________________
 Secondary structure
 Core elements of protein architecture
 Neutralization of partial charges of the peptide
backbone by hydrogen bonding
 Local folding of polypeptide chain
• _____________ : 60% of the polypeptide chain
• Random coils and U-shaped turn
a-Helix
 Hydrogen bond between
carbony O (n) and amid H
(n+4)
 Directionality on the helix :
The same orientation of H
bond donor
 Side chains point
_______
 Determine hydrophobic or
hydrophilic quality
b-Sheet
 Laterally packed b
strands of 5 to 8
residue
 Hydrogen bonding
between b strands 
b sheet, pleated sheet
 Parallel or antiparallel
Tertiary Structure
 Tertiary structure
 Overall folding of a polypeptide chain
 Stabilization
• weak interaction
– Hydrophobic interaction between nonpolar side chains
– Hydrogen bond between polar side chains and peptide bonds
• Disulfide bond formation
Quaternary Structure
 Association of multiple polypeptide chains
 Lambda repressor : dimer
 E. coli RNA polymerase : Five polypeptide chains
Disruption of Protein Structure
 Factors disrupting protein sturcture
 Heat, extreme pH, organic solvent, detergent
 Denaturation
 Complete unfolding of amino acid chain
 Sometimes irreversible : e.g. boiled egg
 Melting temperature (Tm)
• Denaturation temperature for a given protein
• Depending on protein structure
– Proteins from organisms living in thermal vents
Examples of Protein Structure and
Function
 Keratin
 Structural protein for hair, wool,
feathers, nails, scales, hooves,
horns, skin
 Very strong and water insoluble
• Hydrophobic alpha helices
– Long a-helix with hydrophobic
amino acids (A, I, V, M, F)
– Forming fibers by hydrophobic
interactions
• Disulfide bonds
– The more S-S bonds the
harder the structure
– Permanent wave
» Reducing of disulfide
bond  Generation of
new disulfide bond
Protein Engineering
 Manipulation of protein’s amino acid sequence
to change its function or properties
 Chemical manufacturing
 Develop enzymes more suitable for industrial
applications
 Increasing enzyme stability
• e.g. bacteriophage lysozyme: introduce S-S bond to
increase heat resistance
• Proteases in detergent
Nucleic acids
 Nucleotides
 Building blocks of nucleic acids
 (deoxy)ribose + phosphate group +
4 bases
 Bases: adenine (A), guanine (G),
cytosine (C), thymine (T)
 Terminology
 Base
 Nucleoside :
 Nucleotide :
Primary Structure : Nucleotides
Base
Nucleoside
Nucleotide
Adenine
Adenosine
Adenylate
Guanine
Guanosine
Guanylate
Cytosine
Cytidine
Cytidylate
Thymine (D)
Thymidine
Thymidylate
Uracil (R)
Uridine
Uridylate
Purine
Pyrimidine
H
2’-Deoxyribose
RNA
DNA
Nucleotide Chains
 Base pairing
 C=G, T=A : hydrogen
bonding
 Complementary base pairs
 Antipararallel strand in
DNA molecule
Chromosome
 Tightly packed complex of DNA and _____ proteins
DNA Replication
 Synthesis of a complementary strand using the other strand as a
template
 _____________
Expression of Genetic Information
Replication
DNA
Transcription
mRNA
Translation
Protein




유전자 조작 ?
유전자 변이 – 질병으로 연결
Gene structure vs function
---