Amino Acids
- Building blocks of proteins
- Essential and non-essential
- 20 central to human body
R-groups of amino acids
Hydrophobic
Hydrophilic
Charged
Special
Components of Amino Acids
Amino Group
Carboxylic Group
Hydrogen Atom
Central carbon atom is chiral
R-groups
vary with each amino acid
At physiological pH, the charged groups of amino acids are ______
Water soluble
Hydrophobic Amino Acids
Glycine
Alanine
Valine
Leucine
Isoleucine
Phenylalanine
Trytophan
Water-hating that want to be folded in a protein or covered by another part of a protein or lipid hidden from water
Hydrophilic Amino Acids
Serine
Threonine
Asparagine
Glutamine
Water-loving with partial charges, prefer to be at the surface of proteins to interact with water
Charged Amino Acids
Tyrosine
Aspartic Acid
Glutamic Acid
Lysine
Arginine
Positively or negatively charged that want to be at the surface of folded proteins or with other charged atoms/molecules
Special Amino Acids
Proline
Cysteine
Methionine
Histidine
What is Proline special?
Structure allows for the formation of the "hairpin" beta-turn from an amino bond
What is Cysteine special?
Sulfhydryl bonds may lose one hydrogen atom to become cystine.
pH increases results in an loss of a H
Peptide Bonds
- Bond amino acids
- Link carboxyl group of one amino acid to amino group of amino group
- R-grups predict the folding patterns , binding sites, and other interactions
- Results in loss of water
Example of a Peptide Bond
Protein Structures
Primary
Secondary
Tertiary
Quaternary
Primary Protein Structure
- Amino acids linked by peptide bonds
- 1�
- Beads on a string
Secondary Protein Structure
- alpha-helix (tightly packed core)
- beta-strand (maximizes H-bonding, antiparallel or parallel)
- with H-bonds
- 1� to 2� structure
Tertiary Protein Structure
- 2� structures interact to from 3�
- 2� fold hydrophobic and hydrophilic for hydrogen and ionic bonding
- R-groups interact
Quaternary Structure
- 3� subunits interast
- Hemoglobin (example)
Categories of proteins
Enzymes
Structural proteins
Motor proteins
transport/channel proteins
Enzymes
- End in -ase
lactate dehydrogenase (LD)
- 6-stranded
- Tertiary structure
- Brain, RBC, kidney, liver, lung, heart, spleen
- last step in glycolysis
Adrenaline
Structural Protein
Collagen
- Triple helix w/ H-bonding
- Osteogenesis Imperfecta (OI): disease that affects the collagen by destabilizing and altering the triple helix
- Scurvy: Deficiency in Vitamin C that stabilizes collagen
- GAG
What is Histidine special?
Precursor for Histamine
Motor Protein
Myosin
Carbohydrates
- end in -ose
- Fischer Projection of Ring closure
- Examples: Fructose and Glucose
- Triose, Tetrose, Pentose, Hexose, Heptose
Biochemical roles of Carbohydrates
- Energy Source: Carb metabolism
- Structural: Nucleic acids / cell walls
- Binding: Points of binding
- Signaling: Recognition of specific sugars
Monosccharides
- Single sugar residuals
Examples
- Triose glyceraldehyde
- Pentose ribose
- Hexosos Fructose, Glucose, and Galactose
Diasaccharides
Examples
- Lactose (in milk)
- Trehalose (in sunflower seeds, shrimp, & mushrooms)
- Maltose (in barley)
- Sucrose (table sugar)
Polysaccharides
Glucose polymer: Glycogen (stored in the liver)
Cellulose (cell wall)
Lactose Intolerance
- Lack enzyme (lactase) to break down disaccharides
- Mini-Chromosome Maintenance (MCM6) turns off the LCT gene that makes lactase
- Not the same as milk allergy
Glycoproteins
- Mainly Proteins with small percent of Carbohydrates
Glycosaminoglycans (GAGs)
- Contain repeating disaccharide chains to make a extracellular matrix
- Glucosamine, Galactosamine
Most common
- Heparin (NHSC3-)
- Chondroitin (NHCOCH3)
- Hyaluronic acid
Combined with proteins = proteoglycans
Proteoglycans
Polysaccharides with a small percent (<10%) of protein
Heparin Sulfate
GAG
- Extracellular on epithelial cells to prevent blotting/binding
Hyaluronic Acid
GAG
- Synovial fluid, vitreous humor, loose connective tissue, and cartilage
Keratan Sulfates
GAG
- Found in corneas and loose connective tissue
Dematan Sulfates
GAG
- Found in skin, blood vessels, heart valves
Lipids
Key component of biological membrane
- Energy storage and transport
- Cellular binding and recognition
- Signaling
- Digestion
- Metabloism
?-linolenic acid (ALA)
- Essential Fatty Acid
18 carbons with C=C at third carbon (double bond at 3rd carbon = omega 3 acid)
Linoleum Acid (LA)
- Essential Fatty Acid
18 carbons with C=C at sixth carbon (double bond at 6th carbon = omega 6 acid)
Important Fatty Acids
- Arachidonic Acid (AA) (from linolenic acid): biological functions
- Eicosapentaneoic Acid (EPA): precursor for prostaglandins
- Docosahexaenoic Acid (DHA): higher levels in the brain
Omega-6
pro-inflammatory and excessive intake may also increase risk of heart attacks, strokes, some cancers, and depression
Saturated Fatty Acids
- All single Bonds
- Hydro-carbon chain
- Non-water soluble
Palmitate acid, Stearate acid, Arachidate acid
(all of only C-C bond)
Unsaturated Fatty Acids
- At least one C=C bond
- Can becomes saturated with 2x hydrogenated
- Can be Cis or Trans
Oleic acid, (cis, 9)
Elaidic acid (trans, 9)
Linoleic acid (cis, 9 and 12)
Higher saturation =
Higher meting point
Lower saturation =
Lower melting point
Humans cannot produce_____
C=C bonds at omega-3 and omega-6. Must obtain from vegetable oils
Ester
Alcohol and Carboxylic acid
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