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Derived from the Greek word Proteios, which provides structure in membranes, build cartilage and connective tissue
Proteins
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Building blocks of proteins are linear polymers built of monomer units called
amino acids
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Amino Acids contain
- * Amino group
- Hydrogen group
- Carboxylate group
- Alpha carbon
- R group
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All amino acids in our body are the
L-isomer
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The R groups in this class of amino acids are hydrophobic
Non-polar, Aliphatic R groups
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They have aromatic side chains, are relatively nonpolar
Aromatic R groups
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The R groups of these amino acids are more soluble in water or more hydrophilic
Polar, uncharged R groups
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The amino acids in which the R groups have significant charge at pH
Positively charged (basic)
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Amino acids having a net negative charge; Each of which has a second carboxyl group
Negatively charged (Acidic) group
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10 essential amino acids, which our body can synthesize
- P-Phenylalanine
- V- Valine
- T-Threonine
- T- Tryptophan
- I-Isoleucine
- M-Methionine
- H- Histidine
- A-Arginine
- L-Leucine
- L-Lysine
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Foods contain all the essential amino acids in the proper amounts
Complete protein
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Are obtained from vegetables is low
Incomplete protein
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Dipolar ion a.k.a ____, explain.
Zwitterion, Has a net charge of 0 and has a positive and negative group. They are able to accept and donate protons and are often called "ampholytes"
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Common amino acids are
Standard amino acids
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Are amino acids that are chemically modified
Nonstandard amino acids
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When writing and naming a peptide, what are important things to remeber:
- 1. Always start with the N terminal to C terminal
- 2. Change the last name to yl(except sa last amino acid) ex. Glycine + alanine= Glycylalanine
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An amino acid polymer of short chain length
Peptide
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Polypeptide
Containing up to 50 amino acids
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Protein
An amino acid polymer that contains up to more than 50 amino acids
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A chemical effect that makes our skin white, also an intracellular reducing agent
Glutathione
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Anti-diuretic
Di maka ihi
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Produced by the cleavage of polypeptide precursors within different specialized cells in the hypothalamus
- 1.)Oxytocin- stimulates contraction of uterine muscles during childbirth & the ejection of mammary milk during lactation
- 2.) Vasopressin a.k.a antidiuretic- is secreted in response to low blood pressure or a high blood sodium concentration
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Met-enkephalin and leu-enkephalin (pentapeptides)
Belong to a group called "opiod peptides" found in nervous tissue cells, are molecules that relieve pain and produce pleasant sensations
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A peptide produced by specialized cells in the heart and the nervous system, they stimulate the perception of pain and is opposed by opioid peptides
Atrial natrieuritic factors (substance P and bradykinin)
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Why we have different protein structures?
Since they have different jobs, ex. Hemoglobin is a type of protein that transports oxygen, if they cannot fulfill that role then people would die.
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A protein's amino acid sequence that determines its overall shape, function and properties; Sequence of amino acids linked by peptide bonds
- Primary structure
- :The change of only one amino acid can alter a protein's biological properties and the protein become unfunctional ex. Sickle cell anemia
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What is sickle-cell anemia?
A mutation of single amino acid, are unable to pass through small capillaries of the circulatory system that results to organ damage and death. Is also inheritable
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The polypeptide chain is reacted with 1-fluoro-2,4- dinitrobenzne (DNFB)
Sanger's method
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Used to identify C-terminal residue
Carboxypeptidase
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Trypsin
Cleaves lys and Arg- AA1
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Chymotrypsin
Cleaves Phe,Tyr, Trp -AA1
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Pepsin
Cleaves Phe,trp,tyr,asp,glu,ile
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DNFB
Cleaves the N-terminal
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The chain of covalently linked amino acids, folds into regularly repeating structures that resemble designs in a tapestry
Secondary strucutre
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Because many H-bonds occur within the polypeptide, the chain is pulled into a tight coil that looks like a spring or telephone cord
a-helix
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Is used to break disulfide bonds
Performic acid
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Formed when two or more polypeptide chain segments line up side by side; each individual segment is referred to as B-strand (fully extended)
B pleated sheet
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2 types of B- pleated sheet
- 1.)Parallel- N terminal are head to head
- 2.) Antiparallel- N terminal & C terminal are head to head (more stable)
- ex. Silk fibroin
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Most uncommon type of structures in secondary structure
Triple helix ex. collagen, vitamin C is important in maintaining collagen
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Are globular structures of proteins that have three dimensional. The polypeptide chain w/ its regions of secondary structure a-helix and B-pleated sheet.
Tertiary structure
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Different R groups
- Peptide bonds- primary structure
- Peptide & H bonds- secondary structure
- H bonds between R- tertiary
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Types of interaction to stabilize tertiary structure
- 1.) Van der waals- hydrophobic interaction
- 2.) Hydrogen bonds- hydrophilic interaction
- 3.) Ionic bonds- oppositively charged
- 4.) Covalent bonds- link between sulphur atoms of 2 cys AA
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A protein found in striated muscles which its main function is to supply oxygen to cells
Myogoblin
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consists of 2 identical a-subunits and 2 identical R subunits; 4 peptides are bond to one another
Quaternary structure
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Fibrous protein
are insoluble in water, makes up the tough fibers of skin,cartilage nails and collagen
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Globular proteins
water soluble, nearly spherical in shape; functions in the cells as enzymes, hormones and antibodies
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Unfolding of the native conformation; a change that disrupts the interactions between R groups
Denaturation of Proteins
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Factors that denature a protein
- 1.) Temperature- When temp. increases, hydrogen bonds are disrupted and coagulation occurs as molecules unfold
- 2.) pH- If mubo ang pH cations and if taas anion; positively (cat) and negatively (an) charged R groups on the surface interact w/ ions and molecules
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Organic Solvents
denature proteins by disrupting hydrogen bonds within the protein
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Detergents
detergents interact w/ proteins, they disrupt hydrophobic interactions causing the protein chain to unfold
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Heavy metals
this interferes w/ the salt bridges formed between amino acid R groups of the protein chain
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Agitation
Caused by mechanical stress that denatures a protein ex. Whipping of cream and beating of eggs
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Explain mad cow's disease
A disease of cattle in which the peptide chain folds into a B-pleated sheet that has disastrous effects on the brain and spinal cord
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Immunoglobulins explain
These are proteins that defend our body, it's response is directed to only one organism, once the immune system responded it is protected from that same organism.
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Types of Immunoglobulin
- 1.)Immunoglobulin G (IgG)- protects the fetus against most bacterial and viral infections that it might encounter before birth.
- 2.) Immunoglobulin M (IgM)- found in blood, first antibody to fight infections
- 3.)Immunoglobulin A (IgA)- responsible for protecting the body surfaces; is also found in mother's milk
- 4.)Immunoglobulin D (IgD)- found in large quantities in the blood of people suffering from allergies.
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