Final - Schneebeli Flashcards
Peptide
A chain of amino acids (typically less than 40-50 amino acids)
Protein
Longer amino acid chain with secondary structure (longer than 40-50 amino acids)
From spheres to chemical structures
Semaglutide (Ozempic)
-Big vs small molecule drug
PEPTIDE BOND
Semaglutide (Ozempic)
Synthetic peptide
31 Amino acids (peptide, not protein)
Weight loss drug
All antibodies are
Proteins
Peptide drugs can be produced with
Solid-phase synthesis
Key challenge with nonenzymatic peptide synthesis
Coupling yields need to be extremely high, for a long linear synthesis
-Yields for consecutive reactions need to be multiplied
Q: What would the overall yield be when synthesizing a linear peptide with 31 amino acid residues, and a yield of 90% for each coupling step?
0.038
-3.8% yield - this would only give 3.8% yield = VERY LOW = NOT GOOD
Proteins depend on the length of the Peptide chain
Protein is any alpha amino acid polymer with a specific sequence that is greater than 40 amino acids in size
Example of a protein
Insulin
51 AAs
Need to count both chains
Compounding of _ is NOT allowed
Biologics
-Biological products are not eligible for the exemptions for compounded drugs under federal law
Biologics are very fragile - dangerous to do too much with them
Protein drugs
Over 1,000 amino acids in length
Cannot be synthesized chemically
Highly complex and fragile drugs
How are protein drugs produced
Produced by biosynthesis
Much more complex than small molecule drugs
100 to 1.00 liters
(mobile) pilot plant
probes for
-pH
-Dissolved O2
-Temperature
pressure
biomass
carbon source
Ribosomal synthesis to post-translational modification
All controlled by the ribosome
-Takes messenger RNA and converts and uses as a template for proteins
know post-translational modifications
Post-translational modifications
Disulfide bond
Hydroxylation
Ubiquination
Lipidation
SUMOylation
Phosphorylation
Acetylation
Methylation
Glycosylation
Comparison of different expression systems
Bacteria
-no glycosylation, endotoxins
Yeasts
-Glycosylation is limited, or proteins are hyperglycosylated
Insect cells
-Extensive glycosylation, no sialytransferase, insect specific glycans
Mammalian cells
CHO etc (expensive susceptible to contamination with human pathogens or oncogenes)
for antibodies, people usually go with this
Transgenic animals
-Expensive, susceptible to contamination with animal pathogens
Transgenic plants
-Inexpensive, no contamination with animal pathogens, glycosylation
Posttranslational Modifications (PTMs) - Primary Difference Between Biosimilars
Target DNA, express it, different PTMs
-Similar, but not the same (different sugars)
-Might get the same protein sequence, but never 100% the same (NOT a generic)
Even a small difference in _ can lead to serious issues
Glycosylation
Ex. - Immune response
Conditions that can lead to protein degradation
High temp
Freeze-thaw
Agitation
Low pH
High pH
Forced deamidation
Oxidation
Photostability
Agitation can lead to
Increased contact with surfaces, which in turn leads to aggregation
DO NOT SHAKE
Why not to freeze biologics
Ice crystals form = more concentration = more aggregation
T/F: Aggregation can happen a while after the aggregate forming event occurs
True
Happens much later, and very rapidly
Native state
Folded state
Drug we want
Smaller surface area
Unfolded state
Enhances aggregation
No longer has function
Can lead to immune response
Undesirable
LARGER surface area
Which Gibbs is preferred, higher or lower?
LOWER - native
In preferential exclusion: Excipients are _ from protein surface
Repelled
More dimer formation leads to
More aggregation
Why do we not compound biologics
Unpredictable; dimer formation happens at different concentrations for different proteins = leads to aggregation
Nature can store proteins for a very long time in
Sugar glasses (Trehalose)
-Biomimicry (stabilize)
Levemir
Long lasting insulin
Hydrophobic tail attached to insulin binds to albumin which extends the half-life
T1/2: 5-7hrs
98% of the drug is bound to albumin
Semaglutide
LONG hydrophobic tail
Also binds to albumin
General strategy
t1/2: 7 days
