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8/3/2019 CENG 109 Class 5
1/22
CENG 109 class 5
Bioprocess Engineering
8/3/2019 CENG 109 Class 5
2/22
Class announcement Class project
Team forming situation Schedule for library training will be posted on
class web site. Attendance is mandatory
Make-up class in early October (to
replacing missing class on October 24)
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Outline for this class
The definition and scope of bioprocess
engineering
The technical challenges for bioprocess
engineers
Case studies of early biotechnology products-Insulin
-tPA
The economic impacts of bioprocessengineering
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Science and the application of
science are linked as the fruitis to the tree
Louis Pasteur
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Definition of
Bioprocess Engineering
Discovery in
Basic Science
Bioprocess Engineering PracticalProducts,
Processes
or Systems
Market Force
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What is bioprocess engineering about?
A bioprocess includes an
upstream process and adownstream process
Upstream: product production
in cell cultures/fermentations
Downstream: isolation of
product and its formulation
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What is bioprocess engineering? the design and construction of a
bioreactors (fermentation tanks) to growcells
the design and utilization of different
equipments to isolate the products
traditional engineering approaches for
scaling up and minimizing costs
the design and construction of living
organisms to optimize product production
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Technical Challenges
Number of protein products:from almost none to many
Complexity of protein products: High Liability of protein products: High
Purity requirement: High Scale of production and product
pricing: Highly variable
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Unit value and production quantities
of early biotech products
0.24840,000Erythropoietin
8.723,000Tissue plasminogen
activator (tPA)
5.735,000Growth Hormone
530375Human insulin
20,00010Human serum albumin
Amount of Productfor $200M in sales,
kg
Approx. selling price$/g
Product
Source: National Academy of Sciences, Committee on Bioprocess Engineering (1992)
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Insulin case studyThe first production process of human insulin involved
separate expression of A and B chains.
To stablize each chain, each chain is fused to a largerprotein to form insoluble granules. The fusion proteins are
subsequently removed and the two chains recombined .
Fi ure extracted from Biose arations En ineerin : Princi les Practice and Economics b Ladish
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Upstream process made more
efficient by mimicking nature
This figure
Illustrates
insulin synthesisin pancreas
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The proinsulin method is adopted
to improve production efficiency
Fi ure extracted from Biose arations En ineerin : Princi les Practice and Economics b Ladish
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The proinsulin method is adopted
to improve production efficiency
The one-chain proinsulinmethod has been adopted
to improve the yield of
correctly folded proteins.
What kinds of expertise
are required to achievethis improvement?
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Isolation of human insulin requires
27 stepsWhy multiple steps are
needed?
Principles of orthogonalityProduct is the minority, to
be selected among many
different biomolecules and
cell debris
Similarity bewteen product
and
JunksRegulations require high
product purity (contaminants
below parts per millionrange)
Fi ure extracted from Biose arations En ineerin : Princi les Practice and Economics b Ladish
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Product yield loss amplified by the
number of purification steps
Overall Product Yield = (1- L%)n x 100%
Lets calculate the yield for a 10-step processwith a step loss of 5%
The early insulin production process has a
overall yield of 29%=> Lower product yield is translated to higher
manufacturing cost
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tPA case study Tissue plasminogen
activator can dissolveblood clots --- is atherapeutic for treatingheart attacks and strokes
Sold as Activase, its
sale accounted for 30%of total sales ofGENENTECH, andabout 1/3 of theworldwide sales in bloodclot dissolvingtherapeutics in 1995
Unlike insulin, it isregulated as a biologic,not a drug
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Production of tPA: a unique opportunity for
the application of recombinant technology
50,000L of blood required to extract single
dose of tPA (~100mg) not practical
Recombinant technology provides afeasible approach
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4NoneGlycosylation
sites
123Disulphide
bonds
66,000 Da5,600 DaSize
tPAInsulin
But tPA is much more
complicated than insulin
.and achieving correct protein folding is more difficult
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Molecular arrangement of tPA
Lets count the no. of disulphide bridges (solid bars), potential cleavage sites
(arrows), glycosylation sites (zigzag lines) and short peptide bridge (dotted line)
Figure extracted from Bioseparations Engineering: Principles, Practice and Economics by Ladish
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Upstream process can be made
more efficient by mimicking nature
YesNoSecrete products tomedium?
ExtensiveNonePosttranslationalmodification?
YesNoRemove introns?
HighLowMaintenance cost
LowHighReplication rate
Mammalian Cells
(e.g. Chinese
Hamster Ovary Cells)
Bacteria
(E.Coli)
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Mammalian cell culture creates
new downstream challenges
Fear of transfer of infectious agents
Fear of genetic materials from cell linescausing cancer
Purification process must be able to removecells, virus and DNA
Analytical assays must be able to detectvery low level of cells, virus and DNA
Lead to advance in downstream processingunits, particularly membrane andchromatography applications
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Get it fast and get it right
the first time
Bioprocess cost is secondary to being firstto market
But cost of product is important in
subsequent competition with rival products For biologic, the license provision requires
not just the product, but also the
manufacturing process/facility be approved
A huge cost barrier exists to implement
process changes after license is granted
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