Università degli Studi di Urbino Carlo Bo / Portale Web di Ateneo


Expression, purification and characterization of recombinant proteins produced in E. coli
Espressione, purificazione e caratterizzazione di proteine ricombinanti prodotte in E. coli

A.Y. Credits
2016/2017 8
Lecturer Email Office hours for students
Rita Crinelli by appointment calling the number 0722-305220 o via e-mail
Teaching in foreign languages
Course with optional materials in a foreign language English
This course is entirely taught in Italian. Study materials can be provided in the foreign language and the final exam can be taken in the foreign language.

Assigned to the Degree Course

Biotechnology (L-2)
Date Time Classroom / Location

Learning Objectives

The course introduces students to the processes of recombinant protein production in Escherichia coli. In particular, the purpose of the course is to let the students to acquire the theoretical principles, and the practical skills necessary to express, purify and characterize recombinant products. Recombinant proteins are biotechnology products widely used as laboratory reagents as well as diagnostics and therapeutics in biomedicine. Thus, the knowledge of the processes and the mastery of the techniques used for their production are of fundamental importance for a Biotechnologist.


The following topics will be addressed as outlined below

1. Electrophoretic techniques for protein analysis
1.1 Ionic properties of aminoacids
1.2 Physical aspects of the electrophoretic separation
1.3 Polyacrilamide gels
1.5 Discontinuous gel system
1.6 Gel staining methods
1.7 Western immunoblotting
1.8 Native PAGE
1.9 Electrophoretic mobility shift assay (EMSA)
2. Spectrophotometric protein assays
2.1 Absorbance at 280 nm
2.2 Bradford method
2.3 Lowry method
3. The Escherichia coli expression system
3.1 Advantages of recombinant protein expression
3.2 Features of the E. coli expression system
3.3 Expression vectors
3.3.1 Multicloning site and codon usage
3.3.2 Replication origin and plasmid copy number
3.3.3 Strong and regulatable promoters (lac, trp, PL,T7)
3.3.4 Antibiotic resistance genes and recessive markers
3.3.5 Ribosome Binding Site
4. Strategies to prevent recombinant protein degradation in vivo
4.1 Bacterial proteases and their cellular localization
4.2 Manipulation of culture conditions
4.3 Host engineering
4.4 Product engineering
5. Strategies to prevent the formation of inclusion bodies
5.1 Protein folding and inclusion body formation
5.2 Manipulation of culture conditions
5.3 Host engineering
5.3.1 "Oxidant" strains
5.3.2 Co-expression with molecular chaperones
5.4 Product engineering
5.4.1 Secretion into the periplasm
5.4.2 Fusion proteins (MBP, GST, SUMO)
5.5 Fusion tags
6. Bacterial lysate preparation and initial fractionation
6.1 Cryoconservation of the biomass
6.2 Cell disruption
6.3 Composition of the protein extraction buffer
7. Recovery of bioactive recombinant proteins from inclusion bodies
7.1 Protein solubilization
7.2 Refolding in vitro
8. Designing a purification scheme
8.1 Lysate clarification
8.2 Key steps in a purification protocol
8.3 Selection of a specific assay for the protein of interest
8.4 Selection and logical combination of purification techniques
8.5 % yield and purification enhancement
9. Purification of fusion proteins by affinity chromatography
9.1 The matrix
9.2 The ligand
9.3 The spacer arm
9.4 Elution techniques
10. Characterization of the protein product
10.1 Bacterial endotoxins: structure and clinical implications
10.2 Techniques for the detection of endotoxin contaminants
10.2.1 Rabbit pyrogen test
10.2.2 Limulus Amoebocyte Lysate (LAL) test (gel clot, chromogenic, turbidimetric, recombinant)
10.2.3 Test of cytokine release
10.3 Methods for endotoxin removal
10.4 Mono- and polyclonal antibodies
10.5 Immunization techniques
10.6 Immunoglobulin purification methods
10.7 ELISA
10.7.1 direct ELISA
10.7.2 indirect ELISA
10.7.3 competitive ELISA
11. Expression and purification of a recombinant protein: from the theoretical principles to the laboratory practice
11.1 Preparation of the stock solutions for SDS-PAGE
11.2 Setting up of a protein standard curve for the Bradford assay
11.3 Preparation of the culture medium for bacterial growth, buffers for bacterial lysis and extraction of soluble and insoluble proteins
11.4 Bacterial inoculation, growth, induction of recombinant protein expression
11.5 SDS-PAGE analysis of recombinant protein expression
11.6 Cell disruption, protein extraction and initial fractionation
11.7 SDS-PAGE of the soluble and insoluble fraction
11.8 Protein purification by affinity chromatography
11.9 SDS-PAGE analysis of the chromatographic fractions
11.10 Cleavage of the fusion partner
11.11 SDS-PAGE and Western Immunoblot analysis of the recombinant protein
11.12 LAL test, gel clot
11.13Titration of an antibody against a recombinant antigen by indirect ELISA

Bridging Courses


Learning Achievements (Dublin Descriptors)

Students are expected to acquire and understand the notions concerning the most widely used laboratory techniques and experimental strategies to express, purify and characterize recombinant proteins; to be able to understand and perform an experimental protocol taking advantage both of the theoretical bases and of the laboratory instrumentation; to critically analyze results obtained, identify problems and find solutions; to report and comment on the results obtained; to autonomously develop a protocol for the expression and purification of a recombinant protein.

Teaching Material

The teaching material prepared by the lecturer in addition to recommended textbooks (such as for instance slides, lecture notes, exercises, bibliography) and communications from the lecturer specific to the course can be found inside the Moodle platform › blended.uniurb.it

Supporting Activities

20h seminars - Dr. Sabrina Dominici

Teaching, Attendance, Course Books and Assessment


Lectures and laboratory lessons. The schedule will be established at the beginning of the course


Students must attend at least 2/3 of the lessons.

Course books

B.R. Glick, J.J. Pasternak, Biotecnologia Molecolare, Principi e Applicazioni del DNA Ricombinante, Zanichelli.
K. Wilson, J. Walzer, Metodologia Biochimica, le Bioscienze e le Biotecnologie in Laboratorio, Raffaello Cortina Editore.
M. C. Bonaccorsi di Patti, R. Contestabile, M. L. Di Salvo, METODOLOGIE BIOCHIMICHE - Principi e tecniche per l'espressione, la purificazione e la caratterizzazione delle proteine. Casa Editrice Ambrosiana.
R. K. Scopes, Protein purification, principles and practice, Springer-Verlag.

other material (slides, protocols and reviews) will be provided during the course


Oral examination


The student can request to sit the final exam in English with an alternative bibliography.

« back Last update: 31/08/2016


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