Introduction toStudying Proteins

What is going on?

?

Study QuestionsDescribe the structure of proteins, including the significance of amino acid

R-groups and their impact on the three-dimensional structure of proteins.Explain the steps of transcription and translation in protein synthesis.Discuss the role of naturally occurring proteins and recombinant proteins in

biotechnology.Differentiate proteins that function as part of structure, as antibodies, and as

enzymes.Describe the structure of antibodies and explain the relationship between

antibodies and antigens.Discriminate among the classes of enzymes and discuss the effect of

reaction conditions on enzyme activity.Summarize polyacrylamide gel electrophoresis and identify its usefulness for

studying proteins.

5.1 The Structure and Function of Proteins

• Virtually all biotechnology products have something to do with proteins.

• Protein has a three-dimensional structure.

Protein Molecule Structure

• Polymers composed of amino acids• Twenty different kinds of amino acids are found in protein• Most proteins contain tens of hundreds of amino acidsFunction of Structural

ProteinsFor an HIV particle to recognize, attach, and infect a T-helper cell, the gp210 structure must be a precise shape and must exactly match its human cell membrane receptors

Function of Antibody ProteinsRecognize and bind foreign proteins or other molecules (antigens) for removal from the body

Protein Structure and Function Relationship

Secondary Structure

Protein Structure is Complex Primary structure – the order and type of amino acids

found in a polypeptide chain Secondary structure – the structure of a protein (alpha

helix and beta sheets) that results from hydrogen bonding Tertiary structure – the structure of a protein that results

from several interactions, the presence of charged or uncharged “R” groups, and hydrogen bonding

Quaternary structure – the structure of a protein resulting from the association of two or more polypeptide chains

Studying ProteinsWhat and how?

5.2 The Production of Protein

Until recently, proteins could only be made in cells.Now small polypeptide chains can be synthesized in the laboratory.

Overview of Protein Synthesis

Protein synthesis occurs continuously throughout a cell’s lifeEukaryote and prokaryote – protein synthesis is similar

Protein Synthesis in a Eukaryotic Cell. In a eukaryotic cell, DNA is located within chromosomes in the nucleus. The mRNA transcripts carry the DNA code out to the ribosomes, which translate the code into a strand of amino acids.

Genetic code must be rewritten onto a messenger molecule

First Step:

Protein synthesis is a two-step process:

Transcription and Translation

mRNA nucleotide code is rendered into a sequence of amino acids

Second Step:

The Importance of Proteins in Biotech R&DThe ability to synthesize and modify peptides or proteins is crucial to the production of virtually every biotechnology product.

Enzymes: Protein CatalystsEnzymes are proteins that act as catalystsEnzymes are involved in virtually every reaction in a cellMany companies have focused on producing enzymes for saleEnzymes and Their SubstratesThe molecules upon which enzymes act are called substrates

Factors That Affect Enzyme Activity

Applications of Protein Analysis1. Protein profile of cells

and tissues2. A protein’s structure

can help explain its function

3. Chemical processes in cells

4. Evolution and taxonomic relationships

Advanced Protein StudiesA single gene can encode for as many as 50 different protein forms.X-Ray Crystallography

Protein (x-ray) crystallography visualizes the positions of atoms in a molecule based on x-ray wave diffraction, and the constructive and destructive interference that results off the atoms in the sample.

ELISAELISA is one of the most frequently used assays in protein manufacturing.Western BlotsRunning samples on acrylamide gels can provide a great deal of information about the proteins in a sample.

Antibody Proteins

Other Advances and Applications of Biotechnology• Pharmacogenetics• Environmental biotechnology• BiodefensePharmacogenetics – Personalized MedicinesSince every person’s DNA is different, doctors will be able to design and modify drugs to better meet individual needs.

Environmental BiotechThis is a vast field with many applications for monitoring and correcting the health of entire species, populations, communities, and ecosystems.

Biodefense: Protection Against BioterrorismBiodefense is the term for all of the methods used to protect people from exposure to biological agents.