Pitt BIOSC 1000 - Protein Purification (9 pages)

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BIOSC 1000 Lecture 5 Outline of Last Lecture 1 Review of Peptides 2 Properties of the Peptide Bond 3 Secondary Structure of Proteins 4 Tertiary Structure of Proteins 5 Quaternary Structure of Proteins 6 The Biological Protein Folding Problem Outline of Current Lecture 1 Protein Structure Review 2 Protein Purification Current Lecture 1 Protein Structure Review Primary Structure amino cid sequence Secondary structure Helix Tertiary Structure polypeptide chain Quaternary Structure assembled subunits Important advances that established the modern era of biochemistry o 1953 Watson Crick deduced DNA structure implicit in their proposal was the idea that the sequence of nucleotide units genetically encoded information for proteins in DNA duplex o 1953 Sanger determind first complete amino acid sequence for any protein Insulin o 1957 Anfinsen proposed that primary protein sequence dictated its 3D native structure o 1959 Perutz Kendrew determined first high resolution structures of proteins myoglobin and hemoglobin o 1970 Smith discovered restriction enzymes ushering in modern molecular biology o 1980 Roche invented and marketed practical H saffinity tags Primary structural analysis what amino acids could be important o Examples of Modified Residues o Phosphorylation a common reversible protein modification Serine S threonine T tyrosine Y Large negative charge large electrostatic potential o Lysine K methylation acetylation ubiquitylation finished protein time for degradation sumoylation used to signal degradation Mono di tri o Serine S Threonine T Asparagine N Glycosylation sugar o Myristoylation addition of fatty acid by amid linkage on N terminus Irreversible FA are hydrophobic important in targeting proteins to membranes o Palmitoylation C terminus and cysteines addition of fatty acid Reversible modification aids in trafficking proteins to appropriate vesicles in organelles Also targets proteins to membranes AA sequence motifs can be signatures for function o Examples o