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Protein Composition andStructure

Natalia PorcekMini Lecture

February 16, 2016

CentralDogma

• Proteins…– Function as catalysts– Transport and store other

molecules– Provide mechanical

support– Provide immune

protection– Generate movement– Transmit nerve impulses– Control growth and

differentiation

Building Blocks of Proteins

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Structure Function

How do you make a protein?

PrimaryStructure

• Aminoacidsarelinkedbypeptide(amide)bonds toformpolypeptidechains

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PolypeptideChain AminoAcidSequences HaveDirection

• A polypeptide chain has polarity

• The amino end is taken to be the beginning of a polypeptide chain

Amino Acid Sequences AreImportant• 1) Catalyticmechanisms canbeelucidated

– Mutationscauseproteinswithnovelproperties• 2) 3Dstructureofproteinscanbedetermined

– Linkbetween DNAandaprotein’sbiological function• 3)Molecularpathologycanbeexplored

– Alterations inaminoacidsequence cancausedisease (e.g., cysticfibrosisandsickle-cell anemia)

• 4) Evolutionaryhistorycanbeexamined– Similar aminoacidsequences=commonancestry– Molecularpaleontology

Sickle Cell Anemia

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DNAmRNAPrimaryStructureSecondaryStructureTertiaryStructureQuarternary Structure

Howdoesallofthisaffecttheprotein function?