Lecture_04_proteins

Lecture_04_proteins - Systems Human Physiology Lecture 4:...

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Systems Human Physiology Lecture 4: Protein interactions and enzymes 1
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READINGS : TODAY: CHAPTER 3 Sections C-D Tuesday: CHAPTER 3 section E-F 2
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Regulation of protein levels Protein interactions: Specificity Affinity Equilibrium Saturation Competition Enzymes Characteristics Regulation Today’s outline: 3
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DNA RNA Protein transcription translation splicing/alternative splicing degradation RNA degradation Regulation of protein amount in a cell 4 There is also regulation at the level of protein activity - we will talk about that today
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5 Protein Structures • Primary Protein Structure • Secondary Protein Structure • Tertiary Protein Structure • Quaternary Protein Structure
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6 Conformation • Proteins do not appear in nature like a linear string of beads on a chain. • Interactions between side groups of each amino acid lead to bending, twisting, and folding of the chain into a more compact structure. • The Fnal shape of a protein is known as its conformation .
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Primary structure - amino acid sequence Secondary structure - local 3D structures Tertiary structure - complete 3D structure PROTEIN FOLDING α helix β sheet Quaternary structure - aggregation of several protein subunits
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8 Primary Protein Structure Two variables determine the primary structure of a protein: (1) The number of amino acids in the chain (2) The specific type of amino acid at each position along the chain A polypeptide in the primary protein structure is analogous to a linear string of beads, each bead representing one amino acid.
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9 Secondary Protein Structure The attractions between various regions along a polypeptide chain creates secondary structure in a protein. Because peptide bonds occur at regular intervals along a polypeptide chain, the hydrogen bonds between them tend to force the chain into a coiled conformation known as an alpha helix . Hydrogen bonds can also form between peptide bonds when extended regions of a polypeptide chain run approximately parallel to each other, forming a relatively straight, extended region known as a beta pleated sheet .
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Tertiary Protein Structure • Once secondary structure has been formed, associations between additional amino acid side chains become possible. • These interactions fold the polypeptide into
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This note was uploaded on 03/09/2011 for the course IB 132 taught by Professor Brooks during the Spring '08 term at Berkeley.

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Lecture_04_proteins - Systems Human Physiology Lecture 4:...

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