PROTEIN AND PEPTIDE STRUCTURE*

Table of Contents

{1} PROTEIN AND PEPTIDE STRUCTURE*

{2} Proteins fold into compact structures.

{3} Primary structure

{4} Always referred to...

{5} Key lies in rotation about main-chain bonds

{6} There are THREE repeating torsion angles

{7} OMEGA angle tends to be planar

{8} Trans is generally favored over cis:

{9} Leaves phi and psi for flexible folding...

{10} When these phi/psi torsion angles repeat

{11} Repeating Phi= -57, Psi= -47 gives...ALPHA HELIX

{12} Stability of this helical

{13} Cytochrome b562 is mostly alpha-helix

{14} Phi = -119, Psi = +113 gives...BETA SHEET

{15} In larger portions

{16}  Phi= -139, Psi=+135 gives the antiparallel BETA SHEET.

{17} Plastocyanin is mostly beta-sheet.

{18} These structural elements defined by...

{19} However, there is another kind of secondary structure

{20} Proline is often found in turns

{21} ...sometimes with cis peptide bonds

{22} "Tertiary" Structure

{23} Tertiary structure...

{24} by covalent crosslinks,

{25} by non-bonding interactions,

{26} by non-bonding interactions,

{27} Quaternary (4°) Structure

{28} Quaternary Structure...

{29} e.g. the two chains of insulin

{30} More subunits give more symmetry choices...

{31} Thus...

Email: wampler@bchiris.bmb.uga.edu

Home Page: http://bmbiris.bmb.uga.edu/wampler/8010

ASSIGNMENT:

Chapter 4 of Garret & Grisham

Chapters 1 and 2 of Branden & Tooze

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