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| a-b barrels (the TIM fold) |
-This fold has 8 stranded parallel b barrel concentric with 8 outer a helices.
-active sites on C terminal side of b strand loop regions |
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mcs5109 Tue, 21 Oct 2008 21:11:22 GMT |
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| b barrels |
-Diverse group
-4 to over 10 antiparallel strands
-typically 2 b sheets that pack against each other
-looks like barrel |
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mcs5109 Tue, 21 Oct 2008 21:09:29 GMT |
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| The globin fold |
-Globin fold found in myoglobin, hemoglobin
-8 a helices bundle
-forms a pocket for the active site (such as heme)
-Protects heme from contact with other heme |
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mcs5109 Tue, 21 Oct 2008 21:09:29 GMT |
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| a-a motifs |
4 a helices in a bundle
-residues contacting each other in the bundle are hydrophobic |
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mcs5109 Tue, 21 Oct 2008 21:09:29 GMT |
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| b-a-b motif |
-Connection between strands of parallel b-sheets are frequently made by a-helix
-motif has b-strand, loop, a-helix, loop and b-strand
-common in parallel b-sheets
Helical axis usually parallel with that of b-sheet
-Helix and sheet pack hydrophobic residues
-loops often active sites
-right handed |
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mcs5109 Tue, 21 Oct 2008 21:09:28 GMT |
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| Hairpin b motifs |
This motif is two adjacent antiparallel strands joined by a loop. Called either a hairpin or a b-b unit |
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mcs5109 Tue, 21 Oct 2008 21:03:32 GMT |
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| Supersecondary structures |
-Building blocks for proteins
bab motif
b hairpin motif
aa motif
Greek key motif |
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mcs5109 Tue, 21 Oct 2008 21:03:32 GMT |
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| Side chain location varies with polarity: |
-tendency to hide hydrophobic residues
-Val, Leu, Ile, Met and Phe in interior
-When in interior, always hydrogen bonded.
-H bond ‘neutralizes’ charge so that it can go to interior |
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mcs5109 Tue, 21 Oct 2008 21:03:31 GMT |
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| Globular proteins |
-spherical molecules
-Some proteins have just a helix (myoglobin), others have a large proportion of b sheets (concanavalin A).
Most proteins have significant amounts of both (carbonic anyhydrase. |
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mcs5109 Tue, 21 Oct 2008 21:03:31 GMT |
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