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14 Cards in this Set
- Front
- Back
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What are characteristics of nucleotide binding fold?
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1) Built on alpha-beta-alpha unit
2) "P-loop sensing proteins" 3) Cytoskeleton (tubulin, actin) |
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How is "Beta-alpha-beta" unit organized?
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32145(6) or 23145(6)
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What are "P-loop sensing proteins"?
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Small G-proteins
Motor proteins (myosin, kinesin) |
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What are characteristics of Immunoglobulin fold?
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1) 7 (9)-stranded all beta-sheet
-Strand order ---1254367--- (cylindrically wrapped) -N and C termini are at opposite ends of cylinder 2) MANY adhesion molecules- Fibronectin, cadherin, ICAM-1, lamin, intimin, invasin, and of course, Ig 3) Domains can be strung together |
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G-protein coupled receptor fold
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(1) 7 transmembrane helices
Specially built for membranes -(hydrophobic outside, all H-bonds satisfied internally) (2) >50% of all drugs target GPCR (3) Major drugs of abuse target GPCR -Cocaine, opioid, cannabinoid, etc |
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Globin fold
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1) All-alpha helix
2) Left hand model 3) Hemoglobin, myoglobin |
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How much free energy does it take to make proteins stable?
What fraction of unfolded proteins does this correspond to? |
-5 to -10 kcal/mol;
1/1000 |
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Examples of posttranslational modification
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Disulfides - cys
Phosphorylation - Ser, Thr, Tyr Hydroxylation - Pro, Lys (collagen) Glycosylation ---O-linked - Ser, Thr ---N-linked - Asn Carboxylation - glu (used in blood clotting sequence) Prenylation or fatty acid acetylation - ser, Lys, Cys, N-terminus Proteolysis - Any protein Protonation - Lysine, His, Glu, Asp, Cys, Tyr |
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True or false: peptide bonds of proteins can be broken by heating or high concentrations of urea
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False. Only prolonged exposure to strong acid or base at high temps will break peptide bonds nonenzymatically
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Facts about alpha-helix
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1) hydrogen bonds between peptide bond carbonyl oxygens and amide hydrogens 4 residues ahead
2) 3.6 amino acids per turn 3) side chains extend outward from central axis to avoid sterically interfering w ea |
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What disrupts alpha helix
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proline
large numbers of charged molecules amino acids with bulky side chains |
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Beta bends
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Reverse direction of polypeptide chain, helping it form compact globular structure
Consist of 4 amino acids, one proline found on surface of protein molecules Stabilized by formation of hydrogen and ionic bonds |
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Beta-sheet
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Unlike alpha-helix, 2 or more polypeptide chains are involved
H-bonds are perpendicular to the backbone |
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Isoforms
Isoenzymes |
proteins that perform the same function but are encoded by different genes with different primary structure; enzymes like above
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