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20 Cards in this Set
- Front
- Back
Nuclear Magnetic Resonance spectroscopy
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atomic nuclei possess a property called spin; when placed in an external static magnetic field, the nuclear spin will precess around the axis of the external magnetic field at a specific resonance frequency known as the chemical shift.
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nuclear Overhauser effect
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the nuclei of individual atoms interact with one another in a way that can be correlated with the internuclear distance by which they are separated.
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X-ray crystallography
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The protein crystal is then irradiated with a high intensity X-ray beam, which is diffracted by the protein crystal to form a pattern of spots known as a diffraction pattern.
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peptide bonds
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amino acids are joined end-to-end by amide bonds between the alpha-amino group of one amino acid and the alpha-carboxyl group of another amino acid
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primary structure
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The sequence of amino acids in a protein
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N-terminus
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amino-terminal end of a polypeptide chain
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C-terminus
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carboxyl-terminal end of a polypeptide chain
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The conformation of a polypeptide chain is partly constrained because
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rotation around a peptide bond is prevented by the partial double bond character of this bond
groups lie in a plane |
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secondary structure
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Helical and sheet structures formed from folded polypeptide chains
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Protein secondary structures exist 1
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only certain combinations of the backbone dihedral angles phi and psi eliminate steric clashes between backbone and sidechain atoms of adjacent amino acid residues.
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Protein secondary structures exist 2
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opportunities for hydrogen bond formation exist when polypeptide chains adopt helical and sheet conformations
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alpha-helix
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This structure can be represented by a right spiral staircase with amino acids for steps.
Side chains project away from the center. Hydrogen bonds between the backbone amide group of an amino acid and the backbone carbonyl group of another amino acid four steps away stabilize the alpha-helix. |
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beta-sheet
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One extended polypeptide chain (designated as a beta-strand) hydrogen bonds with another polypeptide chain (another beta strand) to form a beta-sheet.
Side chains project either above or below the beta-sheet. often see branched sidechains |
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collagen helix
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"stretched alpha-helix” which lacks intrastrand hydrogen bonds
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Tertiary structure
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the three-dimensional structure of a polypeptide chain.
stabilized by hydrogen bonds, electrostatic bonds, hydrophobic interactions and, in certain cases, disulfide bonds. |
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Disulfide bonds
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by oxidation between the sulfhydryl groups of the side chains of cysteine residues that are in close spatial proximity
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denaturation
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The process of losing protein structure
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denaturation reagents
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break hydrogen bonds, such as urea and guanidine hydrochloride
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renature
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refold and become active if reagent is removed by dialysis
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Quaternary structure
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the arrangement of polypeptides in aggregates that have several polypeptides.
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