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18 Cards in this Set
- Front
- Back
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Steric Interactions |
Excluded volume interactions. Two atoms cannot occupy the same region of space simultaneously. Electron clouds of atoms overlap. Short range repulsion, only important at very short distances. |
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Formation of Peptide Bond |
Results on the liberation of one water molecule per two amino acids condensed. Hydrolysis is favoured thermodynamically in aqueous media. Still requires enzymes |
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Geometry of a peptide bond |
A peptide bond is most accurately represented as a hybrid of two contributing structures. |
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Resonance in the peptide bond |
The peptide group is a rigid planar structure due to the resonance interactions which give the peptide bond an ~ 40% double bond character. |
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Planar character of the peptide bond |
Partial double bond character prevents the peptide bond from rotating. 2 Configurations are possible. Trans and Cis. Trans is the favoured configuration particularly with bulky R groups. Cis configuration is very rare. |
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Protein Synthesis |
The thermodynamic instability of polypeptides requires a mechanism other than a straightforward dehydration reaction for their synthesis in the aqueous media of the cell. Coupling to ATP hydrolysis is involved. |
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Polypeptide definition |
Amide bonds between the alpha carboxyl group of one amino acid group and the alpha amino group of another. |
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Amino Acid Residue |
The portion of the original amino acid that remains in the peptide. |
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Oligopeptides |
peptides with only a few AA residues. |
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Polypeptides |
Long chains of peptides with many AA residues. A macromolecule containing many amino acids joined by peptide bonds. |
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Peptide |
The name given to a short polymer of of amino acids joined by peptide bonds. They are classified by the number of amino acids in the chain |
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Dipeptide |
A molecule containing two amino acids joined by a peptide bond. |
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Tripeptide |
A molecule containing three amino acids joined by peptide bonds |
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Protein |
A biological macromolecule consisting of one or more polypeptide chains. Polypeptides of defined sequence. Each protein has a defined order of amino acid residues. This sequence is referred to as the primary structure of the protein. |
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Writing Peptides |
By convention, peptides are written from the left, beginning with the free -NH3 group and ending with the free CO2 group |
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The sequence of amino acids in a protein |
A unique characteristic of every protein. Is encoded by the nucleotide sequence of DNA. Is thus a form of genetic information. Is read from the amino terminus to the carboxyl terminus. |
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MALDI Mass Spectrometer |
Ions are generated by a laser firing at the target plate. The time of firing of the laser and the arrival time of the ions at the detector are known, the relative masses can then be calculated. Only single charged ions are generated. |
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Solid Phase peptide synthesis |
A cyclical three step process. 1. deprotection 2. activation. 3. coupling. |
