Amino Acids & Peptides. BIOMEDICAL IMPORTANCE the monomer units – L-α-amino Cellular functions...

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Amino Acids & Peptides

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  • Slide 1
  • Amino Acids & Peptides
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  • BIOMEDICAL IMPORTANCE the monomer units L--amino Cellular functions Nerve transmission Biosynthesis of porphyrins Purines Pyrimidines Urea
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  • Biomedical Importance Peptides Neuroendocrine system as hormones, hormone-releasing factors, Neuromodulators,or neurotransmitters
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  • One- & three-letter Additional amino acids arise by modification methylation, formylation, acetylation, prenylation, and phosphorylation
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  • L- -Amino acids present in proteins.
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  • Amino Acids May Have Positive, Negative, or Zero Net Charge
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  • Zwitterions equal number of ionizable groups of opposite charge pK a Express the Strengths of Weak Acids
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  • Protonic equilibria of aspartic acid.
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  • The net charge on an amino acid Depends upon the pK a values of its functional groups the pH of the surrounding medium At Its Isoelectric pH (pI), an amino acid bears no net charge
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  • For lysine, pI is calculated from: the pI for aspartic acid
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  • Typical range of pKa values for ionizable groups in proteins.
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  • Amino Acid Sequence Determines Primary Structure
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  • Peptide Structures
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  • Some Peptides Contain Unusual Amino Acids
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  • Glutathione (-glutamyl-cysteinylglycine). Note the non- peptide bond that links Glu to Cys.
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  • Peptides Are Polyelectrolytes The Peptide Bond Has Partial Double-Bond Character
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  • The four atoms of the peptide bond (colored blue) are coplanar