Amino Acids

Amino Acids

1. Zwitterion

   • A amino acid that has a protonated amino group and a deprotonated carboxylic group

2. Isoelectrical Point, pI

   • pH mellem anionic and cationic
   • Sure +neutrale aminosyre
     • pI= 1/2 (pKa1+pKa2)
   • Basiske aminosyre
     • pI = 1/2 ( pKa2+pKa3)

3. Synthesis of alpha-amino acids

   • Enantioselective Synthesis
     • Enantioselective synthesis
     • To resolve the racemate into its pure enantiomers
   • Reductive Amination of alpha-keto acids
     • Alpha-keto acids
   • The Amidomalonate Synthesis
     • Sn2 alkylation
     • enolate ion
     • Decarboxylation
     • Malonic ester synthesis

4. Amphiprotic

5. Proteinerge

   • Dansk ord Aminosyre der indgår som byggesten i peptider og proteiner
   • Peptides
     • n < 50 = Peptid (n = antallet af aminosyre)
     • Written
     • Peptide Synthesis
       • Beskyttelsesgrupper
         • Beskyttelsesgrupper (Pn, Ps og Pc) bruges til at beskytte de reaktive funktionelle grupper, der ikke skal deltage i amidbindingen
         • Amino group (Pn)
           • Boc
             • Tert-butoxycarbonylgruppe Den mest almindelige måde at få BOC på en ubeskyttet aminosyre er vha. BOC2O (tert-butylpyrocarbonat)
             • Fjernelse
               • Fjernelse af BOC-grupper foretages altid vha. syre Oftest med trifloureddikesyre (TFA), der dannes carbondioxid og isoutylen
           • Fmoc
             • Flourenylmethoxycarbonyl-gruppen Most commonly used N-protecting group for fast fase Fmoc-OSu benyttes til introduktion
             • Fjernelse
               • Fmoc fjenes med behandling af en sekundær amin (normalt piperidin)
           • Z-gruppen
             • BenZyloxycarbonyl - Indføres vha. benzyloxycarbonylchlorid (Z-Cl) som er et syrechlorid
           • Estere
             • Syrespaltelig
               • Repræsenteres i bioorganisk kemi af Tert-butylestere
             • Basespaltelige
               • Methyl- og ethylestere
             • Hydrogenolyserbare
               • Benzylestere spaltes bedst via hydrogenolyse
         • Carboxyl group (Pc)
           • Converting
             • Carboxyl groups are often protected by converting them into methyl or benzyl esters. - They are easily introduced by ester formation - Easily removed by mild hydrolysis with aq. NaOH
         • Sidekæde (Ps)
           • Det kan også være nødvendigt at beskytte sidekæder med reaktive substituenter
           • Basisk sidekæder
             • Lysin
             • Arginin
             • Histidin
             • Tryptophan
           • Sure sidekæder
             • OH som sidegrup
               • Serin
               • Threonin
               • Phenol
                 • Tyrosin
             • COOH som sidegrup
               • Asparagin
               • Glutamin
           • Svovl
       • Merrifield
     • Peptide Sequencing
       • What order the amino acids are linked together
       • Mass Spectroscopy
         • Electrospray ionization (ESI)
         • Matrix-assisted laser desorption ionization (MALDI)
           • described in 10.4
           • Time-Of-Flight (TOF) mass analyzer
         • Edman degration
           • Involves treatment of a peptide with phenyl isothiocyanate (PITC) followed by a treatment with triflouroacetic acid yields an anilinothiazolinone (ATZ). Aqueous acid is the used to convert ATZ into phenylthiohydantoin (PTH)
           • Sequencing of large proteins by Edmand digression is impractical because of the buildup of unwanted by-product
           • PITC
             • Reagents: Phenyl isothiocyanate (PITC)
           • ATZ
             • Yields an intermediate:  anilinothiazolinone (ATZ) derivative
           • PTH
             • Product: Phenylthiohydantoin (PTH)
     • Nomenklatur
       • N-terminal
         • N-terminalen er til venstre, og her starter numeringen
       • C-terminal
         • C-terminalen er til højre
     • CPP
       • Cell-penetration peptides
   • Proteins
     • n > 50 = Protein  (n = antallet af aminosyre)
     • Isoelectrical Point, pI
     • Proteins backbone
       • The long repetitive sequence of N-CH-CO atoms that makes up a continuous chain
   • Amina acid analyzer

6. Non-proteinerge

   • Findes i prokaryoter og laver eukaryoter

7. L/D-Nomeklatur

   • Amino gruppen skal være til "left" for at det er L form Amino gruppen skal være til højre hvis det er D form

8. Aminosyre syntese

   • Strecker syntesen
     • En adehyd eller keton reagere med ammoniak eller en amin og cyanid.

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