Chapter 3b

[object Object],[object Object],[object Object],[object Object]

Amino acid in H 2 O ,[object Object],[object Object],[object Object],Fig 3-9, p.79

Chemical properties of A.A. ,[object Object],[object Object],p. 79 C COO - H R NH 3 + Net charge: + 1 - 1 0 R C COO - H NH 2 H + C COOH H R NH 3 + H + H + H +

K a : dissociation constant ,[object Object],p  = - log  兩邊倒數，取 log At K eq, [HA] = [A - ]  At K eq , pH = p K a CH 3 COOH H + + CH 3 COO - HA H + + A - K eq = = K a [H + ] [A - ] [HA] = log [H + ] [A - ] [HA] 1 K a log

Titration curve of Gly (I) ,[object Object],Fig 3-10, p.79

Titration curve of Gly (II) ,[object Object],[object Object],[object Object],Fig 3-10 pI = ½ (pK 1 + pK 2 )

What is isoelectric point (pI)? ,[object Object],[object Object],pH 14 pH 1 AA - AA + AA ++++++++ -------- Lys + pI=9.7 Arg + pI=10.8 Glu - pI=3.2 Asp - pI=2.7

Titration curve of Glu ,[object Object],Fig 3-12a, p.81 pI = ½ (pK 1 + pK R )

Titration curve of His ,[object Object],[object Object],Fig 3-12b, p.81 pI = 7.59

Amino Acid  Monomer  Polymer Peptide, Polypeptide, Protein

The Peptide Bond ,[object Object],[object Object],[object Object],Fig 3-13, p.82 (condensation) (hydrolysis)

Peptide and Polypeptide ,[object Object],[object Object],[object Object],a.a. 1 a.a. 2 a.a. 3 ….. Peptide Chain N-terminal C-terminal

Peptide chain Fig 3-14, p.82 Ser – Gly – Tyr – Ala - Leu

NutraSweet (aspartame) ,[object Object],[object Object],[object Object],p. 83

Chemical properties of peptides ,[object Object],[object Object],[object Object],[object Object],Fig 3-15, p.83

“ Protein” ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],p. 86-87  1  2  1  2

Table 3-1 modified ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],p.84, right column Amino acid 　 M r Occurence % Gly 75 7.2 Ala 89 7.8 Val 117 6.6 Leu 131 9.1 Ile 131 5.3 Met 149 2.3 Phe 165 3.9 Tyr 181 3.2 Trp 204 1.4 Ser 105 6.8 Pro 115 5.2 Thr 119 5.9 Cys 121 1.9 Asn 132 4.3 Gln 146 4.2 Lys 146 5.9 His 155 2.3 Arg 174 5.1 Asp 133 5.3 Glu 147 6.3 Average 136.8 129.0

Conjugated proteins ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]

Chapter 3b

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Chapter 3b