生物化學(xué)教學(xué)課件：Chapter 1Amino Acids,Peptides and Proteins-1

1、Chapter 1Amino Acids, Peptides and Proteins-1 -Amino acids漁 魚(yú) Summary一、氨基酸的結(jié)構(gòu)二、氨基酸的類型三、氨基酸的理化性質(zhì)Proteins are polymers of amino acids.The cell can produce proteins with strikingly different properties and activities by joining the same 20 amino acids in many different combinations and sequences.Amino

2、AcidsGeneral structure R groupThe amino acid residues in protein molecules are exclusively L stereoisomers一、氨基酸的結(jié)構(gòu)OR OH NH2 CH2SH COOH CHO CH2OH CH3 H。based on R group, the amino acids can be classified as:1. Nonpolar and aliphatic2. Aromatic (generally nonpolar)3. Polar but uncharged4. Negatively c

3、harged5. Positively charged二、氨基酸的類型Relative mutability of amino acids (Ala=100)Ala: 100.000 Arg: 65.000 Asn: 134.000 Asp: 106.000 Cys: 20.000 Gln: 93.000 Glu: 102.000 Gly: 49.000 His: 66.000 Ile: 96.000 Leu: 40.000 Lys: 56.000 Met: 94.000 Phe: 41.000 Pro: 56.000 Ser: 120.000 Thr: 97.000 Trp: 18.000

4、Tyr: 41.000 Val: 74.000 Hydrophobicity of physiological L-alpha amino acids Ala: 0.616 Arg: 0.000 Asn: 0.236 Asp: 0.028 Cys: 0.680 Gln: 0.251 Glu: 0.043 Gly: 0.501 His: 0.165 Ile: 0.943 Leu: 0.943 Lys: 0.283 Met: 0.738 Phe: 1.000 Pro: 0.711 Ser: 0.359 Thr: 0.450 Trp: 0.878 Tyr: 0.880 Val: 0.825 Unco

5、mmon Amino Acids 4羥(基)脯氨酸5羥(基)賴氨酸硒代半胱氨酸鏈霉素6N甲基賴氨酸 羥基谷氨酸About 300 kinds of amino acids not occurring in proteins, but can be found in cells. All are derived from common amino acids.Amino acids act as acids and basesAmino acids exist in solution as zwitterion. It can yield protons from COOH or NH2 group三、氨基酸的理化性質(zhì)Characteristic titration curves of amino acids Tryptophan and tyrosine absorb ultraviole