华南理工大学：《食品分析》课程PPT教学课件（Food Analysis）Chapter 8 Amino Acid and Protein Analysis

Chapter 10 Amino acid Protein Analysis Qijun Wang 2005-4-12

Chapter 10 Amino acid & Protein Analysis Qijun Wang 2005-4-12

Chapter 10-1 Amino Acids Analysis

Chapter 10-1 Amino Acids Analysis

What is amino acid? What is amino acid? Amino Acid:aminated carboxylic acid (R-COOH) R group Carboxyl end Amino end

What is amino acid? What is amino acid? ◼ Amino Acid: aminated carboxylic acid (R-COOH) R group

Examples NH2CH2COOH NH2CH2CH2COOH a-amino B-amino acetic acid propanoic acid NH2CH2CH2CH2CH2CHCOOH NH2 a,8-2 amino caproic acid

NH2 CH2 COOH -amino acetic acid NH2 CH2 CH2 COOH -amino propanoic acid NH2 CH2 CH2 CH2 CH2 CHCOOH NH2 ，-2 amino caproic acid Examples

Classification of Amino Acid 1.By the location of Amino-group a/B/y-AA 2.By its acidity:neutral/acidic/basic AA ratio of Amino-group to carboxylic group 3.By whether containing phenyl group aromatic non aromatic AA 4.By its occurrence in protein Protein /non protein AA 5.By polarity of R group polar /apolar side chain AA 6.By its nutrient value to human: Essential AA and non-essential AA

Classification of Amino Acid 1. By the location of Amino-group ： / / -AA 2. By its acidity： neutral/ acidic/ basic AA ratio of Amino-group to carboxylic group 3. By whether containing phenyl group aromatic / non aromatic AA 4. By its occurrence in protein Protein / non protein AA 5. By polarity of R group : polar / apolar side chain AA 6. By its nutrient value to human: Essential AA and non-essential AA

20 a-AA commonly found in proteins a-aa structure Cn name En name NH2 甘氨酸 glycine CHCOOH NH2 丙氨酸 alanine CH-CHCOOH CH3 NH2 valine CH CH-CHCOOH 缬氨酸* CH3 NH2 亮氨酸* CH,CH-CH-CHCOOH leucine CH3 NH 异亮氨酸* CHCH CH-CHCOOH isoleucine

20 -AA commonly found in proteins -aa structure Cn name En name 甘氨酸 丙氨酸 缬氨酸* 亮氨酸* 异亮氨酸* glycine alanine valine leucine isoleucine NH2 CH2 COOH NH2 CH3 CHCOOH NH2 CH3 CH CHCOOH CH3 NH2 CH3 CH CHCOOH CH3 CH2 NH2 CH3 CH2 CHCOOH CH3 CH

Continued a-aa structure Cn name En name NH2 蛋氨酸* methionine CH SCHCH-CHCOOH CH-NH CH CH-CHCOOH 脯氨酸 proline N西 ○-cH-CHCOOH 苯丙氨酸* phenylalanine NH2 T CH CHCOOH 色氨酸* tryptophan NH2 HO-CH-CHCOOH 丝氨酸 serine

Continued -aa structure Cn name En name 蛋氨酸* 脯氨酸 苯丙氨酸* 色氨酸* 丝氨酸 methionine proline phenylalanine tryptophan serine NH2 CH3 SCH2 CH2 CHCOOH NH CHCOOH CH2 CH2 CH2 NH2 CH2 CHCOOH NH2 CH2 CHCOOH N H NH2 HO CH2 CHCOOH

continued a-aa structure Cn name En name HQ NH2 苏氨酸* threonine CHCH-CHCOOH NH2 HS-CHCHCOOH 半胱氨酸 cystine NH 酪氨酸 tyrosine H NH COCH-CHCOOH 天门冬酰胺 asparagine NH2 HNCOCHCH>-CHCOOH 谷酰胺 glutamine

continued -aa structure Cn name En name 苏氨酸* 半胱氨酸 酪氨酸 天门冬酰胺 谷酰胺 threonine cystine tyrosine asparagine glutamine NH2 CHCOOH HO CH3 CH NH2 HS CH2 CHCOOH NH2 HO CH2 CHCOOH NH2 NH2 COCH2 CHCOOH NH2 H2 NCOCH2 CH2 CHCOOH

continued a-aa structure Cn name En name NH2 天门冬氨酸 Aspartic HOOC-CH-CHCOOH acid NH2 谷氨酸 Glutamic HOOG-CHCH CHCOOH acid NH2 HNCH CHCHCH CHCOOH 赖氨酸* lysine NH NH2 HN-C-NH CH-CH2CH-CHCOOH 精氨酸 arginine NH2 N CH-CHCOOH 组氨酸 histidine

continued -aa structure Cn name En name 天门冬氨酸 谷氨酸 赖氨酸* 精氨酸 组氨酸 Aspartic acid Glutamic acid lysine arginine histidine CH2 NH2 HOOC CHCOOH CH2 CH2 NH2 HOOC CHCOOH NH2 H2 NCH2 CH2 CH2 CH2 CHCOOH NH2 H2 N CH2 CH2 CH2 CHCOOH NH C NH = H NH2 CH2 CHCOOH N N

Physical characteristics ALL the pure a-AAs are Colorless crystal,with quite high melting point (>200 deg.C)and water solubility

Physical characteristics ◼ ALL the pure -AAs are Colorless crystal , with quite high melting point (>200 deg.C) and water solubility