3. Some proteins contain chemical groups other han amino acids 3.1 Many proteins contain only amino acids, e. g insulin, ribonuclease A, chymotrypsin. 3.2 Some proteins(conjugated proteins) contain other components 3.2.1 Cytochrome c and myoglobin contain heme groups. Immunoglobulin G contains carbohydrate groups
3. Some proteins contain chemical groups other than amino acids 3.1 Many proteins contain only amino acids, e.g., insulin, ribonuclease A, chymotrypsin. 3.2 Some proteins (conjugated proteins) contain other components. 3.2.1 Cytochrome c and myoglobin contain heme groups. Immunoglobulin G contains carbohydrate groups
3.2.2TI he non-amino acid parts are usuall called prosthetic groups and the protein part alone called apoprotein. (holoenzyme=apoenzyme+substrates+ cofactors+prosth etic groups) 3.2.3 Prosthetic groups usually play important roles for protein functions 3.2.4 The conjugated proteins are usually classified according to the nature of their prosthetic groups。 Lipoproteins: lipids Glycoproteins: carbohydrate groups Metalloproteins: different metals (ions)
3.2.2 The non-amino acid parts are usually called prosthetic groups and the protein part alone called apoprotein. (holoenzyme=apoenzyme+substrates+cofactors+prosth etic groups) 3.2.3 Prosthetic groups usually play important roles for protein functions. 3.2.4 The conjugated proteins are usually classified according to the nature of their prosthetic groups. Lipoproteins: lipids Glycoproteins: carbohydrate groups Metalloproteins: different metals (ions)
4. The amino acid sequence of short polypeptide chains can be determined by y chemical methods 4.1 Amino acid sequence of a peptide chain is the identity and linking order of its amino acid residues. No other properties so clearly distinguish one peptide from another. 4.2 Sanger worked out the first amino acid sequence of a peptide(bovine insulin) in 1953
4. The amino acid sequence of short polypeptide chains can be determined by chemical methods. 4.1 Amino acid sequence of a peptide chain is the identity and linking order of its amino acid residues. No other properties so clearly distinguish one peptide from another. 4.2 Sanger worked out the first amino acid sequence of a peptide (bovine insulin) in 1953
He accomplished this by using l-fluoro-2, 4- dinitrobenzene(1-氟-2,4-硝基苯) to react with the N-terminal residues of cleaved short peptides. 100 g of insulin were consumed over ten years to determine the sequence. The peptide chains were cut into 150 fragments of different lengths. He was awarded the nobel Prize in 1958 in chemistry for this breakthrough nvention
He accomplished this by using 1-fluoro-2,4- dinitrobenzene(1- 氟-2，4-硝基苯）to react with the N-terminal residues of cleaved short peptides. 100 g of insulin were consumed over ten years to determine the sequence. The peptide chains were cut into 150 fragments of different lengths. He was awarded the Nobel Prize in 1958 in chemistry for this breakthrough invention
4.3 The amino acid sequence of a short peptide can be efficiently determined by Edman degradation(埃德曼 降解) 4.3.1 The uncharged terminal amino group is reac ted with phenylisot isocyanate(苯异硫氰酸盐,异 硫氰酸 o form a phenylthiocarbamyl(苯氨基硫代甲 酰基) peptide 4.3.2 The N-terminal amino acid residue is liberated as a cyclic phenylthiohydantoin(PTh) derivative under mildly acid conditions, leaving the rest of the peptide chain intact. 4.3.3 The PTH derivative(thus the amino acid residue) can be identified by chromatographic methods 4.3.4 The newly exposed N-terminal amino acid residue can be identified by repeating the above procedure
4.3 The amino acid sequence of a short peptide can be efficiently determined by Edman degradation(埃德曼 降解）. 4.3.1 The uncharged terminal amino group is reacted with phenylisothiocyanate(苯异硫氰酸盐,异 硫氰酸)to form a phenylthiocarbamyl(苯氨基硫代甲 酰基) peptide. 4.3.2 The N-terminal amino acid residue is liberated as a cyclic phenylthiohydantoin (PTH) derivative under mildly acid conditions, leaving the rest of the peptide chain intact. 4.3.3 The PTH derivative (thus the amino acid residue) can be identified by chromatographic methods 4.3.4 The newly exposed N-terminal amino acid residue can be identified by repeating the above procedure