CHMI E.R. Gauthier, Ph.D. 1 CHMI 2227E Biochemistry I Peptides - General structure and properties
CHMI E.R. Gauthier, Ph.D.2 Peptides A dipeptide
CHMI E.R. Gauthier, Ph.D.3 Peptides
CHMI E.R. Gauthier, Ph.D.4 Peptides - polarity
CHMI E.R. Gauthier, Ph.D.5 Peptides - nomenclature
CHMI E.R. Gauthier, Ph.D.6 Peptide: hydrolysis
CHMI E.R. Gauthier, Ph.D.7 High Pressure Liquid Chromatography (HPLC) PITC = phenylisothiocyanate PTC = phenylthiocarbamyl
CHMI E.R. Gauthier, Ph.D.8 High Pressure Liquid Chromatography (HPLC)
CHMI E.R. Gauthier, Ph.D.9 Peptide - ionization
CHMI E.R. Gauthier, Ph.D.10 Example of peptides 1. Aspartame: artificial sweetener 2. Oxytocin: stimulates uterine contractions Cys-Tyr-Ile-Gln-Asn-Cys-Pro-Leu-Gly-NH 2 Glycinamide residue: 2 HN-CH 2 -CONH 2 SS Disulfide bond H 3 N + -CH-C-NH-CH-C-OCH 3 COO - CH 2 O O Asp-Phe-methyl ester
CHMI E.R. Gauthier, Ph.D.11 Example of peptides 3.Insulin Intrachain disulfide bond Interchain disulfide bonds
CHMI E.R. Gauthier, Ph.D.12 Example of peptides 4.Cystic Fibrosis Transductance Regulator
CHMI E.R. Gauthier, Ph.D.13 General properties of proteins 1. Proteins differ in their Mr. Protein Mr (kDa) # residues # chains Insulin Cytochrome c Ribonuclease A Lysozyme Myoglobin Chymotrypsin Chymotrypsinogen Hemoglobin Serum albumin Hexokinase Immunoglobulin G1451,3204 RNA polymerase4504,1005 Apolipoprotein B5134,5361 Glutamate dehydrogenase 1,0008,30040 Source: Biochemistry. Lehninger.
CHMI E.R. Gauthier, Ph.D.14 Multimeric proteins Monomer/subunit Homodimer 1 1 Heterodimer 1 2 Hydrogen bonds: N-H O-H N-H N O-H O=C N-H O=C Hydrophobic interactions: -CH 3 CH 3 - CH 3 Electrostatic interactions: COO H 3 + N
CHMI E.R. Gauthier, Ph.D.15 Importance of multimeric proteins – planar cell polarity
CHMI E.R. Gauthier, Ph.D.16 Importance of multimeric proteins – planar cell polarity Nature Genetics 38, (2006)
CHMI E.R. Gauthier, Ph.D.17 General properties of proteins 2. Proteins differ in their pI. ProteinpI Pepsin1 Egg albumin4.6 Serum albumin4.9 Urease5 -lactoglobulin 5.2 Hemoglobin6.8 Myoglobin7 Chymotrypsinogen9.5 Cytochrome c10.7 Lysozyme11 Source: Biochemistry. Lehninger.
CHMI E.R. Gauthier, Ph.D.18 General properties of proteins 3. Frequency of amino acid composition Number of residues per molecule of protein Amino Acid Human cytochrome c Bovine chymotrypsinogen Ala622 Arg24 Asn515 Asp38 Cys210 Gln210 Glu85 Gly1323 His32 Ile810 Number of residues per molecule of protein Amino Acid Human cytochrome c Bovine chymotrypsinogen Leu619 Lys1814 Met32 Phe36 Pro49 Ser228 Thr723 Trp18 Tyr54 Val323 Total104245
CHMI E.R. Gauthier, Ph.D.19 General properties of proteins 3. Frequency of amino acid composition
CHMI E.R. Gauthier, Ph.D.20 General properties of proteins 4. Proteins can include other chemical groups in addition to amino acids ClassProsthetic group Example LipoproteinLipids 1-lipoprotein (blood) Glycoprotein Carbohydrates (sugars) Immunoglobulin G (blood) Phosphoprotein Phosphate groups Casein (milk) Hemoprotein Heme (iron porphyrin) Hemoglobin Flavoprotein Flavin nucleotides Succinate dehydrogenase Metalloprotein Fe Zn Ca Cu Ferritin Alcohol dehydrogenase Calmodulin Plastocyanin
CHMI E.R. Gauthier, Ph.D.21 General properties of proteins 5. Proteins have a specific shape Globular proteins Fibrillar (rod-like) proteins