* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Download amino acids
Survey
Document related concepts
Citric acid cycle wikipedia , lookup
Synthetic biology wikipedia , lookup
Self-assembling peptide wikipedia , lookup
Nucleic acid analogue wikipedia , lookup
Protein adsorption wikipedia , lookup
Bottromycin wikipedia , lookup
Fatty acid metabolism wikipedia , lookup
List of types of proteins wikipedia , lookup
Intrinsically disordered proteins wikipedia , lookup
Protein (nutrient) wikipedia , lookup
Cell-penetrating peptide wikipedia , lookup
Peptide synthesis wikipedia , lookup
Proteolysis wikipedia , lookup
Protein structure prediction wikipedia , lookup
Genetic code wikipedia , lookup
Transcript
Lecture Presentation Chapter 19 Amino Acids and Proteins Karen C. Timberlake General, Organic, and Biological Chemistry: Structures of Life, 5/e Karen C. Timberlake © 2016 Pearson Education, Inc. Chapter 19 Amino Acids and Proteins • Radiology technicians work with radiologists to produce images that allow for the diagnosis and treatment of certain medical conditions. • Technicians operate imaging equipment such as X-ray, computed tomography (CT), and positron emission tomography (PET). General, Organic, and Biological Chemistry: Structures of Life, 5/e Karen C. Timberlake © 2016 Pearson Education, Inc. Chapter 19 Readiness Key Math Skill • Calculating pH from [H3O+] (11.6) Core Chemistry Skills • Writing Equations for Reactions of Acids and Bases (11.7) • Naming Carboxylic Acids (16.1) • Forming Amides (18.5) General, Organic, and Biological Chemistry: Structures of Life, 5/e Karen C. Timberlake © 2016 Pearson Education, Inc. 19.1 Proteins and Amino Acids Protein molecules, compared with many of the compounds we have studied, can be gigantic. The horns of animals are made of proteins. Learning Goal Classify proteins by their functions. Give the name and abbreviations for an amino acid, and draw its zwitterion. General, Organic, and Biological Chemistry: Structures of Life, 5/e Karen C. Timberlake © 2016 Pearson Education, Inc. Functions of Proteins Proteins • in the body are polymers made from 20 different amino acids. • differ in characteristics and functions that depend on the order of amino acids that make up the protein. • form structural components such as cartilage, muscles, hair, and nails. • function as enzymes to regulate biological reactions such as digestion and cellular metabolism. • including hemoglobin and myoglobin transport oxygen in the blood. General, Organic, and Biological Chemistry: Structures of Life, 5/e Karen C. Timberlake © 2016 Pearson Education, Inc. Structural Classification of Proteins and Functions General, Organic, and Biological Chemistry: Structures of Life, 5/e Karen C. Timberlake © 2016 Pearson Education, Inc. Amino Acids Amino acids, the molecular building blocks of proteins, have a central carbon atom called the α carbon, bonded to • two functional groups: an ammonium group (— NH3+) and a carboxylate group (— COO−) • a hydrogen atom and an R group or side chain in addition to the carboxylate and ammonium groups. General, Organic, and Biological Chemistry: Structures of Life, 5/e Karen C. Timberlake © 2016 Pearson Education, Inc. Zwitterions At physiological pH, the • ionized ammonium and carboxylate groups give an amino acid a balance of positive and negative charge, which gives an overall zero charge. • neutral amino acid, which is called a zwitterion, occurs at a specific pH value known as its isoelectric point (pI). Core Chemistry Skill Drawing the Zwitterion for an Amino Acid General, Organic, and Biological Chemistry: Structures of Life, 5/e Karen C. Timberlake © 2016 Pearson Education, Inc. Classification of Amino Acids Amino acids are classified using their specific R groups. The • nonpolar (hydrophobic) amino acids have hydrogen, alkyl, or aromatic R groups. • polar amino acids have R groups that interact with water, which makes them hydrophilic. • polar neutral amino acids contain an hydroxyl (— OH), a thiol (— SH), or an amide (— CONH2) R group • polar acidic amino acids contain a carboxylate (— COO−) R group. • polar basic amino acids contain an ammonium (— NH3+) R group. General, Organic, and Biological Chemistry: Structures of Life, 5/e Karen C. Timberlake © 2016 Pearson Education, Inc. Classification of Amino Acids A summary of amino acid types and their interactions with water General, Organic, and Biological Chemistry: Structures of Life, 5/e Karen C. Timberlake © 2016 Pearson Education, Inc. Nonpolar Amino Acids An amino acid is nonpolar when the R group is H, alkyl, or aromatic. General, Organic, and Biological Chemistry: Structures of Life, 5/e Karen C. Timberlake © 2016 Pearson Education, Inc. Polar Amino Acids, Neutral R Groups An amino acid is polar when the R group is an alcohol, a thiol, or an amide. General, Organic, and Biological Chemistry: Structures of Life, 5/e Karen C. Timberlake © 2016 Pearson Education, Inc. Amino Acids, Charged R Groups An amino acid is charged when the R group is a carboxylate (— COO−) or an ammonium (— NH3+) group. General, Organic, and Biological Chemistry: Structures of Life, 5/e Karen C. Timberlake © 2016 Pearson Education, Inc. Study Check Draw the zwitterions for the amino acids serine and aspartate. General, Organic, and Biological Chemistry: Structures of Life, 5/e Karen C. Timberlake © 2016 Pearson Education, Inc. Solution Draw the zwitterions for the amino acids serine and aspartate. ANALYZE THE PROBLEM Given serine aspartate Serine General, Organic, and Biological Chemistry: Structures of Life, 5/e Karen C. Timberlake Need draw the zwitterions Aspartate © 2016 Pearson Education, Inc. Amino Acid Abbreviations Amino acids have • three-letter abbreviations derived from their names, given in Table 19.2. • one-letter abbreviations to allow the faster transfer of data. Of the 20 amino acids, • 11 have one-letter abbreviations that are the same as the first letter in their names and 9 use different letters. • arginine R and tyrosine Y use the second letters in their names; phenylalanine is F; and lysine is K, which is near L in the alphabet. General, Organic, and Biological Chemistry: Structures of Life, 5/e Karen C. Timberlake © 2016 Pearson Education, Inc. Amino Acid Stereoisomers Amino acids can exist as D and L stereoisomers called enantiomers. We draw Fischer projections for α-amino acids by placing • the carboxylate group at the top. • the R group at the bottom. • the — NH3+ group of the L isomer on the left. • the — NH3+ group of the D isomer on the right. General, Organic, and Biological Chemistry: Structures of Life, 5/e Karen C. Timberlake © 2016 Pearson Education, Inc. Study Check Identify the following amino acids as D or L enantiomers: COO – + A. H N––C––H 3 CH2 B. H COO – + C ––NH3 CH2 OH General, Organic, and Biological Chemistry: Structures of Life, 5/e Karen C. Timberlake © 2016 Pearson Education, Inc. Solution Identify the following amino acids as D or L enantiomers: COO – + A. H N––C––H 3 CH2 B. H COO – + C ––NH3 CH2 OH L-Phenylalanine General, Organic, and Biological Chemistry: Structures of Life, 5/e Karen C. Timberlake D-Serine © 2016 Pearson Education, Inc. Chemistry Link to Health: Essential Amino Acids Of the 20 amino acids used to build the proteins in the body, • only 11 can be synthesized in the body; • the other 9 are essential amino acids that must be obtained from the proteins in the diet. General, Organic, and Biological Chemistry: Structures of Life, 5/e Karen C. Timberlake © 2016 Pearson Education, Inc. Chemistry Link to Health: Essential Amino Acids Complete proteins such as eggs, milk, meat, and fish contain all of the essential amino acids. Incomplete proteins from plants such as grains, beans, and nuts are deficient in one or more essential amino acids. General, Organic, and Biological Chemistry: Structures of Life, 5/e Karen C. Timberlake © 2016 Pearson Education, Inc.