BCH 261 Lecture Notes - Lecture 6: Histidine, Tetrapeptide, Cystine
7 Jun 2018
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Page 1 of 9
Ryerson University – Winter 2018
BCH 261-011&071 Biochemistry - February 14th, 2018
BCH 261-011&071 Biochemistry - February 14th, 2018
Today’s Lecture: Amino Acids and Proteins
1. Amino acids
2. Peptide bonds
3. Protein prosthetic groups
4. Comparing protein sequences
5. Methods for protein purification and identification
Amino Acids
● Proteins are the workhorses of the cell
○ Catalysis - Enolase, DNA polymerase
○ Transport - Hemoglobin, Lactose Permease
○ Structure - Collagen, Keratin
○ Motion - Myosin, Actin
● Human genome encodes more than 20,000 proteins
● Examples of proteins you can see } Luciferin, Keratin, Hemoglobin
● Proteins are polymers of amino acids
○ Heteropolymers of the 20 common amino acids
○ Amino acids have properties well suited for biological functions
○ Common general structure of an amino acid
■ Amino group
■ Carboxyl group
■ R group / side chain
■ Exists in a non-ionic or zwitterionic form
Page 2 of 9
Ryerson University – Winter 2018
BCH 261-011&071 Biochemistry - February 14th, 2018
Every amino acid also has another atom or group of atoms bonded to the central atom à R group
R group determines the identity of the amino acid
Example: if the R group is a hydrogen atom, then the amino acid is glycine, while if it’s a
methyl group (CH3), the amino acid is alanine.
The twenty common amino acids are shown in the chart on the next page of the notes, with their
R groups highlighted in blue.
Classification of Amino Acids
● Nonpolar, aliphatic (no ring structure) (7)
○ Contain hydrocarbon groups with no charge
○ Glycine, Alanine, Valine, Leucine, Isoleucine, Phen
● Aromatic (3)
● Polar uncharged (5)
○ Have functional groups that easily interact with water through H+ bonding
○ Contains a hydroxyl group
○ Serine, Cysteine, Threonine, Asparagine, Glutamine
● Polar charged (3)
○ Positively charged at pH 7.2
○ Histidine, Lysine, Arginine
● Negatively charged (2)
○ Side chains with a carboxylate group that ionizes at physiological pH 7.2
○ Aspartate, Glutamate
*Memorize/know abbreviations of standard amino acids
Type of questions that will be on midterm:
● Given an amino acid, determine group and/or corresponding abbreviation
● Draw structure of amino acid or name amino acid given structure
Page 3 of 9
Ryerson University – Winter 2018
BCH 261-011&071 Biochemistry - February 14th, 2018
Document Summary
Today"s lecture: amino acids and proteins: amino acids, peptide bonds, protein prosthetic groups, comparing protein sequences, methods for protein purification and identification. Proteins are the workhorses of the cell. Human genome encodes more than 20,000 proteins. Examples of proteins you can see } luciferin, keratin, hemoglobin. Heteropolymers of the 20 common amino acids. Amino acids have properties well suited for biological functions. Common general structure of an amino acid. Exists in a non-ionic or zwitterionic form. Every amino acid also has another atom or group of atoms bonded to the central atom r group. R group determines the identity of the amino acid. Example: if the r group is a hydrogen atom, then the amino acid is glycine, while if it"s a methyl group (ch3), the amino acid is alanine. The twenty common amino acids are shown in the chart on the next page of the notes, with their. Have functional groups that easily interact with water through h+ bonding.
