BABS1201 Lecture Notes - Lecture 4: Amine, Carboxylic Acid, Peptide
17 May 2018
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BABS1201
12TH MARCH 2018
MACROMOLECULES II
BRIEFLY DESCRIBE THE GENERAL STRUCTURAL FEATURES OF PROTEINS – (CHAPTER 5, CONCEPT 5.4)
× Proteins are polymers of amino acid monomers- these polymers are commonly called
polypeptides
- When small numbers of amino acids join together, they are known as peptides
(joined by peptide bonds)
- Larger numbers of amino acids joined together are known as polypeptides
- Polypeptides which have a biological function are known as proteins- polypeptides
and proteins are terms used relatively interchangeably
× A protein consists of one or more polypeptides, each folded into a specific three-
dimensional structure- this allows it to interact with other molecules
× There are 20 different amino acids that cells use to build their proteins (great variety)
× Amino acids- all share a common structure, a central (alpha, a) carbon atom attached to
- An amino group (NH3+)
- A carboxyl group (COO)
- A hydrogen atom (H)
- A variable side chain (“R” or “R” group- these different groups give the protein
different properties)
× The 20 amino acids can be grouped according to the properties of their side chains
× Synthesis and breakdown of polymers
- Synthesis of a polymer involves loss of water (dehydration) to form a new covalent
bond
- Polymer breakdown involves addition of water (hydrolysis) to split a covalent bond
- Both these reactions are catalysed by enzymes
× Synthesis of proteins
- Amino acids are linked together by peptide bonds to form a polypeptide chain
- Proteins consist of a backbone of peptide bonds- side chains project from this
backbone
- The polypeptide chain folds to give the protein its specific 3D structure which
ultimately determines the function of the protein
- Because these polypeptides have an amino acid on one side, and a carboxyl group
on the other side, they have polarity (or direction)- the amino acid (N-terminus)
comes first, and we add to the carboxyl end (C-terminus)
Document Summary
Briefly describe the general structural features of proteins (chapter 5, concept 5. 4) Proteins are polymers of amino acid monomers- these polymers are commonly called polypeptides. When small numbers of amino acids join together, they are known as peptides (joined by peptide bonds) Larger numbers of amino acids joined together are known as polypeptides. Polypeptides which have a biological function are known as proteins- polypeptides and proteins are terms used relatively interchangeably. A protein consists of one or more polypeptides, each folded into a specific three- dimensional structure- this allows it to interact with other molecules. There are 20 different amino acids that cells use to build their proteins (great variety) Amino acids- all share a common structure, a central (alpha, a) carbon atom attached to. A variable side chain ( r or r group- these different groups give the protein different properties) The 20 amino acids can be grouped according to the properties of their side chains.
