Subjects

Biology

Biological molecules

Proteins

How Amino Acids Build Cool Proteins

Name: Knowunity
Brand: Knowunity

View

Bethan Jones

@bethanjones_jdhy

12 Followers

Top of the class Student

A comprehensive guide to protein structure and formation, detailing the complex molecular arrangements of amino acids and their various bonding mechanisms. The text explores how proteins are built from their basic building blocks to complex 3D structures.

Structure of amino acids in proteins forms the foundation of protein synthesis, starting with 20 different naturally occurring amino acids
Peptide bonds in protein synthesis connect amino acids through condensation reactions to form polypeptide chains
Tertiary and quaternary protein structures represent higher-order protein organization, with tertiary involving single chain folding and quaternary involving multiple chains
Protein stability depends on various bonds including hydrogen bonds, ionic bonds, and disulfide bridges
Denaturation can occur due to temperature and pH changes, affecting protein functionality

23/05/2023

Proteins
Proteins are polymers whose molecules are made from many amino acids.
examples = haemoglobin, enzymes, antibodies, collegen (bone+

View

Amino Acid Types and Peptide Bond Formation

Amino acids are classified based on their R groups, which can be simple, hydroxyl, sulphur-containing, cyclic, basic, acidic, or ringed. This diversity allows for the creation of proteins with a wide range of properties and functions.

Vocabulary: Peptide bond - A covalent bond formed between the carboxyl group of one amino acid and the amino group of another, resulting in the release of a water molecule.

The formation of polypeptides occurs through condensation reactions, where amino acids join together, releasing water molecules in the process. This reaction can continue, forming longer chains that eventually become proteins.

Example: Lysine, an amino acid with a basic R group, has a side chain ending in an NH3+ group, which contributes to its ability to form ionic bonds within proteins.

Highlight: The sequence and types of amino acids in a polypeptide chain determine the protein's primary structure, which is crucial for its final three-dimensional shape and function.

View

Protein Structure Levels

Proteins exhibit four levels of structure, each building upon the previous:

Primary Structure: The sequence of amino acids in the polypeptide chain.
Secondary Structure: Regular patterns formed by hydrogen bonding between amino acids, such as alpha helices and beta sheets.
Tertiary and quaternary protein structures: The three-dimensional folding of the entire polypeptide chain and the arrangement of multiple polypeptide subunits, respectively.

Definition: Protein sequencing - The process of determining the primary structure of a protein by identifying the order of its amino acids.

Example: The alpha helix is a common secondary structure where the polypeptide chain twists into a regular spiral, stabilized by hydrogen bonds between amino acids.

Highlight: The tertiary structure is responsible for a protein's unique properties and functions, held together by various bonds between the R groups of amino acids.

View

Bonds in Protein Structure

Various types of bonds and interactions contribute to maintaining protein structure:

Hydrogen bonds: Weak interactions between partially charged atoms.
Ionic bonds: Strong interactions between oppositely charged groups.
Disulphide bonds: Strong covalent bonds between cysteine amino acids.
Hydrophobic interactions: Attractions between non-polar R groups.
Van der Waals forces: Weak attractions between atoms in close proximity.

Example: Hemoglobin, the oxygen-carrying protein in red blood cells, exhibits quaternary structure with four polypeptide chains arranged in a tetrahedral shape.

Highlight: The final three-dimensional shape of a protein can be classified as globular (compact and soluble) or fibrous (long, insoluble, and tough).

View

Protein Structure Comparison

Globular and fibrous proteins have distinct structural characteristics:

Globular Proteins:

Compact, spherical shape
Often soluble in water
Examples include enzymes and hemoglobin

Fibrous Proteins:

Long, parallel chains with cross-linkages
Insoluble and tough
Relatively unaffected by temperature or pH changes
Examples include collagen and keratin

Example: Collagen, a fibrous protein, consists of three identical polypeptide chains, while hemoglobin, a globular protein, has four different polypeptide subunits.

Highlight: The highest level of structure in collagen is secondary, whereas hemoglobin exhibits quaternary structure.

View

Protein Denaturation

Denaturation is the process by which a protein's structure is altered, often resulting in loss of function:

High temperatures can break hydrogen bonds, causing globular proteins to unfold and become insoluble.
Extreme pH levels can disrupt ionic bonds by altering the charges on R groups.

Definition: Denaturation - The alteration of a protein's structure, often leading to loss of its biological function.

Highlight: Protein structure relies heavily on the strong ionic bonds between positively and negatively charged R groups found on amino acids.

Understanding protein structure and denaturation is crucial for many biological processes and has important implications in fields such as medicine and biotechnology.

View

Page 7: Protein Denaturation

The final page discusses protein denaturation and its causes.

Definition: Denaturation is the process where protein structure is disrupted by breaking stabilizing bonds.

Highlight: Both high temperature and extreme pH can cause protein denaturation.

Example: Denaturation in globular proteins leads to unfolding and loss of solubility.

View

Amino Acid Structure and Protein Formation

The foundation of proteins lies in the structure of amino acids. Each amino acid consists of a central carbon atom bonded to an amino group, a carboxyl group, a hydrogen atom, and a variable R group. This R group determines the specific properties of each amino acid.

Vocabulary: Amphoteric - Capable of resisting changes in pH, a characteristic of proteins due to their amino acid composition.

Proteins are formed through condensation reactions between amino acids, creating peptide bonds. This process results in the formation of polypeptides, which can further combine to create complex protein structures.

Example: Glycine, the simplest amino acid, has a hydrogen atom as its R group, while alanine has a methyl group (CH3).

Highlight: There are 20 different naturally occurring amino acids found in proteins, each with a unique R group that contributes to the protein's overall structure and function.