Chem Chapter 21 Final - Categories of Amino Acids, Levels of Protein Structure, and Protein Properties

What are the categories of amino acids?

Nonpolar

Polar Neutral

Polar Acidic

Polar Basic

Nonpolar

Hydrophobic side chains

Polar Neutral

Polar side chains without charge

Polar Acidic

Polar side chains with a carboxylic acid group

Polar Basic

Polar side chains that can gain protons (basic)

What are the nonpolar amino acids?

Glycine (Gly)

Alanine (Ala)

Valine (Val)

Leucine (Leu)

Isoleucine (Ile)

Proline (Pro)

Phenylalanine (Phe)

Methionine (Met)

Tryptophan (Trp)

What are the polar neutral amino acids?

Serine (Ser)

Cysteine (Cys)

Threonine (Thr)

Tyrosine (Tyr)

Asparagine (Asn)

Glutamine (Gln)

What are the polar acidic amino acids?

Aspartic Acid (Asp)

Glutamic Acid (Glu)

What are the polar basic amino acids?

Lysine (Lys)

Arginine (Arg)

Histidine (His)

What are the four levels of protein structure?

Primary

Secondary

Tertiary

Quaternary

Primary Structure

The sequence of amino acids in a polypeptide chain

Determines the protein's overall structure and function

Secondary Structure

Local folding patterns, such as alpha helices and beta pleated sheets, stabilized by hydrogen bonds

Tertiary Structure

The overall 3D shape of a single polypeptide, stabilized by interactions between side chains (hydrogen bonds, ionic bonds, hydrophobic interactions, disulfide bonds)

Quaternary Structure

The association of two or more polypeptide chains into a functional protein

Held together by similar interactions as in tertiary structure

What are the properties of conjugated proteins?

Contain non-protein components (prosthetic groups) that are essential for their function

Lipoproteins (conjugated proteins)

Proteins with lipid components

Glycoproteins (conjugated proteins)

Proteins with carbohydrate components

Metalloproteins (conjugated proteins)

Proteins with metal ions

Nucleoproteins (conjugated proteins)

Proteins with nucleic acid components

What is denaturation in proteins?

Denaturation is the disruption of a protein’s secondary, tertiary, or quaternary structure without breaking the peptide bonds

What causes denaturation?

Heat

pH

Heavy metals

Alcohol denaturation leads to loss of protein function and stability

Properties of proteins?

Solubility

Enzyme activity

Specificity

Denaturation

Flexibility

Solubility

Can be soluble or insoluble in water, depending on their amino acid composition

Enzyme Activity

Many proteins are enzymes, catalyzing biochemical reactions

Specificity

Proteins have high specificity for their substrates and functions

Denaturation

Proteins can lose their functional shape under certain conditions, affecting their biological activity

Flexibility

Some proteins are flexible and can undergo conformational changes to carry out their functions

How are peptide bonds formed?

Formed between the amino group of one amino acid and the carboxyl group of another through a condensation reaction, releasing a water molecule

What happens to proteins in acidic conditions?

Proteins may denature or become positively charged

What happens to proteins in basic conditions?

In basic conditions (high pH), they may become negatively charged or denature due to changes in the protein's structure