Protein Structure

Primary Structure The primary structure is the sequence of

amino acids, which is different for each protein.

Primary Structure The primary structure is the sequence of

amino acids, which is different for each protein.

The sequence determines the properties of the protein.

Primary Structure The primary structure is the sequence of

amino acids, which is different for each protein.

The sequence determines the properties of the protein.

The info for the sequence of amino acids in a polypeptide chain is stored in a gene.

Primary Structure The primary structure is the sequence of

amino acids, which is different for each protein.

The sequence determines the properties of the protein.

The info for the sequence of amino acids in a polypeptide chain is stored in a gene.

A gene can be defined as ‘that length of DNA that codes for a polypeptide’

Primary Structure When a mutation occurs in a gene, the

mutation usually results in an altered protein – resulting in either a non-functional protein or do nothing at all.

Primary Structure When a mutation occurs in a gene, the

mutation usually results in an altered protein – resulting in either a non-functional protein or do nothing at all.

Human proteins are made of 20 amino acids.

Primary Structure When a mutation occurs in a gene, the

mutation usually results in an altered protein – resulting in either a non-functional protein or do nothing at all.

Human proteins are made of 20 amino acids.

The number of possible different sequences of the 20 amino acids is vast.

Secondary structure The primary structure is bent/twisted to

form a helix or pleated sheet.

Secondary structure The primary structure is bent/twisted to

form a helix or pleated sheet. Pleated sheet – sections of polypeptide

chains run side by side.

Secondary structure The primary structure is bent/twisted to

form a helix or pleated sheet. Pleated sheet – sections of polypeptide

chains run side by side. The shapes are held in place by

hydrogen bonding between certain amino acids.

Tertiary Structure Globular proteins are further bent to

form a complex shape.

Tertiary Structure Globular proteins are further bent to

form a complex shape. This shape is both maintained by both

hydrogen and disulfur bonding between certain amino acids.

Tertiary Structure Globular proteins are further bent to

form a complex shape. This shape is both maintained by both

hydrogen and disulfur bonding between certain amino acids.

Quartenary Structure Some globular proteins are made of two

or more polypeptide chains held loosely together.

Quartenary Structure Some globular proteins are made of two

or more polypeptide chains held loosely together.

Eg – haemoglobin has four polypeptide chains

Chemical Activity Although globular proteins are large,

their chemical activity resides in a small part of the molecule – the active site in enzymes.

Chemical Activity Although globular proteins are large,

their chemical activity resides in a small part of the molecule – the active sit in enzymes.

The bonds maintaining the shape are weak, so temperature can denature the enzyme (lose it’s chemical/biological function)

Chemical Activity Although globular proteins are large, their

chemical activity resides in a small part of the molecule – the active sit in enzymes.

The bonds maintaining the shape are weak, so temperature can denature the enzyme (lose it’s chemical/biological function)

Enzymes are catalysts for chemical reactions of life – they temporarily combine with substances (the substrate), forming an enzyme-substrate complex.

Chemical Activity This bonding occurs at the active site –

slightly changing the shape to fit the substrate.

Chemical Activity This bonding occurs at the active site –

slightly changing the shape to fit the substrate.

This is possible because of the weak bonds.

Chemical Activity This bonding occurs at the active site –

slightly changing the shape to fit the substrate.

This is possible because of the weak bonds.

If an enzyme loses it’s shape because of denaturing, or through a mutation in the amino acid sequences, the active site can be lost so the enzyme can no longer catalyse the reaction.

Chemical Activity