L2 Proteins and their Structure

Primary structure

peptide bonds formed via a condensation reaction; determines how the protein will fold; difficult to break down

Secondary structure

local, repeating folding patterns stabilized by hydrogen bonds between backbone atoms; alpha-helix; beta-peated sheet; easy to break down from environment and adsorption

Tertiary structure

3D; look at during lowest energy shape due to protein dynamics causing shape change; formed from 4 types of R group interactions; easier to change and break

Quaternary structure

multiple polypeptide chains assembled into a functional complex containing monomer, dimer, trimer, and tetramer

Tertiary structure: Covalent disulfide bonds

cysteines; rigid and strong protein

Tertiary structure: Ionic interaction

positively charged side chains (lysine, arginine, and histidine) and negatively charged side chains (aspartic acid and glutamic acid); strong rigid proteins resistant to shape change

Tertiary structure: Hydrogen bonds

serine and tyrosine; weaker softer proteins

Tertiary structure: Hydrophobic interactions

nonpolar residue that cluster in the protein core, away from water (leucine, phenylalanine, tryptophan, and valine); weak and easy to break; lots of shape changes

Amino acid

organic compound containing amino and carboxyl groups; backbone of proteins

Side chain

The differentiating component of an amino acid affecting charge, polarity, and protein function

Condensation reaction

Forms the primary structure of a protein by combining the carboxyl and amino groups of two amino acids, and produces water as a subproduct

Peptide bonds

Covalent bonds linking amino acids together to form a polypeptide chain in a protein

Alpha helix

right-handed coil formed by the amino group forming a hydrogen bond with a carboxyl group; facilitated protein folding; creates functional domains; structural stability

Beta pleated sheet

beta strands connected laterally by hydrogen bonds; functional domains; structural stability

Disulfide bonds

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Protein subunit

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Protein conformation

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Proteases

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Denaturation

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Extracellular matrix

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Integrin

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Cell differentiation

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Cell proliferation

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Cell apoptosis

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Collagen

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Elastin

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Fibronectin

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RGD sequence

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Fibrinogen

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Thrombin

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Fibrin

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