What is they, what makes them etc Proteins What is they, what makes them etc

Proteins are polymers In other words they are lots and lots of monomers This is different than Carbohydrates and Lipids because the monomers are all very different and this leads to variation in behaviour and structure All the variation is due to that R group – is R on the periodic table?

Peptide to Di peptide to polypeptide Simple – forming the peptide bond It is a condensation reaction – can you show me how two Gylcine molecules could bond? No peaking This is Glycine Now try the questions on page 62

Protein Structure Primary – the polypeptide chain – can you explain how this is made – on whiteboards Secondary – Alpha Helix or Beta Pleated sheet – structure is maintained by interactions between CO and NH groups Which if the secondary is made depends on the R groups so the primary structure – way to complicated to do here

Tertiary Structure Made possible due to Ionic bonds Disulphide Bridges Hydrophobic Hydrophilic interactions Hydrogen bonds

All the different groups of amino acid lead to interactions Ionic – simple positive to negative R groups Di-Sulfide bridges – between sulfur atoms Hydrophobic and Hydrophilic regions – hydrophobic groups stick together (usually in the centre of globular proteins and the hydrophilic regions get pushed to the outside Hydrogen bonds – Slight negative and positive charged groups attract (weak bonds)

Some questions What bonds hold together the primary structure? What defines the primary structure? What is the reaction that makes a peptide bond called? How many amino acids are coded for in your body? What does aromatic mean in biochemistry? What is the basic structural formula of an amino acid? What is the basic molecular formula of an amino acid?

Quaternary When more than one protein chain works with another one Examples Haemoglobin – four chains

Globular and Fibrous Globular are soluble Have a tertiary structure that readily impacts function The chains are folded into a spherical shape Common functions – enzymes, hormones, transport, immunity

Hormone Insulin Two chains an A and B chain All stuck together by Disufide bonds

More on Haemoglobin Special bits to consider here First it is a conjugated protein This means it has a non protein group stuck on This is called a prosthetic group in this case Iron containing Haem Group So simply Haemoglobin is the globular haem containing protein

Enzymes Loads of examples Two are amylase – to break down starch in your digestive system it is made from one polypeptide chain with both alpha and beta sections RuBisCo – possibly the most important enzyme in the world, and is massive, contains 8 small and 8 large subunits arranged as dimers (in 2). And as if befitting it’s important it is the most abundant protein on earth

Structural Proteins These do not dissolve (pretty handy) Tough and may be supple and stretchy Made of lots of parallel chains in long fibres or sheets Examples – Collagen, Myosin, Actin, keratin, elastin

Collagen Made of three helical polypeptides wound round each other like a rope Every third Amino Acid is a glycine which increases Hydrogen bonding this secures the strands tertiary structure It is found in all connective tissue on your body, the mineral content changes it’s behaviour – e.g more minerals = bone