proteins (polymers of amino acids). 20 amino acids grouped by properties of their side chains –...

PROTEINS(Polymers of Amino Acids)

20 Amino Acids

• Grouped by properties of their side chains– Non-polar (hydrophobic)– Polar (hydrophilic)– Acidic (-COOH grp)– Basic (-NH2)

• Polypeptide– Many amino acids linked together

Types of Proteins

• Structural – ligaments, hair, horns, webs• Storage (energy) – seeds, egg whites• Transportation – blood & Facillitated Diffusion• Regulation – hormones: insulin & testosterone• Movement/Reaction – reflex, contraction• Immunology – antigens & antibodies• Enzymes – speed up rxns (digestion)

DENATURATION

• Protein loses its shape & no longer function– More shape changes, greater impact on its ability

to function

• Causes:– Temperature– pH (toxic chemicals)– Radiation

• Example: Sickle Cell Anemia

MOLECULAR STRUCTURE

• PRIMARY– Sequence of amino acids

MOLECULAR STRUCTURESingle (point) mutations can cause problems

Normal hemoglobin: VAL – HIS – LEU – THR – PRO – GLU –

GLU

Sickle Cell Hemo.: VAL – HIS – LEU – THR – PRO – VAL

– GLU

MOLECULAR STRUCTURE

• SECONDARY– A.A. chain coil or fold due H-bonds– Alpha Helix: -- Pleated Sheets

MOLECULAR STRUCTURE• TERTIARY– 3-D shape– Globular – (round clusters – hemoglobin)– Fibrous – (long threads – collegen)

– Hydrophobic interaction – nonpolar sections of molecule clump to middle of protein away from any possible sources of water

MOLECULAR STRUCTURE

• QUATERNARY– Interaction of multiple polypeptide chains

ENZYMES

• Substrate – substance being broken down• Active site – area where substrate/enzyme

connect

• Induced Fit – slight change of shape as enzyme & substrate join

Affects on Reaction Rates

• Cofactors / coenzymes – an additional enzyme working on same substrate

• Competitive Inhibitors – block active site

Affects on Reaction Rates• Noncompetitive

Inhibitors – changes shape of the enzyme without attaching to the active site

• Allosteric regulation – attachment of another molecule which changes the shape of the enzyme

Metabolic Controls

• Feedback Inhibition – the

product of the reaction binds to the enzyme & prevents it

from doing its job. Avoid excess production

Metabolic Controls• Cooperativity – (form allosteric regulation)

when another molecule helps maintain shape of enzyme