C785 BIOCHEMISTRY NOTES (WESTERN GOVERNORS UNIVERSITY)

Amino acid structure Amino acid types • Hydrophobic: ending in CHs • Polar: ending OH, NH, or SH • Charged: ending in a charge • Flow Chart: Is there a charge? → Is there S, N, or O? → Hydrophobic Amino acid NO NO ↓ YES ↓ YES Charged amino acid Polar Amino Acid Charged amino acids • Charged amino acids form ionic bonds with other oppositely charged amino acids. • Other charges like H+ from pH or salts (charged particles) break up these bonds • Found on protein’s exterior Polar amino acids • End in NH, OH, or SH • SH: Disulfide bonds, disrupted by reducing agent • NH or OH: Hydrogen bonds, disrupted by pH or salt • Found on protein’s exterior Hydrophobic Amino acids • Ends in CH • Hydrophobic interactions • Disrupted by heat • Weak • Located inside protein to prevent exposure to cytoplasm Levels of protein structure: Primary • Bond forming the backbone of peptide chain • Backbone = everything but R groups • Formed by dehydration synthesis – water is removed • Broken by hydrolysis – water is added • Amino acid position refers to its place in line in the chain. For example, the Thr at 75 means that threonine is positioned at the 75th amino acid in line. Level of protein structure: Secondary • Formed by hydrogen bonds between Backbone atoms of amino acids • Alpha helix form between amino acids above and below