2. Amino acids are commonly classified as nonpolar or as polar, based on the pro
ID: 574788 • Letter: 2
Question
2. Amino acids are commonly classified as nonpolar or as polar, based on the properties of the side chain residues. Quantification of these properties is important for a variety of protein structure predictions, but they cannot readily be determined from the free amino acids themselves. Why are the properties of the side chains difficult to measure using the free amino acids in aqueous or nonpolar solvents? How might you quantitatively determine hydrophobicity of amino acid side chains? (40 points)Explanation / Answer
what are the properties of aminoacids ;
physical properties include ; melting point , solubility ,optical activity , isomerism ,
melting point ; they have high melting points as they decompose . there will be internal transfer of the hydrogen from carboxylic group and amino group to leave ion as positive and negative charge . this form of aminoacids are called zwitter ions .
solubility ; they are generally soluble in water and non soluble in organic non polar solvents . the extent of solubility depends on the nature of R group , as water is a polar solvent so aminoacids are mole soluble . the lack of solubility in non organic solvents is because as there is no attractions between the aminoacids and solvent therefore there is no energy is released to pull the ion lattice .
optical activityand isomerism ;
they form chiral compounds ,
they exhibhit isomerism forms steroisomers .based on the optical activity they form D and L amino acids . the alpha carbon atom is chiral carbon , L amino acids are present in proteins during the translation .
They Hydrophobicity Quantitative;
The side chains of the aminoacids will bring the hydrophobicity of the aminoacids . the carbon chain attached to alpha carbons . they can form the weak base or weak acids . the non polar aminoacids are hydrophobic . the hydrophobicity effect plays major role in folding the proteins .
Hydrophobic aminoacids include valine ,leucine ,isoleucine ,phenyalanine ,tryptophan .hydrophobic interactions are aessed from the partition coefficient in a chromatography between the interactions between imessible solvents and water . there will be generalized hydrophibic scale
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