BIO 4307 Chapter Notes - Chapter 3: Tryptophan, Hydrophile, Alanine
Document Summary
Amino acids are chiral or there may have a mirror images called the l and d isomer. Only l amino acids are constituents of proteins, why no one knows but pure l or. D amino acids are more soluble than a stable dl crystal. easier: all amino acids have at least two charged groups. Under physiological conditions and in a neutral solution aa exists as dipolar ions the amino group is protonated and the carboxyl group is deprotonated. In a more acidic solution the amino group and carboxylic group are protonated. Simplest example is glycine it has only one h atom as its side chain and it is achiral. Alanine has a methyl group as its side chain: more complex aa are valine, leucine and isoleucine. This is the driving force for the formation of the unique 3d structure of water-soluble proteins.
