BIO 253 Lecture Notes - Lecture 3: Isoelectric Point, Zwitterion, Histidine
Document Summary
Sulfur in the cysteine amino acid versus the sulfur atom in the methionine amino acid r and. L and d are not comparing the priority but comparing the side chains of the hydrogen, carboxyl groups. Isoelectric point (pi): net charge of zero (at the zwitterion state??) Histidine: can be present in four different ionic forms where it is completely protonated. Reaction: to make the peptide bond (or the amine bond); amino terminal to the left and carboxyl group to the right. Peptides/oligopeptides: usually less than 30 amino acids and are usually have no structure to them and they sometimes occur naturally in the body such as hormones, antibodies and toxins. Proteins: around 80 amino acids; can be formed by multiple stretches of polypeptides and usually has structure and other components attached to it. Insulin: first polypeptide to be sequenced by sanger; it is a peptide and contains two polypeptide chains linked together by disulfide bonds.
