KIN346 Lecture 9: Protein
5 Apr 2017
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What are proteins: protein, greek derivative protos , meaning of prime importance , organic molecules, 2nd most abundant component of plants and animals (2nd to water) Food sources: animal-based food (meat, fish, milk, plant sources: dried beans, peas, nuts, seeds, some vegetables. How many amino acids: 20 (same 20 in all animals), 9 are essential, 11 are non-essential. Essential amino acid: refers to an amino acid that the body cannot synthesize . must be ingested. Non-essential amino acid: refers to an amino acid that the body can synthesize. Examples: tyrosine is made from phenylalanine, cysteine is made from methionine. Most natural polypeptides = 50-200 amino acids called a protein. Primary structure: primary structure, secondary structure, alpha helices, beta pleated sheets, tertiary structure, quaternary structure, >= 2 tertiary structures. Protein denaturation: loss of protein shape . energy input overcomes dissociation energy of chemical bonds. 126: factors: ph, heat, alcohol, oxidation, mechanical agitation.
