Protein Structure & Function 2022 PDF

Proteins General Info… Proteins are chains of amino acids (a.a) connected by peptide linkages a.a. determines the structure and function of the protein Structure of a typical amino acid: “R” group is different for each amino acid (20 possible R groups hence there...

Proteins General Info… Proteins are chains of amino acids (a.a) connected by peptide linkages a.a. determines the structure and function of the protein Structure of a typical amino acid: “R” group is different for each amino acid (20 possible R groups hence there are 20 diff. a.a.) Amino Group “N terminus” Carboxyl group “C terminus”  Amino Acids hydrophobic hydrophilic ▪ Proteins are often amphiphilic because they are made of both non-polar and polar amnio acids. 9 amino acids are essential (body cannot make them, ∴ they must be in the diet) Peptide Synthesis Peptide a peptide is a polymer of 2 or more amino acids Named for the number of amino acids they contain ❑ dipeptides have 2, tripeptides have 3 ❑ oligopeptides have fewer than 10 to 15 ❑ polypeptides have more than 15 ❑ proteins have more than 100 Dehydration synthesis creates a peptide bond that joins amino acids Protein Structures ▪ Proteins fold to make 3D structures. ▪ Their structure is divided into 4 levels: ◆ Primary (1°) structure ◆ Secondary (2°) structure ◆ Tertiary (3°) structure ◆ Quaternary (4°) structure  1° Protein Structure Protein Structures Linear sequence of amino acids held together by peptide bonds. Slight change in sequence can change the structure and function of the protein (i.e. sickle cell). 2° Protein Structure a.a. chain coils to make an α-helix or folds to make a β-pleated sheet. Folding is caused by H bonds that form between “R” groups. 3° Protein Structure Folding of 2° polypeptide due to interaction between R groups and surrounding water. R groups form H bonds, disulfide bridges, ionic bonds & hydrophobic interactions. 4° Protein Structure occurs when 1 or more polypeptide chains join; held together by hydrogen bonds (i.e. hemoglobin)  Sickle cell anemia Sickle cell anemia: 1 DNA letter changes 1 amino acid = serious disease Hemoglobin mutation: bends red blood cells out of shape & they clog your veins. Tertiary structure held together by… Examples of Quaternary Structure Protein Structure analogy Protein Denaturation Denaturation is the unfolding of a protein ❑ usually destroys the function of a protein ❑ occurs with extreme heat or pH ❑ often permanent Protein can resume shape under normal conditions if primary structure is maintained Breaking Proteins  Examples of Denaturation ❖ Curly hair becomes straight after a hot shower ❖ Perming hair breaks S-S bonds & then reforms them in new places ❖ High fevers are feared because they may stop proteins that are vital to survival from working ❖ Foods are pickled to stop enzymes in bacteria from working, preventing the food from going bad ❖ Heating meat to make it tender Conjugated Proteins A compound, such as hemoglobin, that is made up of a protein molecule and a non protein prosthetic group. Hemoglobin has 4 polypeptide chains, each chain has a complex iron containing ring called a heme moiety Function of Proteins Rate the function from most to least important Structural support Transportation Movement Membrane transport Catalysis Communication Recognition & Protection Dr. Marie Maynard Daly the first African-American woman to earn a doctorate degree in chemistry made significant contributions to the scientific community’s understanding of proteins, amino acids, and other macromolecular building Dr. Marie Maynard Daly (1921– 2003) was a professor of biochemistry at the Albert Einstein blocks. College of Medicine. She was dedicated to the recruitment and enrollment of minority students for graduate STEM programs.