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Amino Acids Proteins, and Enzymes

Amino Acids Proteins, and Enzymes. Types of Proteins Amino Acids The Peptide Bond. Types of Proteins. Type Examples Structural tendons, cartilage, hair, nails Contractile muscles Transport hemoglobin Storage milk Hormonal insulin, growth hormone Enzyme catalyzes reactions in cells

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Amino Acids Proteins, and Enzymes

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  1. Amino Acids Proteins, andEnzymes Types of Proteins Amino Acids The Peptide Bond

  2. Types of Proteins Type Examples • Structural tendons, cartilage, hair, nails • Contractile muscles • Transport hemoglobin • Storage milk • Hormonal insulin, growth hormone • Enzyme catalyzes reactions in cells • Protection immune response

  3. Amino Acids • Building blocks of proteins • Carboxylic acid group • Amino group • Side group R gives unique characteristics R side chain I H2H—C —COOH I H

  4. Examples of Amino Acids H I H2N—C —COOH I H glycine CH3 I H2N—C —COOH I H alanine

  5. Types of Amino Acids Nonpolar R = H, CH3, alkyl groups, aromatic O Polar ll R = –CH2OH, –CH2SH, –CH2C–NH2, (polar groups with –O-, -SH, -N-) Polar/Acidic R = –CH2COOH, or -COOH Polar/ Basic R = –CH2CH2NH2

  6. Learning Check AA1 Identify each as (1) polar or (2) nonpolar A. NH2–CH2–COOH (Glycine) CH3 | CH–OH | B. NH2–CH–COOH (Serine)

  7. Solution AA1 Identify each as (1) polar or (2) nonpolar A.(2) NH2–CH2–COOH (Glycine) CH3 | CH–OH | B. (1)NH2–CH–COOH (Serine)

  8. Essential Amino Acids • 10 amino acids not synthesized by the body • arg, his, ile, leu, lys, met, phe, thr, trp, val • Must obtain from the diet • All in diary products • 1 or more missing in grains and vegetables

  9. Amino Acids as Acids and Bases • Ionization of the –NH2 and the –COOH group • Zwitterion has both a + and – charge • Zwitterion is neutral overall + NH2–CH2–COOHH3N–CH2–COO– glycine Zwitterion of glycine

  10. pH and ionization H+ OH– + + H3N–CH2–COOHH3N–CH2–COO–H2N–CH2–COO– Positive ionzwitterionNegative ion Low pH neutral pH High pH

  11. Learning Check AA2 CH3 CH3 + H3N–CH–COOH H2N–CH2–COO– (1) (2) Select from the above structures A. Alanine in base. B. Alanine in acid.

  12. Solution AA2 CH3 CH3 + H3N–CH–COOH H2N–CH2–COO– (1) (2) Select from the above structures • (2) Alanine in base. • (1) Alanine in acid.

  13. The Peptide Bond Amide bond formed by the –COOH of an amino acid and the –NH2 of the next amino acid O CH3 + || + | NH3–CH2–COH + H3N–CH–COO– O CH3 + ||| NH3–CH2–C – N–CH–COO– | peptide bond H

  14. Peptides • Amino acids linked by amide (peptide) bonds Gly Lys Phe Arg Ser H2N- -COOH end Peptide bonds end Glycyllysylphenylalanylarginylserine

  15. Learning Check AA3 What are the possible tripeptides formed from one each of leucine, glycine, and alanine?

  16. Solution AA3 Tripeptides possible from one each of leucine, glycine, and alanine Leu-Gly-Ala Leu-Ala-Gly Ala-Leu-Gly Ala-Gly-Leu Gly-Ala-Leu Gly-Leu-Ala

  17. Learning Check AA4 Write the three-letter abbreviations for the following tetrapeptide:

  18. Solution AA4 Ala-Leu-Cys-Met

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