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Structural Proteins

Structural Proteins. Presented by: Andrew and Briana. Structural Protein Overview. Largest class of proteins (75% of the dry weight in humans) Generally add stiffness and rigidity to fluid biological components Commonly very fibrous

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Structural Proteins

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  1. Structural Proteins Presented by: Andrew and Briana

  2. Structural Protein Overview • Largest class of proteins (75% of the dry weight in humans) • Generally add stiffness and rigidity to fluid biological components • Commonly very fibrous • Provide support for both large structures and microscopic structures Microfilaments

  3. Role in Living Things • Keratin • Form strong supercoils • Protective function such as hair, nails, scales, feathers, and beaks • Elastin • Forms connective tissue (allows for stretching) • Tendons, ligaments, skin flexibility, lungs, arteries • Myosin • Role in muscle movement such as hydrolysis of ATP • Fibroin • Insoluble • Parallel sheets form silk used by insects and spiders

  4. More Roles in Organisms • Microtubules • Protein = Tubulin • Cytoskeleton, cellular movement, mitotic spindle • Microfilaments • Protein = Actin • Cytoskeleton, muscle contraction, organelle movement • Intermediate Filaments • Protein = Keratin • Cytoskeleton • Not involved directly in movement

  5. How do they function? • Formation of fibers and filaments contribute to structural strength of proteins • Movement and re-adjustment such as actin or elastin require ATP • Other vitamins such as vitamin C are required for synthesis Polymerization ATP Dependent

  6. Shape and Function • Rigidity of Proteins • Antiparallel chains form super coils • Hardened by hydrogen bonding and disulfide bridges • Flexibility of Proteins • Solubility allows for globular proteins such as tubulin and actin to form into strands • Lateral imperfect helix allows for elongation • Transportation Ability • Polarization allows for transportation of molecules • One negative and one positive end in the structure Dissolve/Polymerize F-Actin Actin

  7. Synthesis of Proteins • Message sent to cell and genetic process begins • Formation of mRNA (Units of 3)

  8. Synthesis of Proteins Cont. • Enters the cytoplasm • Binds to a ribosome

  9. Synthesis of Proteins Cont. • tRNA brings the amino acid to the corresponding code on mRNA • tRNA continues coming until chain is complete (peptide bonds)

  10. Synthesis Miscellaneous • Protein synthesis inhibitors such as the toxin ricin stops the production of protein • Disruptions in translation can lead to mutations and a change in function (1 in 10,000) • Example of such mutation is sickle cell (hemoglobin) • Disruption of protein manufacture can be disastrous

  11. Specific Example: Collagen • The most abundant protein in mammals (25-35%) • Plays a large role in body structure through ligaments and tendons (holds bones and muscles together) • Vital for skin flexibility • Found in stiffer forms such as bone or cartilage

  12. Collagen Structure • 3 alpha peptide strands bonded together • Forms a super helix or 3 part coil • Glycine accounts for 1/3 of the structure to repeated pattern • No R-Group allows for closer connection among helixes, so hydrogen bonding and linking is facilitated • Formation of bundles impact function such as bone vs. ligaments (parallel or unparalleled) Collagen Type 1 Helix

  13. Collagen Genetics • Partial amino sequence: mhpglwlllvtlclteelaaageksygkpcggqdcsgscqcfpekgargrpgpigiqgpt(repeat of g) • Similar to: • Collagen alpha-6(IV) chain, partial [Macacamulatta] 96% • Collagen alpha-6(IV) chain, partial [Macacafascicularis] 96% • Many others predicted relatedness to primates • Indicated a possible conserved gene which shows that many animals may have had similar functional needs and the protein provided similar adaptive advantages

  14. Collagen Disorders • Non-Genetically Related • Osteoporosis, from old age, leads to inflexibility in joints, thinner skin, and weaker bones • Genetically Related • Osteogenesisimperfecta – Mutation leads to weak bones and irregular connective tissue • Ehler-Danlos Syndrome – Varying mutations and effects such as rupture of arteries or deformed connective tissue Impact of Osteogenesisimperfecta EDS Symptoms

  15. In-Depth Disorder: Scurvy • Cause: • Hydroxylation of lysines and prolines is a step that requires vitamin C as a cofactor. In scurvy, the lack of hydroxylation of prolines and lysines causes a looser triple helix (which is formed by 3 alpha peptides) • Symptoms: • Spots on skin • Spongy gums • Loss of teeth • Pain in joints/Overall weakness • Proposed Drug: • Target protein synthesis • A Vitamin C tablet that will provide necessary amounts of vitamins so that collagen can form • Treatment applies to animals such as primates that cannot form their own vitamin C. Other animals produce their own Vitamin C.

  16. From Andrew and Briana Thanks for listening

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