麻省理工学院 生物材料课程 lecture 5 Protein-Surface Interactions.pdfVIP

3.051J/20.340J 1 Lecture 5: Protein-Surface Interactions Importance of Protein-Surface Interactions: • Modulate cell adhesion • Trigger the biological cascade resulting in foreign body response • Central to diagnostic assay/sensor device design performance • Initiate other bioadhesion: e.g., marine fouling, bacterial adhesion Fundamentals on Proteins: • Largest organic component of cells (~ 18 wt% /H2O =70%); extra- cellular matrix, and plasma (7wt% /H2O=90%). • Many thousands exist—each encoded from a gene in DNA. • Involved in all work of cells: ex, adhesion, migration, secretion, differentiation, proliferation and apoptosis (death). • May be soluble or insoluble in body fluids. Insoluble proteins—structural motility functions; can also mediate cell function (ex., via adhesion peptides) Soluble proteins—strongly control cell function via binding, adsorption, etc. • Occur in wide range of molecular weights. 3.051J/20.340J 2 “Peptides” (several amino acids): hormones, pharmacological reagents e.g., oxytocin: stimulates uterine contractions (9 a.a.) aspartame: NutraSweet (2 a.a.) “Polypeptides” (~10-100 amino acids): hormones, growth factors e.g., insulin: 2 polypeptide chains (30 21 a.a.) epidermal growth factor (45 a.a.) “Proteins” 100’s-1000’s of amino acids e.g., serum albumin (550 a.a.) apolip oprotein B: cholesterol transport agent (4536 a.a.) Protein Functions: • Structural/scaffold: components of the extracellular matrix (ECM) that physically supports cells e.g., collagen—fibrillar, imparts strength; elastin—elasticity to ligaments;