BIO270 lec 3-6.docx - Allosteric and covalent regulation a...

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Allosteric and covalent regulation a) Competitive inhibition : By molecules not directly involved in catalysis can affect enzyme kinetics - Molecule not directly involve in rx. Competes with substrate for active site - Change Km - No change in conformation of enzyme b) Allosteric activation , when molecule bind to enzyme at site separate from active site --? Change conformtioan of E,  highly affinity for S - Allosteric regulator Bind to site not active site, change conformtiona E  change how E bnd to substrate  change Km , can affect Vmax , reach diff Vmax due to conf of E that affinity fr S Block the active site: does not max affect Vmax Alter the three- dimensional shape of the enzyme: may affect Vmax or K m c)Covalent activation : depend on what kinase does . - Kinase that phoaphorylate E, change conformation of E, P is very negative change distribution of charge of covalent bond of E, change affinity  phosphorylate lead activation of E, unphosphorylated repress of E, (reversible) Energy Storage – from nutrients Cells store energy in two main forms: Reducing energy : molecule has e- pass on , can be oxidized. High energy molecules : ATP stored in cell • Ultimately, serve as the energy currency of the cell = endo, exo • Act as substrates and products for hundreds of enzymes • Provide energetic support for many cellular processes Reducing Energy Reducing equivalents – chemical species that transfer an electron(s) in redox reactions Example: NADH, NADPH, FADH 2 , FMNH 2 examples can be reucued , carry high energy , transfer them to cell to reduce other molecule called as oxidoreductase , most are dehydrogenase Oxidoreductases – enzymes that transfer reducing equivalents between reduced (energy-rich) and oxidized (energy-poor) molecules Example: lactate dehydrogenase - Lactate is crucial in glycolysis bc, can remove NADH and pyruvate from cyto. Endo rxn Redox status – reducing energy within a cell reduced form/oxidized form if this ratio is high  have high reducing E within cell Example: [NADH/NAD + ] High if cell is rich in reducing energy Can be used to drive other reactions High Energy Molecules , phosphoanhydrogen bond btw 2 nd and 3 rd P, high Energy Energy can be “stored” in covalent bonds Energy is released when bonds are hydrolyzed = exergonic ATP is the most versatile “high energy” molecule , not stored in cell a lot bc involve in many rxn. Creatinephospho kinase transfer P to ATP, phosphocreatine is stored in high concentration in muscle, when ATP level drop, donate P to ADP to produce ATP Macromolecule synthesis Transport etc. Biomolecules Four main types: Proteins Carbohydrates Lipids Nucleic acids
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Proteins Contribute to cell structure and function Mediate all cellular processes (e.g. enzymes) Have complex 3D structure; coded in DNA Polymers of amino acids Amino acids – amino group (–NH 2 ) and carboxylic acid group (–COOH) Distinguished by R-groups: nonpolar (hydrophobic)
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