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Lecture 14 Enzyme Regulation-BW

Amount of k how are i and f balanced feed forward

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Unformatted text preview: ] balanced? Feed forward - need both F and I - F stimulate e10 or I s timulate e5 3/8/13 MCB 2000 Lecture 14 Phosphorylation: an important covalent modification that modulates protein activity Phosphorylation Single trasnductino - adapation - end consequence - typically change in the covalent modifi cation of an enzyme that covalent modifi cation will efect the activity of the enzyme 3/8/13 MCB 2000 Lecture 14 Protein with hydroxyl grou p - phosphorlate a protien on a hydroxyl group phsophate donor - spilt ATP get ADP - inorganic phosphate - that will be bound to c ovalently to the hydoxyl group - enzyme that carries this our = kinases - specifi c involves a covalent bond - not going to fall apart - reversible by having an enzyme to r emove it (protein phsophastes) how does adding a phosphate alter the activity of an enzyme introducing a negative c harge - taken polar hydorxyl group and now put a charged phsophate - have c hange the nonvoalent interaction at that particular site. protein taht undergo this modifi cation - have multi phosphylating s ites - Kinases add phosphate to serine, threonine, tyrosine hydroxyl groups. Phosphatases remove the phosphate(s) added by the kinases. Both can be very specific for the proteins that they modify. 3/8/13 MCB 2000 Lecture 14 Phosphorylation / dephosphorylation rapidly alters the activity of an enzyme Changes in phosphorylation / dephosphorylation are initiated by some external signal (for example, a hormone or neurotransmitter) insulin gluoagon and epinephrine - lead to activation of kinsase which will phsophylate a protien - to start need a external s ignal to start it (light, neurotrasnmitter) the end result will always be change in the activity of a protien 3/8/13 MCB 2000 Lecture 14 Phosphorylation / dephosphorylation rapidly alters the activity of an enzyme Addition of a phosphate to a protein introduces negative charges disrupt or form electrostatic interactions can form hydrogen-bonds Addition of a phosphate to a protein is a covalent bond reversible through the action of phosphatases Activity may be increased or decreased effect is specific to the enzyme 3/8/13 MCB 2000 Lecture 14 Enzymes can be regulated by other covalent modifications on amino acids Argine as the acceptor - ADP ribose - adding phsophate small group and neg charge - when you add ADP ribos - introudce an aromatic ring, s ugar, hydroxyl group, phosphate - entire strucutre is large - modifi ty any of these amino acid (for example argiine- with that bulky group going to distrupt a lot of interaction - ikely going to alter the activity of a protein in a negative way - acetylation can happen on the R group of arg or lys - on the side chain - they mask the charge becuase both pos charge - that amino acid no longer going to be postiviely charge where is this going to be imporant? -the enzyme that adds the acetly group - actealtes - both for chemotherepy- cancer uncontroalble grow normally in human if you strech it 6 feet long - that...
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