Protein Regulation Flashcards
What is allosteric regulation?
When external substances, such as substrate can prompt changes of an enzyme between a high affinity T state and a low affinity R state.
What are the two enzymes involved in the phosphorylation of proteins?
Protein kinases: transfer terminal phosphate of ATP to a protein.
Protein phosphotases: reverse effects of kinases, which the hydrolytic removal of a phosphate group.
How is proteolytic cleavage of proteins regulated?
Endogenous activators such as pancreatic trypsin inhibitor
What is a zymogen?
An inactive precursor to a hormone which can be activated by proteolytic cleavage.
What are the activators and inhibitors of phosphofructokinase?
Activators: AMP, fructose 2,6 bisphosphate
Inhibitors: ATP, citrate, h+
What is an enzyme cascade?
When enzymes activate molecules, one after the other and the number of molecules increases geometrically.
What is the enzyme activated at the end of the blood clotting cascade (and from what inactive precusor is it activated)?
Thrombin (activated from prothrombin)
What are the short term methods of regulating hormones?
Allosteric regulation, regulation by substrate and product concentration, as well as covalent modification.
How is trypsin activated?
Edniopeptidase cataysles the production of trypsinogen to trypsin.
What enzymes is trypsin involved in the activation of?
Activation of various spzymogens by protolytic cleavage, Chymotrypsinpgen to pie- chymotrpsin, proelastase to elastase, procarboxypeptidase to carboxypepetidase, prolipase to lipase
What is the action of thrombon at the end of the blood clotting cascade?
Cataylses the formation of fibrin from firbogen, protelyticaly cleaving n linked negatively charged peptidases allowing fibrin molecules to cross linked with one another.
What is an endgoenous inhibitor?
Inhibits protease activity.
What is an example of an endogenous inhibitor and how is it clinically relevant?
A1 antitrypsin, a 53 kda plasma protein which inhibits protases, and there is a deficiency in this in emphysema, so elastase digest the walls of the lungs.
What clotting factor is missing in Haemophilia?
VIII
How is blood clotting localised?
Calcium ions attach to receptors on damaged endothelial linings, and prothrombin attaches to this at the site of injury, which helps transform fibrogen into fibrinogen.
