BIOL 540 Study Guide - Quiz Guide: Dimethylallyl Pyrophosphate, Hmg-Coa Reductase, De Novo Synthesis
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1. ) acetoacetyl-coa thiolase: catalyze the condensation of two acetyl-coa molecules to form acetoacetyl-coa. Hmg-reductase: uses 2 molecules of nadph to hydrolyze the thioester linkage of hmg-coa and reduces hmg to mevalonate: first committed step of cholesterol biosynthesis, vmax will be lowered, makes it a better substrate for protein degradation. 2 molecules of farnesyl pyrophosphate are joined by squalene synthase using nadph to form squalene (30-carbon molecule) Squalene is cyclized by squalene oxidocyclase to form lanosterol: takes and add one oxygen from molecular oxygen to squalene. A series of redox reaction, typically using cyp450 enzymes, to convert lanosterol to cholesterol: lost of 3 different carbons; a carboxylic acid group and two co2, goes from 30 carbons to final product cholesterol with 27-carbons. Vldl: carries cholesterol and fat made in the liver to other tissues. Ldl: get cholesterols and fats to peripheral tissues, either from diet or liver: can mature from vldl. Hdl: send materials from peripheral tissues back to liver: ex.
