During glycolysis, phosphofructokinase converts fructose 6-phosphate (F6P) into fructose 1,6-bisphosphate (F1,6BP), as shown below. Aldolase then converts F1,6BP into glyceraldehyde 3-phosphate (GAP) and dihydroxyacetone phosphate (DHAP). Respectively, phosphofructokinase and aldolase are examples of:

Question

During glycolysis, phosphofructokinase converts fructose 6-phosphate (F6P) into fructose 1,6-bisphosphate (F1,6BP), as shown below.  Aldolase then converts F1,6BP into glyceraldehyde 3-phosphate (GAP) and dihydroxyacetone phosphate (DHAP).  Respectively, phosphofructokinase and aldolase are examples of:

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11ecba2d_0e74_251d_a3bf_3561c27e50ef_MD0008_00 Enzymes are classified into one of six categories based on their mechanism of catalysis. Transferases move a chemical group from one molecule to another. Kinases are a type of transferase that either move a phosphate group from ATP to a substrate to form ADP and phosphorylated substrate, or from a substrate to ADP to form ATP. Phosphofructokinase transfers a phosphate from ATP to fructose 6-phosphate (F6P), forming ADP and fructose 1,6-bisphosphate (F1,6BP). Therefore, phosphofructokinase is a transferase. Lyases either form two molecules by breaking a bond within one molecule or they combine two molecules into one. To form bonds between reactant molecules, lyases add groups to a double bond. In the reverse reaction, they break a single bond in a reactant and generate a new double bond in the products. Aldolase splits F1,6BP into glyceraldehyde 3-phosphate (GAP) and dihydroxyacetone phosphate (DHAP) by forming a new C=O double bond. Therefore, aldolase is a lyase. (Choices A and C) Isomerases change the positions of functional groups within a single molecule, and hydrolases break bonds by adding water to them. Phosphofructokinase and aldolase transfer functional groups between molecules and break bonds by creating new double bonds, respectively. Ligases use the energy from ATP hydrolysis to combine two molecules into one. (Choice D) Oxidoreductases participate in redox reactions by transferring electrons from one molecule to another, and usually require NAD(P)H or FADH₂ as a substrate or a product. Neither phosphofructokinase nor aldolase catalyze redox reactions. Educational objective: Enzymes are classified based on their mechanism of catalysis. Oxidoreductases move electrons; transferases move functional groups between molecules; hydrolases break bonds by adding water, and lyases break bonds by forming a double bond elsewhere; isomerases move functional groups within a molecule; and ligases join molecules together using ATP as an energy source.

During Glycolysis, Phosphofructokinase Converts Fructose 6-Phosphate (F6P) into Fructose 1,6-Bisphosphate