Facts about Glycolysis
The enzyme is activated by fructose 1,6-bisphosphate, an intermediate in glycolysis, driving the rate of glycolysis when more substrate is present.
A classical explanation holds that the local depletion of oxygen within the tumor is the cause of increased glycolysis in these cells.
The ultimate fate of the pyruvate and NADH produced in glycolysis depends upon the individual organism and the specific cellular conditions, most notably the presence or absence of oxygen.
Pyruvate kinase (PK) activity catalyzes the final step of glycolysis, in which pyruvate is formed.
Glycolysis, through anaerobic respiration, is the main energy source in many prokaryotes, eukaryotic cells devoid of mitochondria (e.g., mature erythrocytes), and eukaryotic cells under low-oxygen conditions (e.g., heavily-exercising muscle or fermenting yeast).
The second half of glycolysis is known as the payoff phase; it is characterized by a net gain of the energy-rich molecules ATP and NADH.
Hexokinase is inhibited by glucose-6-phosphate (G6P), the product it forms in the first step of glycolysis (an example of feedback inhibition).
The mechanism by which ATP molecules are generated in glycolysis is known as substrate-level phosphorylation: a phosphoryl group is transferred from a glycolytic intermediate to ADP by an enzyme called a kinase.
The first five steps of glycolysis (described in the table below) prepare glucose for breakdown by "trapping" it in the cell and destabilizing it, which requires an investment of 2 ATP.