Glycolysis or EMP Pathway in bio chemistry

GLYCOLYSIS or EMP PATHWAY

The term glycolysis has originated from the Greek words, glycos for sugar,and lysis for splitting.

The scheme of glycolysis was given by Gustav Embden, Otto Meyerhof, and J. Parnas, and is often referred to as the EMP pathway. It is common in both aerobic and anaerobic respiration and occur in the cytosol of all living cells.

In this process, glucose undergoes partial oxidation to form two molecules of pyruvic acid. Glucose and fructose are phosphorylated to give rise to glucose-6 phosphate by the activity of the enzyme hexokinase. This phosphorylated form of glucose then isomerises to produce fructose-6-phosphate. Subsequent steps of metabolism of glucose and fructose are same.

In glycolysis, a chain of ten reactions, under the control of different enzymes, takes place to produce pyruvate from glucose. ATP is utilised at two steps: first in the conversion of glucose into glucose 6-phosphate and second in the conversion of fructose 6-phosphate to fructose 1, 6-bisphosphate. The fructose 1, 6-bisphosphate is split into dihydroxyacetone phosphate and

3-phosphoglyceraldehyde (PGAL).

We find that there is one step where NADH + H+ is formed from NAD+; this is when 3-phosphoglyceraldehyde (PGAL) is converted to 1, 3-bisphosphoglycerate (BPGA). Two redox-equivalents are removed (in the form of two hydrogen atoms) from PGAL and transferred to a molecule of NAD+. PGAL is oxidised and with inorganic phosphate to get converted into BPGA. The conversion of BPGA to 3-phosphoglyceric acid (PGA), is also an energy yielding process; this energy is trapped by the formation of ATP.

Another ATP is synthesised during the conversion of PEP to pyruvic acid. Net result of glycolysis is 2pyruvic acid molecules, 02 molecules of H₂O, 02 molecules of ATP and 02 molecules of NADH+H⁺.

Diagrammatic explanation of glycolysis pathway