On the Radiation-induced Aggregates of Lactate Dehydrogenase

Summary

Radiolysis of lactate dehydrogenase under N₂ leads to the formation of aggregates which are enzymatically inactive. These aggregates were isolated by gel filtration. Incubation with sodium dodecylsulphate followed by gel filtration made it obvious that these aggregates consist of protein fragments held together by hydrophobic and electrostatic interactions. Disulphide bridges were found to be unimportant for stabilizing the aggregates. All isolated protein fragments were smaller than the sub-units of lactate hydrogenase, indicating peptide-chain breaking as a major reaction in the radiolysis of proteins and in the inactivation process of enzymes.