Project Materials

PURIFICATION AND CHARACTERIZATION OF RHODANESE FROM THE LIVER OF MANGO TILAPIA (Sarotherodon galilaeus) FOUND IN ERINLE RESERVOIR, SOUTH WEST, NIGERIA

ABSTRACT

Rhodanese, a ubiquitous enzyme, catalyses cyanide detoxification via the sulphuration process. Cyanide is a very poisonous chemical, and inadequate detoxification can limit respiration, ATP synthesis and its related processes, liver damage, and necrosis in aquatic creatures. Given the fish’s habitat, which is a reservoir, it is exposed to hazardous compounds and waste products such as cyanide and ammonia.

If fish can survive after being exposed to cyanide, we can presume that they have a cyanide-detoxifying mechanism and enzyme. Rhodanese was isolated and characterised from Sarotherodon galilaeus liver using ammonium sulphate precipitation and Reactive blue-2-agarose affinity chromatography.

The enzyme’s specific activity was determined to be 121RU per milligramme of protein. The enzyme’s optimum pH was discovered to be 8.5, with an optimum temperature of 40°C. The Km values for the substrates KCN and Na2S2O3 were 40mM and 11.76mM, respectively.

Studies on the influence of cations on the enzyme revealed that Mn2+ and Ni2+ had no effect on its activity; however, 0.01mM concentrations of Mg2+, Ca2+, and Zn2+ significantly inhibited the enzyme.

The study’s findings revealed that the enzyme rhodanese is active in the fish liver, implying that the organism has a cyanide-detoxifying system.

Thus, chronic cyanide exposure will overwhelm the detoxifying process, resulting in liver damage and respiratory suppression. Furthermore, at very high temperatures (above 70°C) and pH, the enzyme is inactivated.