Project Materials

CHARACTERIZATION OF ARGINASE FROM THE LIVER OF MANGO TILAPIA (Sarotherodongalilaeus)

ABSTRACT

The detoxifying enzyme arginase catalyses the hydrolysis of arginine into ornithine and urea, which is the final stage of the urea cycle, which is how the body gets rid of toxic ammonia. The purpose of this study was to identify the liver arginase characteristics of Sarotherodongalilaeus, or mango tilapia, in the Opa River in Osun State. Centrifugation and homogenisation at 4000 rev/min were used to separate the enzyme “arginase” from the liver of mango tilapia. The Bradford method was used to determine the protein concentration, and the Kaysen and Strecker method was used to determine the arginase assay. According to the kinetic analysis, the liver arginase Km value of mango tilapia is 0.2M, and its Vmax value is 166.7µmol/ml/min. The best temperature for mango tilapia liver arginase, according to tests on the influence of temperature on arginase activity, is 50°C, where the activity is 63.44µmol/ml/min. The optimal pH is 8.0 at an activity of 165.1µmol/ml/min, according to research on the effect of pH. Additionally, an inhibition research was conducted, and it was found that zinc (51.5±4.27) and calcium (51.4±1.13) strongly inhibit arginase, whereas sodium, magnesium, and mercury have little to no inhibitory impact. The results also indicate that urea has a less inhibitory impact on arginase than citrate (20.8±4.67), glutathione (28.6±2.53), and ethylenediamineacetic acid (EDTA). With residual activity of 107.2%, 86.6%, 73.4%, 62.1%, and 58.7%, respectively, the results of the study on the impact of amino acids on enzyme activity indicate that the liver arginase of mango tilapia is arranged as follows: arginine > valine > aspartate > cysteine > lysine. According to Mora J et al.’s categorisation (1965), mango tilapia liver arginase is a member of the ureotelic class of arginases. Its aVmax value is 166.7µmol/ml/min, and its Km value is 0.2M.

CHAPTER ONE

INTRODUCTION

THE BACKGROUND OF THE STUDY

The urea cycle, which is in charge of removing nitrogenous waste from organisms, depends heavily on the essential enzyme arginase. It helps control arginine metabolism and the general nitrogen balance in a variety of organisms by catalysing the hydrolysis of arginine to ornithine and urea.

Clarifying the physiological functions of arginase enzymes from various species and investigating possible uses in a variety of domains require an understanding of their traits and attributes.

The Mango Tilapia (Sarotherodon galilaeus) is a freshwater fish species widely dispersed in Africa and noted for its commercial and nutritional importance. It inhabits various freshwater environments, including rivers, lakes, and swamps, and has adapted to different ecological conditions.

The liver is a metabolically active organ that plays a critical role in the detoxification and regulation of several biochemical processes, including nitrogen metabolism.

Despite the economic and ecological importance of Mango Tilapia, insufficient information is available regarding the characterization of enzymes associated in nitrogen metabolism, such as arginase, in this species.

Characterizing arginase from the liver of Mango Tilapia can provide insights into its enzymatic characteristics, substrate specificity, and putative regulatory mechanisms.

Characterization studies on arginase have been undertaken in numerous creatures, including mammals, birds, and other fish species, revealing differences in enzyme characteristics, tissue distribution, and regulatory mechanisms. The importance of comprehending the functional diversity of arginase enzymes across species has been emphasised by these investigations.

The current investigation attempts to describe the enzymatic activity, ideal conditions for activity, kinetic parameters, and impact of metal ions and inhibitors on the function of arginase derived from the liver of mango tilapia.

This study will advance our understanding of arginine metabolism in Mango Tilapia and its possible applications in aquaculture, health, and biotechnology by clarifying the characteristics of arginase in this species.