The application of native enzymes may not be economical owing to the stability factor. A smaller protein molecule may be less susceptible to external stresses. Haloalkane dehalogenases (HLDs) that act on toxic haloalkanes may be incorporated as bioreceptors to detect haloalkane contaminants. Therefore, this study aims to develop mini proteins of HLD as an alternative bioreceptor which was able to withstand extreme conditions. Initially, the mini proteins were designed through computer modeling. Based on the results, five designed mini proteins were deemed to be viable stable mini proteins. They were then validated through experimental study. The smallest mini protein (model 5) was chosen for subsequent analysis as it was expressed in soluble form. No dehalogenase activity was detected, thus the specific binding interaction of between 1,3-dibromopropane with mini protein was investigated using isothermal titration calorimetry. Higher binding affinity between 1,3-dibromopropane and mini protein was obtained than the native. Thermal stability study with circular dichroism had proven that the mini protein possessed two times higher Tm value at 83.73 °C than the native at 43.97 °C. In conclusion, a stable mini protein was successfully designed and may be used as bioreceptors in the haloalkane sensor that is suitable for industrial application.
A Boer-Kajang cross male goat was presented to the Veterinary Hospital, University Malaysia Kelantan with a history of dysuria, hematuria and restlessness. The goat was intensively managed (confined to the pen) and fed with only palm kernel cake for the last three months. Physical examination revealed that the goat was dull, depressed, having an inflamed penis and prepuce with blood stained urine dripping from the penis. The differential diagnoses were obstructive urolithiasis, urinary tract infection and balanoposthitis. Based on the history, clinical signs, physical examination, urinalysis, ultrasonagraphy and feed analysis, the goat was diagnosed with obstructive urolithiasis and balanoposthitis. Treatment was instituted by amputation of the urethral process and retrograde urohydropulsion to relieve the blockade. Sulfadiazine-trimethoprim (Norodine(®)24) 15mg/kg, I.M; flunixin meglumine 2.2mg/kg, I.M; vitamin B complex 1ml/10kg, I.M and ammonium chloride 300mg/kg orally were administered. The goat responded well to treatment and was recovering well during a follow up visit.