بررسي اثرات جانبي آسپيرين بر ساختار و عملكرد آنزيم كاتالاز كبدي

Side effects of aspirin on the structure and function of liver catalase

ﺳﺎﺑﻘﻪ و ﻫﺪف: ﮐﺎﺗﺎﻻز آﻧﺰﯾﻤﯽ اﺳﺖ ﮐﻪ ﺗﺠﺰﯾﻪ ي H2O ﺑﻪ آب و اﮐﺴﯿﮋن ﻣﻮﻟﮑﻮﻟﯽ را ﮐﺎﺗﺎﻟﯿﺰ ﻣﯽ ﮐﻨﺪ. از ﺳـﻮ ي دﯾﮕـﺮ آﺳﭙﯿﺮﯾﻦ داروي ﺑﺴﯿﺎر ﻣﻬﻤﯽ اﺳﺖ ﮐﻪ ﺗﻮﺳﻂ ﺑﺴﯿﺎري از ﺑﯿﻤﺎران و در ﺳﻄﺢ ﺟﻬﺎﻧﯽ اﺳﺘﻔﺎده ﻣﯽ ﺷﻮد. اﻫﻤﯿﺖ اﯾﻦ آﻧـﺰﯾﻢ در دﻓﺎع آﻧﺘﯽ اﮐﺴﯿﺪان ﺑﺪن و ارﺗﺒﺎط اﯾﻦ آﻧﺰﯾﻢ ﮐﺒﺪي ﺑﺎ ﺑﯿﻤﺎري ﻫﺎﯾﯽ از ﻗﺒﯿﻞ دﯾﺎﺑﺖ ﻣﻮﺟﺐ ﺷﺪ ﺗﺎ در اﯾﻦ ﻣﻄﺎﻟﻌﻪ ﺗـﺎﺛﯿﺮ آﺳﭙﯿﺮﯾﻦ را ﮐﻪ ﻣﺤﻞ ﻣﺘﺎﺑﻮﻟﯿﺰه ﺷﺪن آن ﻣﺎﻧﻨﺪ ﺗﻤﺎﻣﯽ داروﻫﺎ در ﮐﺒﺪ ﻣﯽ ﺑﺎﺷﺪ ﺑﺮ ﻋﻤﻞ ﮐﺮد و ﺳﺎﺧﺘﺎر آﻧﺰﯾﻢ ﮐﺎﺗﺎﻻز ﮐﺒـﺪي ﻣﻮرد ﺑﺮرﺳﯽ ﻗﺮار ﮔﯿﺮد. ﻣﻮاد و روش ﻫﺎ: ﺑﻪ ﮐﻤﮏ ﺗﮑﻨﯿﮏ ﻫﺎي ﻃﯿﻒ ﺳﻨﺠﯽ ﻣﺮﺋﯽ- ﻣﺎوراء ﺑﻨﻔﺶ و ﻓﻠﻮﺋﻮرﺳﺎﻧﺲ در دو دﻣﺎي 25 و 37 درﺟـﻪ ﺳﺎﻧﺘﯽ ﮔﺮاد ﺗﻐﯿﯿﺮات در ﺳﺎﺧﺘﺎر و ﻋﻤﻞ ﮐﺮد ﮐﺎﺗﺎﻻز ﻣﻮرد ﺑﺮرﺳﯽ ﻗﺮار ﮔﺮﻓﺖ. ﯾﺎﻓﺘﻪ ﻫﺎ: ﺑﺎ اﺳﺘﻔﺎده از ﻣﻄﺎﻟﻌﺎت ﮐﯿﻨﺘﯿﮑﯽ و ﺑﺎ ﺗﻮﺟﻪ ﺑﻪ ﻧﻤﻮدار و ﻣﻌﺎدﻟﻪ ي ﻣﯿﮑﺎﺋﯾـﻠﯿﺲ-ﻣﻨـﺘﻦ ﻣﻘـﺪار Km آﻧـﺰ ﯾﻢ 40 ﻣﯿﻠﯽ ﻣﻮﻻر اﻧﺪازه ﮔﯿﺮي ﺷﺪ. ﻧﺘﺎﯾﺞ ﺑﻪ دﺳﺖ آﻣﺪه از اﯾﻦ ﻣﻄﺎﻟﻌﻪ ﻧﺸﺎن داد ﮐﻪ آﺳﭙﯿﺮﯾﻦ ﺑﺎﻋـﺚ اﯾﺠـﺎد ﺗﻐ ﯿﯿـ ﺮ در ﻓﻌﺎﻟﯿـﺖ آﻧﺰﯾﻢ ﻧﻤﯽ ﺷﻮد. ﻫﺮ ﭼﻨﺪ اﻓﺰودن آﺳﭙﯿﺮﯾﻦ ﺑﺎﻋﺚ ﮐﺎﻫﺶ ﺗﺪرﯾﺠﯽ در ﺷﺪت ﻧﺸﺮ ﻓﻠﻮﺋورﺳﺎﻧﺲ ﮐﺎﺗﺎﻻز ﺷﺪ. ﻋﻼوه ﺑﺮ آن ﺑـﺎ اﻓﺰاﯾﺶ دﻣﺎ ﻣﻘﺪار ﺛﺎﺑﺖ اﺗﺼﺎل دارو ﺑﻪ آﻧﺰﯾﻢ ﮐﺎﻫﺶ ﯾﺎﻓﺖ. ﻧﺘﯿﺠﻪ ﮔﯿﺮي: ﮐﺎﻫﺶ ﻣﺸﺎﻫﺪه ﺷﺪه در ﻧﺸﺮ ﻓﻠﻮﺋﻮرﺳﺎﻧﺲ ذاﺗﯽ ﮐﺎﺗﺎﻻز در اﯾﻦ ﻣﻄﺎﻟﻌﻪ ﺗﺤﺖ ﺗﺎﺛﯿﺮ ﻏﻠﻈﺖ ﻫﺎي اﻓﺰاﯾﺸﯽ آﺳﭙﯿﺮﯾﻦ ﻧﺸﺎن داد ﮐﻪ اﯾﻦ دارو ﺑﺎ ﺑﺎز ﮐﺮدن ﺳﺎﺧﺘﺎر ﺳﻪ ﺑﻌﺪي ﮐﺎﺗﺎﻻز ﺑﻪ ﻋﻨﻮان ﯾﮏ ﺧﺎﻣﻮش ﮐﻨﻨﺪه ﻋﻤﻞ ﻣـﯽ ﮐﻨـﺪ. ﻫـر ﭼﻨﺪ ﮐﻪ ﺑﺎز ﺷﺪن ﺳﺎﺧﺘﺎر آﻧﺰﯾﻢ ﻣﻨﺠﺮ ﺑﻪ ﻣﻬﺎر ﻓﻌﺎﻟﯿﺖ آن ﻧﺸﺪ.

Introduction: Catalase is an enzyme that catalyzes the breakdown of H2O2 into the oxygen and water molecules. On the other hand, aspirin is an important drug, which is used by many patients globally. Because of importance of catalase in antioxidant defense system and the connection between this enzyme and some diseases such as diabetes, in this study, we have investigated the effects of aspirin, which is metabolized in the liver like other drugs, on the structure and function of liver catalase. Materials and Methods: Using different spectroscopic (UV-Visible and Fluorescence) techniques at two temperatures of 25 and 37 0 C we have investigated the changes in the structure and function of catalase. Results: By using kinetics studies obtained from spectroscopic methods as well as the Michaelis–Menten plot, the Km value was measured 40 mM. Kinetic results indicated that aspirin did not change the function of BLC. However, addition of aspirin caused a gradual reduction in the fluorescence emission intensity of catalase. Also‚ the values of binding constants of drug on the enzyme decreased by increasing the temperature. Conclusion: The results of the fluorescence studies showed a decrease in fluorescence emission spectra of catalase, affected by addition of aspirin. Aspirin acts as a quencher with unfolding the three- dimensional structure of catalase, but this unfolding did not inhibit the catalase activity.