76th AM SBCI ABSTRACTS NOVEMBER, 2007

BC 13

Effect of temperature and pH on stability of porcine pancreatic lipase in presence of polyols and sugars

Gangadhara, and V. Prakash

Department of Protein Chemistry and Technology

Central Food Technological Research Institute

Mysore – 570 020, India

E-Mail: gangu_bn@yahoo.co.in

Porcine pancreatic lipase (triacylglycerol acylhydrolases - E.C. 3.1.1.3) is a key enzyme for the intraluminar digestion of fats and is one of the most widely used enzymes for biotechnological aspects. Pancreatic lipase is a single polypeptide chain of 50 kDa. The effect of polyols and sugars on lipase from porcine pancreas activity, kinetic measurements and stability were studied by comparing the enzymatic activity and conformation of the enzyme at optimum, lower pH and high temperature conditions. The polyols and sugars used (glycerol, xylitol, sorbitol, trehalose and sucrose). At optimum condition these additives didn’t show any change in the activity. But at lower pH and higher temperature these additives were protecting the enzyme in terms of both activity and conformational stability. The fluorescence spectra shows blue shift with increase in relative fluorescence intensity and far UV-CD studies shows these additives protecting the structure of the enzyme with increase in α-helical content. At lower pH (pH 4.0) native enzyme loses 90% of the enzyme activity but it retains 24, 44, 61, 35 & 48% of the activity in 40% glycerol, xylitol, sorbitol, sucrose & trehalose with increase in k_cat values minimizing K_m values. The data support that these additives were very effective in providing protection against loss of activity at higher temperature and at low pH by shifting the denaturation equilibrium towards the native state.

BC 14

Title: Effect of fish oil administration on isolated rat colonocytes

Agnihotri N.*, Sarotra P.*, Singh P.K.*, Aggarwal R.**, Vidhya K.*

*Department of Biochemistry, Panjab University, Chandigarh.

** Department of Pathology, PGIMER, Chandigarh, India.

email:navneetneeraj@hotmail.com

Background –Dietary n-3 polyunsaturated fatty acids acts on diverse physiological processes influencing normal health and chronic disease and are found to be very sensitive to peroxidation. Because the colonic mucosa may be subjected to significant changes after fish oil administration, knowledge of the oxidant defense mechanisms in the colon is of biologic and potential clinical importance.

Aim – The purpose of the present study was to determine the effects of dietary fish oil on the balance between generation of reactive species and the antioxidants in isolated colonocytes.

Method –The animals were divided into two groups. Control group was fed standard pellet diet while the test group was given 1 ml fish oil orally for 21 days in addition to standard pellet diet. Indexes of oxidative stress (lipid peroxidation, nitrite levels) and protective antioxidants (superoxide dismutase, catalase, glutathione-S-transferase and reduced glutathione) were estimated in the isolated colonocytes.

Result – As compared to the control group, the test group showed-

• A significant increase in lipid peroxidation, nitrite levels and in the superoxide dismutase and glutathione-S-transferase activity,
• A significant decrease in catalase activity and
• No significant change in reduced glutathione levels

Conclusion – The results of the present study suggested that the consumption of fish oil altered the balance between prooxidant and antioxidant levels leading to oxidative stress in colonic mucosa.