NISCAIR Online Periodicals Repository Collection: IJBB Vol.37(3) [June 2000]

Purification and properties of pigeon kidney arginase

Title: Purification and properties of pigeon kidney arginase

Authors: Khandare, Arjun L; Somvanshi, Baburao S; Lakshmaiah, Nakka

Abstract: Arginase was isolated and purified from the kidneys of pigeon (Coulmba livia) using DEAE-Sepharose CL 6B chromatography, affinity chromatography on arginine-AH-Sepharose 4B and gel filtration on Sephadex G200 in presence of 2-mercaptoethanol. The enzyme migrated to the anode at pH 8.3 on polyacrylamide gel electrophoresis. The purified enzyme showed an average molecular mass of 179,000 daltons, optimal pH of 9.5 and temperature of 55°C and the energy of activation was found to be 10.14 kCal/mol. The K_m for L-argininc was 5.0 mM. The purified enzyme was inhibited by excess product (4 mM ornithine).

Page(s): 198-200

Purification and characterization of a cholinesterase from Haemonchus contortus

Title: Purification and characterization of a cholinesterase from Haemonchus contortus

Authors: Joshi, P; Singh, B P

Abstract: Acetylcholinesterase (AChE) was purified from the extract of adult Haemonchus contortus by gel filtration, ion-exchange and ConA-Sepharose chromatography. The enzyme was also found to be secreted by the parasite during in vitro cultivation which was partially purified from the excretory-secretory products. Presence of enzyme specific antibodies were observed in animals having H. contortus infection. The molecular mass of the enzyme by SDS-PAGE was 144 kDa. The enzyme showed typical Michaelis-Menten kinetics at low substrate concentrations but was inhibited by substrate concentrations greater than 4 mM. The enzyme was stab le at 4°C for several weeks but lost 60% of the activity when heated to 60°C for 5 min. Physostigmine and neostigmine inhibited enzyme activity at low ( μM) concentrations whereas phenyl methyl sulfonyl fluoride (PMSF) and sodium fluoride (NaF) inhibited only at high concentrations (mM) . Significance of secreted AChE in host-parasite relationship is discussed.

Page(s): 192-197

Effect of tri-iodothyronine and di-iodothyronine on lipid metabolism in a teleost Anabas testudineus Bloch

Title: Effect of tri-iodothyronine and di-iodothyronine on lipid metabolism in a teleost Anabas testudineus Bloch

Authors: Varghese, Sheelu; Oommen, Oommen V

Abstract: Intra-muscular injection of two doses of tri-iodothyronine (T₃) and di-iodothyronine (T₂) ( 100 ng and 200 ng) in female Anabas testudineus for a period of five days had a dose dependent effect on plasma T₃ level, increase in the activity of malic enzyme (ME) in liver and decrease in 6-phosphogluconate dehydrogenase (6-PGDH) while there was no change in isocitrate dehydrogenase (ICDH) and glucose 6- phosphate dehydrogenase (G6PDH) activity. H/M ratio decreased only by high doses of T₃ and T₂ indicating increased HMG CoA reductase activity. In cardiac tissue the activity of ICDH decreased while ME activity was unaltered. Lipid analysis showed increased catabolism of cholesterol to free fatty acids. These observation indicate that like T₃, T₂, a product formed by the monodeiodination of thyroid hormones, is also capable of causing lipid metabolism in this teleost.

Page(s): 188-191

Hyperlipidemia and Type-I-5' –monodeiodinase activity: Regulation by selenium supplementation

Title: Hyperlipidemia and Type-I-5' –monodeiodinase activity: Regulation by selenium supplementation

Authors: Kang, B P S; Mehta, Uma; Bansal, M P

Abstract: Effect of feeding high fat diet (HFD) and selenium supplemented high fat diet for three months on Type-I 5' monodeiodenase (5'-DI) activity in rats was studied. There was significant increase in serum cholesterol and triglyceride levels in HFD fed group as compared to the control and when compared to that of Se supplemented group. HFD feeding resulted in decreased serum Se levels but supplementation of Se with HFD resulted in increase in serum Se. Se-dependent glutathione peroxidase (GSH-Px) activity in liver and aorta increased significantly in HFD fed animals and showed additional significant increase on Se supplementation. In HFD fed group, decrease in the low density lipoprotein (LDL) receptor levels was found whereas in the Se-supplemented HFD group the LDL levels were normal. Both serum T₃ and T₄levels decreased significantly on HFD feeding. However, on supplementation of Se to HFD, significant increase in T₃ and T₄ was observed. The activity of 5'-DI in liver decreased significantly in HFD group, but increased in both liver and aorta in Se supplemented HFD group whereas the reverse was true in thyroid.

Page(s): 183-187