NISCAIR Online Periodicals Repository Collection: IJEB Vol.44(03) [March 2006]

Cytosolic sulfotransferases

Title: Cytosolic sulfotransferases

Authors: Nimmagadda, Deepthi; Cherala, Ganesh; Ghatta, Srinivas

Abstract: Sulfoconjugation (Sulfation or Sulfonation) is an important reaction in the phase II biotransformation of a wide number of endogenous and foreign chemicals, including: drugs, toxic chemicals, hormones, and neurotransmitters. The reaction is catalyzed by the members of the cytosolic sulfotransferase (SULT) superfamily, consisting of ten functional genes in humans. Sulfation reaction in living cells is reversed by sulfatase, which hydrolyses the sulfonated conjugates. It has a major role in regulating the endocrine status of an individual by modulating the activity of steroid hormones, their biosynthesis, and the metabolism of catecholamines. Sulfonation is a key reaction in the body's ‘chemical’ defense against xenobiotics. Although the primary function of sulfoconjugation is to permit detoxification of the compound, it also results in the activation of chemical procarcinogens, such as certain dietary and environmental agents into carcinogens. In this review, we summarize our current understanding of the structure of mammalian cytosolic sulfotransferases and their role in human steroid associated cancers and in the bioactivation of chemical carcinogens.

Page(s): 171-182

Constitutive acetonitrile hydrolysing activity of Nocardia globerula NHB-2: Optimization of production and reaction conditions

Title: Constitutive acetonitrile hydrolysing activity of Nocardia globerula NHB-2: Optimization of production and reaction conditions

Authors: Kumar, H; Prasad, S; Raj, J; Bhalla, T C

Abstract: Nocardia globerula NHB-2 exhibited an intracellular acetonitrile hydrolysing activity (AHA) when cultivated in nutrient broth supplemented with glucose (10.0 g/l) and yeast extract (1.0 g/l), at pH 8.0, 30°C for 21 hr. Maximum AHA was recorded in the culture containing 0.1 M of sodium phosphate buffer, (pH 8.8) at 45°C for 15 min with 600 μmol of acetonitrile and resting cells of N. globerula NHB-2 equivalent to 1.0 ml culture broth. This activity was stable up to 40°C and was completely inactivated at or above 60°C. About five-fold increase in AHA was observed after optimization of culture and reaction conditions. Under the optimized conditions, this organism hydrolyzed various nitriles and amides such as propionitrile, benzonitrile, acetamide, and acrylamide to corresponding acids. This nitrile/amide hydrolysing activity of N. globerula NHB-2 has potential applications in enzymatic synthesis of organic acids and bioremediation of nitriles and amides contaminated soil and water system.

Page(s): 240-245

Host range nodulation and adaptation in frenchbean rhizobia

Title: Host range nodulation and adaptation in frenchbean rhizobia

Authors: Dhar, B; Mishra, Ashok; Singh, M K

Abstract: The host range nodulation efficiency of four genetically marked frenchbean rhizobial strains (HURR-3, Raj-2, Raj-5 and Raj-6) was studied with five legume hosts namely, frenchbean (Phageolus vulgaris L.), pigeonpea [Cajanus cajan (L.) Millsp.], mungbean [Vigna radiata (L.) Wilezek.], urdbean [Vigna mungo (L.) Hepper.] and soybean [Glycine max (L.) Merril.]. Except soybean and pigeonpea, all other legume hosts were nodulated by two or more frenchbean rhizobial strains tested. Rhizobia were isolated from nodules produced by strains, HURR-3 and Raj-5, on main (frenchbean) and different (mungbean and urdbean) hosts. There was marked improvement in host range nodulation and nitrogen fixation efficiency of rhizobial strains, HURR-3 and Raj-5, after their isolation from chance nodules on different hosts. This is clearly evident from the ability of such isolates to form nodules on pigeonpea besides mungbean and urdbean, and higher nodulation in all the above three different hosts. The phage-susceptibility pattern and intrinsic antibiotic resistance (used as markers) of the two strains did not change after their passage through different hosts. The results indicate that frenchbean rhizobia had undergone some modification in symbiotic behaviour to adapt to wide host range during their passage through different (alternate?) hosts.

Page(s): 250-253

Optimum conditions for L-glutaminase production by actinomycete strain isolated from estuarine fish, Chanos chanos (Forskal, 1775)

Title: Optimum conditions for L-glutaminase production by actinomycete strain isolated from estuarine fish, Chanos chanos (Forskal, 1775)

Authors: Sivakumar, K; Sahu, Maloy Kumar; Manivel, P R; Kannan, L

Abstract: Actinomycetes were isolated from skin, gills and gut contents of estuarine fish, Chanos chanos using Kuster’s agar medium. Out of 20 strains tested, the strain LG-10 which was tentatively identified as Streptomyces rimosus showed L-glutaminase activity. Optimum production of L-glutaminase enzyme (17.51 IU/ml) was observed after 96 h of incubation at 27° C, pH 9 and glucose and malt extract as carbon and nitrogen sources, respectively. The present study indicated scope for the use of S. rimosus as an ideal organism for the industrial production of extracellular L-glutaminase.

Page(s): 256-258