NOPR Collection:

Determination of urinary urate with alkylamine glass-bound uricase

2000-04-01T00:00:00Z

Title: Determination of urinary urate with alkylamine glass-bound uricase Authors: Pundir, C S; Bhargava, A K; Gupta, R Abstract: Porcine liver uricase immobilized on alkylamine glass (pore diameter 55 nm) through glutaraldehyde coupling has been found useful in the determination of uric acid in urine. The minimum detection limit was 12.0 μg/0.1 ml sample and the recovery of added uric acid was 91%. The coefficient of variation (CV) were <6.0% and <2.0% for within and between batch assay respectively. A good correlation (r=0.93) was found between urate values obtained by a standard commercial method and the present method. Page(s): 140-142

Calcium-mediated conversion of sucrose to starch in relation to the activities of amylases and sucrose-metabolizing enzymes in sorghum grains raised through liquid culture

2000-04-01T00:00:00Z

Title: Calcium-mediated conversion of sucrose to starch in relation to the activities of amylases and sucrose-metabolizing enzymes in sorghum grains raised through liquid culture Authors: Bhatia, Surekha; Singh, Rangil Abstract: Detached ears of sorghum (Sorghum vulgare) were cultured in complete liquid medium containing Ca²⁺(0, 3,10 and 30 mM) and effect of this ion on the conversion of· sucrose to starch with respect to the activities of amylases, sucrose synthase, sucrose phosphate synthase and soluble invertases were studied in developing grains. Presence of 3 mM Ca²⁺ in culture medium enhanced both accumulation of starch and activity of α-amylase in grain but without having any influence on the activity of β-amylase. However, with 10 and 30 mM Ca²⁺, the accumulation of starch and activities of both amylases decreased and with advancement in culturing period, starch accumulation was further decreased. Irrespective of its concentration, Ca²⁺ enhanced the activities of sucrose synthase (synthesis), sucrose-phosphate synthase, soluble acid invertase and soluble-neutral invertase. Increase in the concentration of Ca²⁺ in culture medium was concomitant with an elevation in relative proportion of sucrose in the grain reflecting a net balance in per cent increase with Ca²⁺ in the activities of sucrose-synthesizing enzymes over sucrose-hydrolysing ones. Based on the results. it is suggested that assimilation of Ca²⁺ by grain is essential for maintaining high activity of α-amylase to generate starch primers required for the conversion or sucrose to starch during grain filling in sorghum. Page(s): 135-139

Succinate oxidase and fumarate reductase systems of filarial parasite Setaria digitata

2000-04-01T00:00:00Z

Title: Succinate oxidase and fumarate reductase systems of filarial parasite Setaria digitata Authors: Unnikrishnan, L S; Raj, R Kaleysa Abstract: Activities of succinate oxidase, fumarate reductase (FR) and succinate dehydrogenase (SOH) under a set of defined conditions were determined in the mitochondrial isolate from Setaria digitata , the filarial parasite from the cattle Bos indicus. Presence of only two activities namely SDH and succinate- UQ reductase of the succinate oxidase system could be detected in S. digitata. In the absence of cytochromes, the 3rd enzyme of the complex namely cytochrome oxidase is absent and it is proposed that an alternative oxidase is responsible for completing the succinate oxidation expressed as succinate oxidase activity. Though SDH and FR catalyse reverse reactions, they responded differently to modulators such as oxaloacetate, aspartate, alanine, pyruvate and fumarate. The degree of response of the two activities against inhibitors of electron transport was also different. Interestingly fumarate caused only 50% inhibition of succinate oxidation, while the effect against FR was more convincing. Page(s): 130-134

Purification and characterization of dihydrofolate reductase from Lactobacillus leichmannii

2000-04-01T00:00:00Z

Title: Purification and characterization of dihydrofolate reductase from Lactobacillus leichmannii Authors: Rao, K Narasimha Abstract: Dihydrofolate reductase (DHFR) (5,6,7,8-THF: NADDP⁺ oxidoreductase, EC 1.5.1.3) was purified 205-fold to apparent homogeneity from the crude extracts of Lactobacillus leichmannii. It has UV absorption maxima at 280 nm, M_r of 20,000, Stokes radius of 0.34 nm and a S_20,w value of 0.12 S. The preparation showed the presence of 168 amino acid residues with threonine and lysine as the NH₂- and COOH- terminal end-groups respectively and a single reactive sulfhydryl group. pCMB inhibited the enzyme activity (IC₅₀ = 2μM). The enzyme has a pH optimum of 7.4 and is thermally inactivated at >35°C. It is activated by 0.1 M KCl and KI and 2M urea. 3-4M urea completely inactivated the enzyme. Enzyme has K_m values of 3.5 μM and 6.2μ M for NADPH and DHF respectively, and a K_ivalue of 7 nM for MTX, the inhibition being competitive. Page(s): 121-129