Thermodynamics of hydrolysis of oligosaccharides

Microcalorimetry has been used to determine enthalpy changes for the hydrolysis of a series of oligosaccharides. High-pressure liquid chromatography was used to determine the extents of reaction and to check for any possible side reactions. The enzyme glucan 1,4-alpha-glucosidase was used to bring about the following hydrolysis reactions: (A) maltose(aq) + H2O(liq) = 2D-glucose(aq); (B) maltotriose(aq) + 2H2O(liq) = 3D-glucose(aq); (C) maltotetraose(aq) + 3H2O(liq) = 4D-glucose(aq); (D) maltopentaose(aq) + 4H2O(liq) = 5D-glucose(aq); (E) maltohexaose(aq) + 5H2O(liq) = 6D-glucose(aq); (F) maltoheptaose(aq) + 6H2O(liq) = 7D-glucose(aq); (G) amylose(aq) + nH2O(liq) = (n + 1) D-glucose(aq); and (H) panose(aq) + 2H2O(liq) = 3D-glucose(aq); (J) isomaltotriose(aq) + 2H2O(liq) = 3D-glucose(aq). The enzyme beta-fructofuranosidase was used for the reactions: (K) raffinose(aq) + H2O(liq) = alpha-D-melibiose(aq) + D-fructose(aq); and (L) stachyose(aq) + H2O(liq) = o-alpha-D-galactopyranosyl-(1----6)- alpha-o-D-galactopyranosyl-(1----6)-alpha-D-glucopyranose + D-fructose(aq). The results of the calorimetric measurements (298.15 K, 0.1 M sodium acetate buffer, pH 4.44-6.00) are: delta H0A = -4.55 +/- 0.10, delta H0B = -9.03 +/- 0.10, delta H0C = -13.79 +/- 0.15, delta H0D = -18.12 +/- 0.10, delta H0E = -22.40 +/- 0.15, delta H0F = -26.81 +/- 0.20, delta H0H = 1.46 +/- 0.40, delta H0J = 11.4 +/- 2.0, delta H0K = -15.25 +/- 0.20, and delta H0L = -14.93 +/- 0.20 kJ mol-1. The enthalpies of hydrolysis of two different samples of amylose were 1062 +/- 20 and 2719 +/- 100 kJ mol-1, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)     

Regional localization of the hepatocyte growth factor (HGF) gene to human chromosome 7 band q21.1.

Hepatocyte growth factor (HGF) is a polypeptide involved in liver regeneration. Its amino acid sequence and gene structure are similar to those of coagulation-related serine proteases. We have used a cDNA clone of HGF and flow-sorted human chromosomes to assign this gene to chromosome 7. Fluorescence in situ hybridization of the HGF genomic clones to human metaphase chromosome spreads showed the localization of this gene to 7q21. Estimation of fluorescent signals relative to arbitrary reference points (ARPs) allowed further localization to 7q21.1.     

Effect of medicating ingredients and other additives on microflora present on swine and chicken feeds from a Manitoba mill

The occurrence of microfloral components on medicated and non-medicated swine and chicken feed pellets and crumbles, produced in a Manitoba feed mill between June 1991 and October 1992, was determined. Addition of medicates to feeds generally decreased bacterial incidence and increased that of Eurotium spp. fungi. The effect was less pronounced when copper sulphate was added to medicated swine feeds.Contribution No. 1662.     

Properties of aspartate racemase, a pyridoxal 5'-phosphate-independent amino acid racemase.

Aspartate racemase from Streptococcus thermophilus contains no pyridoxal 5'-phosphate or other cofactors such as FAD, NAD+, and metal ions. It was affected by neither carbonyl reagents such as hydroxylamine nor sodium borohydride but was strongly inhibited by iodoacetamide and other thiol reagents. Aspartate, cysteate, and cysteine sulfinate were the only substrates. The Km values for L- and D-aspartate were 35 and 8.7 mM, respectively. The enzyme catalyzed the exchange of alpha-hydrogen of the substrate with the solvent hydrogen. Racemization of L-aspartate in 2H2O showed an overshooting in the optical rotation of aspartate before the substrate was fully racemized. This shows that the removal of alpha-hydrogen of the substrate is at least partially rate-determining. When L- or D-aspartate was incubated with aspartate racemase in tritiated water, tritium was incorporated preferentially into the product enantiomer. The results strongly suggest that aspartate racemase contains two hydrogen acceptors.     

Features of changes in bioelectric reactions of the cerebral cortex in rats with deafferentation pain syndrome]

In rats with pain syndrome after sciatic nerve section the authors studied spontaneous and evoked bioelectric activity in sensomotor cerebral cortex of both hemispheres. Electrocorticogram showed the presence of hyper-synchronic discharges and paroxysmal peak-wave (700-800 mV) activity in contralateral hemisphere. While stimulating the injured limb the threshold of evoked potentials (EP) was observed to decrease, its amplitude to increase and focus maximum EP activity to extend.     

The effect of interleukin-2 on experimental emotional hypertension]

The effect of human recombinant interleukin-2, one of the potent mediators of the immune system, on the course of emotional hypertension in non-linear white rats has been investigated. A significant and prolonged hypotensive action of a single injection of interleukin-2 in hypertensive rats has been revealed. The data obtained can be a new evidence of participation of immune system in the development of hypertension in experimental animals.