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Residual Enzyme Activity (residual + enzyme_activity)
Selected AbstractsOptimization of Operating Temperature for Continuous Immobilized Glucose Isomerase Reactor with Pseudo Linear KineticsENGINEERING IN LIFE SCIENCES (ELECTRONIC), Issue 5 2004N.M. Faqir Abstract In this work, the optimal operating temperature for the enzymatic isomerization of glucose to fructose using a continuous immobilized glucose isomerase packed bed reactor is studied. This optimization problem describing the performance of such reactor is based on reversible pseudo linear kinetics and is expressed in terms of a recycle ratio. The thermal deactivation of the enzyme as well as the substrate protection during the reactor operation is considered. The formulation of the problem is expressed in terms of maximization of the productivity of fructose. This constrained nonlinear optimization problem is solved using the disjoint policy of the calculus of variations. Accordingly, this method of solution transforms the nonlinear optimization problem into a system of two coupled nonlinear ordinary differential equations (ODEs) of the initial value type, one equation for the operating temperature profile and the other one for the enzyme activity. The ODE for the operating temperature profile is dependent on the recycle ratio, operating time period, and the reactor residence time as well as the kinetics of the reaction and enzyme deactivation. The optimal initial operating temperature is selected by solving the ODEs system by maximizing the fructose productivity. This results into an unconstrained one-dimensional optimization problem with simple bounds on the operating temperature. Depending on the limits of the recycle ratio, which represents either a plug flow or a mixed flow reactor, it is found that the optimal temperature of operation is characterized by an increasing temperature profile. For higher residence time and low operating periods the residual enzyme activity in the mixed flow reactor is higher than that for the plug flow reactor, which in turn allows the mixed flow reactor to operate at lower temperature than that of the plug flow reactor. At long operating times and short residence time, the operating temperature profiles are almost the same for both reactors. This could be attributed to the effect of substrate protection on the enzyme stability, which is almost the same for both reactors. Improvement in the fructose productivity for both types of reactors is achieved when compared to the constant optimum temperature of operation. The improvement in the fructose productivity for the plug flow reactor is significant in comparison with the mixed flow reactor. [source] HIGH PRESSURE INACTIVATION OF PECTIN METHYL ESTERASE IN ORANGE JUICE USING COMBINATION TREATMENTSJOURNAL OF FOOD BIOCHEMISTRY, Issue 6 2001S. BASAK ABSTRACT The contribution of several high pressure (HP) processing related factors (pressure level, 300-400 MPa; pressure cycle, 1-3, and pressure-hold time, 30,120 min) on the inactivation of pectin methyl esterase (PME) in single strength (pH 3.7 and 11.4 °Brix) and concentrated (pH 3.5 and 42 °Brix) orange juice was evaluated. A response surface methodology was employed to model the combined effects of factors on the enzyme inactivation. The main effects were described by linear or quadratic functions. For both single strength and concentrated orange juices, the effects of all three main factors and some interactions (pressure level, cycle and holding time) were statistically significant (p<0.05). The dual nature of pressure inactivation of PME (with an instantaneous inactivation due to a pressure pulse, instantaneous pressure fall, and first order rate of inactivation during the pressure hold, yielding D and z values) reported in earlier studies was confirmed. Combination models were developed to predict the residual enzyme activity as influenced by the pressure level, number of pressure cycles and pressure hold time. [source] Smith-Lemli-Opitz syndrome: New mutation with a mild phenotypeAMERICAN JOURNAL OF MEDICAL GENETICS, Issue 1 2002Chitra Prasad Abstract Smith-Lemli-Opitz syndrome (SLOS) (Online Mendelian Inheritance in Man, OMIMÔ, 2001, http://www.ncbi.nlm.nih.gov/omim/ for SLOS, MIM 270400) is an autosomal recessive disorder of cholesterol biosynthesis caused by mutations of the 3,-hydroxysterol ,7 -reductase gene, DHCR7. We report on a female infant with an exceptionally mild phenotype of SLOS, in whom molecular studies identified a new mutation in DHCR7. The proposita initially presented with feeding difficulties, failure to thrive, hypotonia, mild developmental delay, and oral tactile aversion. She had minor facial anomalies and 2,3 syndactyly of her toes in both feet. The plasma cholesterol was borderline low at 2.88 mmol/L (normal 2.97,4.40 mmol/L). Elevated plasma 7-dehydrocholesterol level of 200.0 ,mol/L confirmed the clinical diagnosis of SLOS. Molecular analysis demonstrated compound heterozygosity for IVS8-1G ,C and Y280C, a new missense mutation in DHCR7. Since the other mutation in this patient is a known null mutation, this newly discovered mutation is presumably associated with significant residual enzyme activity and milder expression of clinical phenotype. © 2002 Wiley-Liss, Inc. [source] Western blotting analysis of the ,-hexosaminidase ,- and ,-subunits in cultured fibroblasts from cases of various forms of GM2 gangliosidosisACTA NEUROLOGICA SCANDINAVICA, Issue 6 2002K. Utsumi Objectives, The GM2 gangliosidoses are a group of genetic disorders caused by the accumulation of ganglioside GM2 in neuronal cells. We examined the , - and , -subunits of , -hexosaminidases by a non-radioisotopes detecting system to evaluate whether it was a useful method for understanding of the pathophysiologies of GM2 gangliosidoses. Materials and methods, We investigated the , - and , -subunits of , -hexosaminidases in cultured fibroblasts from cases of various forms of GM2 gangliosidosis by means of Western blotting and a chemiluminescence detection system. Results, In a patient with infantile Tay-Sachs disease [HEXA genotype, Int5-SA(g,1,t)/Int5-SA(g,1,t)], the mature , -subunit was undetectable. In a patient with infantile Sandhoff disease (HEXB genotype, C534Y/C534Y), the mature , -subunit was deficient. However, a small amount of the mature , -subunit was detected in a patient with adult Sandhoff disease (HEXB genotype, R505Q(+I207V)/R505Q(+I207V)), which may have resulted in the residual enzyme activity and mild clinical course. Normal amounts of , - and , -subunits were detected in a patient with GM2 activator deficiency. Conclusion, This method is easy and sensitive for detecting target proteins, and is useful for clarification of the pathophysiologies of GM2 gangliosidoses. [source] Correlation between severity of mucopolysaccharidoses and combination of the residual enzyme activity and efficiency of glycosaminoglycan synthesisACTA PAEDIATRICA, Issue 4 2009Ewa Piotrowska Abstract Aim: To develop a method for prediction of severity and clinical course of mucopolysaccharidoses (MPS), a group of inherited metabolic diseases. Methods: Various biochemical and clinical parameters (including estimation of the level of clinical severity, presence of specific mutations, residual enzyme activity, urinary glycosaminoglycan (GAG) excretion, storage of GAG in fibroblasts and efficiency of GAG synthesis) of patients suffering from MPS types II, IIIA and IIIB were determined. Correlations between genetic, biochemical and clinical parameters were tested. Results: We found that efficiency of GAG synthesis may contribute to the level of severity of MPS. It appears that (i) combination of low or average efficiency of GAG synthesis and the presence of residual activity of the enzyme is responsible for an attenuated phenotype, (ii) a lack of detectable residual enzyme activity causes a severe phenotype, irrespective of the efficiency of GAG synthesis and (iii) high efficiency of GAG synthesis leads to a severe phenotype, even if residual enzyme activity is detected. This correlation was found to be valid in 15 out of 17 patients tested. Conclusion: Analysis of efficiency of GAG synthesis and residual activity of the enzyme may be considered for prediction of severity of MPS patients' clinical phenotypes. [source] | |||||||||||||