Paraoxonase 1 Polymorphism p.Q192R in Patients With Dementia

PON1 PCR-RFLP polymorphism frequency and enzyme activity were determined in 223 patients with dementia (94 with AD, 55 with VaD and 74 with MD) and in 100 age and sex matched controls without dementia. I found no statistical significance of genotype frequencies between analyzed groups. 
Paraoxonase 1 activity was lower in patients carrying the R allele in locus 192 as compared with the R allele non-carriers. The results showed statistically significant association between PON1 polymorphism and enzyme activity and thus can suggest an important relationship between different isoforms of PON1, enzyme activity and dementia

Astroenzymology – the environmental limits of enzyme activity

Using organisms from extreme terrestrial environments as models for extraterrestrial life may lead us to underestimate the range of environments that life may inhabit. An alternative approach is to inspect the range of conditions over which crucial biomolecules might function. Recent investigations of enzyme activity suggest that they have the potential to function over a wider range of environmental conditions than expected. Although the upper temperature limit for enzyme stability is unclear, some enzymes are active up to 130°C. The evidence is that the instability of enzymes is a functional requirement, rather then because of any restraint on achieving higher stability. There is no evidence that enzyme activity ceases at low temperatures; it declines in a predictable manner to the lowest temperature at which it has been possible to make measurements, -100°C. It has been generally accepted that dehydration stops enzyme activity but this acceptance may have arisen partly from the technical difficulty of assessing enzyme activity without a fluid medium for diffusion. Experiments using anhydrous organic solvents or gas phase substrates suggest activity occurs in enzymes at very low hydration

Cellulase Production by Wild-type Aspergillus niger, Penicillium chrysogenum and Trichoderma harzianum Using Waste Cellulosic Materials

Waste cellulosic materials (corncob, sawdust and sugarcane pulp) and crystalline cellulose induced cellulase production in wild strains of Aspergillus niger, Penicillium chrysogenum and Trichoderma harzianum isolated from a wood-waste dump in Lagos, Nigeria. Cellulose-supplemented media gave the maximum cellulase activity of 0.54, 0.67 and 0.39 units mg Protein-1 for A. niger, P. chrysogenum and T. harzianum respectively. The maximum enzyme activity for A. niger was obtained at 36 h of cultivation, while P. chrysogenum and T. harzianum gave their maximum enzyme activities at 12 and 60 h respectively. For the cellulosic wastes, highest enzyme activity was obtained with sawdust where A. niger, P. chrysogenum and T. harzianum gave the maximum enzyme activity of 0.30, 0.24 and 0.20 units mg Protein-1 respectively after 144 h of cultivation. A. niger recorded the highest enzyme activity with any of the three cellulosic materials followed by P. chrysogenum. It thus appears that the use of sawdust presents the best option for low-cost commercial production of cellulase using A. niger and P. chrysogenum as discussed herewith

Enzyme activity and dynamics in near-anhydrous conditions

Water is widely assumed to be essential for life 1, although the exact molecular basis of this requirement is unclear 2-4. Water facilitates protein motions 5-9 and although enzyme activity has been demonstrated at low hydrations in organic solvents 10-13, such non-aqueous solvents may allow the necessary motions for catalysis. To examine enzyme function in the absence of solvation and bypass diffusional constraints we have tested the ability of an esterase to catalyse alcoholysis as an anhydrous powder, using a closed reaction system in which the substrates and products of the enzyme reaction are gaseous 14-15, and where the water content can be well defined 16. At hydrations equivalent to 3 (±2) molecules of water per molecule of enzyme, activity is observed that is several orders of magnitude greater than non-enzymatic catalysis. Neutron spectroscopy indicates that the fast (≤nanosecond) global anharmonic dynamics of the anhydrous functional enzyme are heavily suppressed. The results indicate that neither hydration water nor the solvent-activated fast anharmonic dynamics are required for enzyme function. An implication of these results is that one of the essential requirements of water for life may lie with its role as a diffusion medium rather than any of its more specific properties

Actinidin : the predominant protease in kiwifruit : a thesis presented in partial fulfilment of the requirements for the degree of Master of Philosophy in Food technology at Massey University, Manawatū, New Zealand

Kiwifruit protein (actinidin) has been widely known as a protease. Kiwifruit protein has the potential of utilization in food industry as an enzyme that aids food digestion. In this project, the soluble kiwifruit proteins were extracted from fresh Hayward and SunGold kiwifruit. Soluble kiwifruit proteins were analysed by the Hartree-Lowry method, SDS-PAGE, enzyme activity determination, ion-exchange chromatography and mass spectrometry. Anti-actinidin antibodies were raised by the injection of purified actinidin into rabbits. The main soluble kiwifruit protein was recognized by anti-actinidin antibodies using Western blot. Moreover, the effects of post-harvest storage on protein content, total enzyme activity and specific enzyme activity were investigated. Comparable studies on both Hayward and SunGold kiwifruit were also carried out in this project. The results showed that Hayward and SunGold kiwifruit had a similar protein content. However, the total enzyme activity of Hayward kiwifruit was about 8 times higher than that of SunGold kiwifruit. The protein with enzyme activity (active actinidin) had a molecular weight of about 27 kDa according to SDS-PAGE and was one of main soluble proteins in Hayward and SunGold kiwifruit. This protease was purified from fresh kiwifruit by anion-exchange chromatography. A polyclonal antibody against actinidin was successfully generated in a rabbit using purified actinidin. Protein with a molecular weight of 27 kDa was recognized by the anti-actinidin antibodies. Post-harvest storage at 1 °C for up to 12 weeks significantly increased the total and specific enzyme activities of SunGold kiwifruit (P<0.05). By contrast, the total and specific enzyme activities of Hayward kiwifruit had a significant decrease after 16 weeks’ storage (P<0.05). Hayward kiwifruit had no significant changes in protein content after storage (P<0.05) while the protein content of SunGold kiwifruit fluctuated in a range from 5.04 to 5.84 mg/mL during post-harvest storage. This study may help to understand the nature of kiwifruit proteins with enzyme activity, which contributes to a full understanding of the health benefits of kiwifruit

Enzyme activity below the dynamical transition at 220 K

Enzyme activity requires the activation of anharmonic motions, such as jumps between potential energy wells. However, in general, the forms and time scales of the functionally important anharmonic dynamics coupled to motion along the reaction coordinate remain to be determined. In particular, the question arises whether the temperature-dependent dynamical transition from harmonic to anharmonic motion in proteins, which has been observed experimentally and using molecular dynamics simulation, involves the activation of motions required for enzyme function. Here we present parallel measurements of the activity and dynamics of a cryosolution of glutamate dehydrogenase as a function of temperature. The dynamical atomic fluctuations faster than ~100 ps were determined using neutron scattering. The results show that the enzyme remains active below the dynamical transition observed at ~220 K, i.e., at temperatures where no anharmonic motion is detected. Furthermore, the activity shows no significant deviation from Arrhenius behavior down to 190 K. The results indicate that the observed transition in the enzyme's dynamics is decoupled from the rate-limiting step along the reaction coordinate

Printed, Flexible Lactate Sensors: Design Considerations Before Performing On-Body Measurements.

This work reports the process of sensor development, optimization, and characterization before the transition to on-body measurements can be made. Sensors using lactate oxidase as a sensing mechanism and tetrathiafulvalene as a mediator were optimized for sporting applications. Optimized sensors show linear range up to 24 mM lactate and sensitivity of 4.8 μA/mM which normalizes to 68 μA*cm-2/mM when accounting for surface area of the sensor. The optimized sensors were characterized 3 different ways: using commercially available reference and counter electrodes, using printed reference and counter electrodes, and using a printed reference electrode with no counter electrode. Sensors intended for measuring sweat must be selective in the presence of sweat constituents. Thus, in addition to traditional characterization in pH 7.0 buffer, we characterized sensor performance in solutions intended to approximate sweat. Sensor performance in pH 7.0 buffer solution was not reflective of sensor performance in artificial sweat, indicating that further characterization is necessary between sensor measurement in pH 7.0 buffer and on-body measurements. Furthermore, we performed enzyme activity measurements and sensor measurements concurrently in five different salts individually, finding that while NH4Cl and MgCl2 do not affect enzyme activity or sensor performance in physiologically relevant ranges of salt concentration, NaCl concentration or KCl concentration decreases enzyme activity and sensor current. On the other hand, CaCl2 induced a nonlinear change in sensor performance and enzyme activity with increasing salt concentration

Properties of Endoglucanase of Penicillium chrysogemum PCL501

Crude extracellular enzyme from a 3-day culture of Penicillium chrysogenum (PCL 501), in basal medium containing cellulose as the sole carbon source, yielded 0.67 ± 0.03, 19.94 ± 1.30 and 8.50 ± 0.50 units mg protein-1 of 1, 4- â-endoglucanase, â-glucosidase and xylanase activity respectively. The crude enzyme was subjected to ammonium sulphate precipitation (80% saturation) and gel filtration. A purification-fold of 7.5 was achieved. Two active fractions of 1, 4 âendoglucanase (EC 3. 2. 1. 4), which exhibited about the same activity towards carboxymethylcellulose (CMC), were obtained and pooled for the subsequent analyses. The endoglucanase gave a Vmax of 10.0 ± 0.4 μmol min-1 mg protein-1 and Km of 11.8 ± 0.4 gL-1 with CMC. The enzyme was most active at pH of 4.5 – 5.0 and temperature range of 40 – 50 OC. The optimum pH was 4.9 while the Optimum temperature was 48 OC. Divalent metal ions and EDTA affected the enzyme activity at 2.0 mM concentrations. Mn2+ and Fe2+ had stimulatory effects on the enzyme whereas Mg2+, Cu2+, Zn2+, Hg2+ and EDTA inhibited the enzyme activity. The effect of Ca2+ was not significant. Over 3- fold increase in the enzyme activity was recorded with Mn2+. Percentage inhibition of 65.9 and 79.7 respectively was obtained with Hg2+ and EDTA. The organism appears to produce two types of endoglucanase which differed in their molecular weight but not significantly in their activity. The enzyme activity was highly stimulated by manganese ion and inhibited by the metal-chelating agent, EDTA