scholarly journals Macromolecular Crowding Enhances Catalytic Efficiency and Stability of α-Amylase

2013 ◽  
Vol 2013 ◽  
pp. 1-7 ◽  
Author(s):  
Jay Kant Yadav
Keyword(s):  
Thermal Stability ◽  
Relative Effectiveness ◽  
Macromolecular Crowding ◽  
Catalytic Efficiency ◽  
Crowding Effect ◽  
Functional Attributes ◽  
Marginal Change ◽  
High Concentrations ◽  
Thermal Stability Of

In the present study an attempt was made to investigate the macromolecular crowding effect on functional attributes of α-amylase. High concentrations of sugar based cosolvents, (e.g., trehalose, sucrose, sorbitol, and glycerol) were used to mimic the macromolecular crowding environment (of cellular milieu) under in vitro conditions. To assess the effect of macromolecular crowding, the activity and structural properties of the enzyme were evaluated in the presence of different concentrations of the above cosolvents. Based on the results it is suggested that the macromolecular crowding significantly improves the catalytic efficiency of the enzyme with marginal change in the structure. Out of four cosolvents examined, trehalose was found to be the most effective in consistently enhancing thermal stability of the enzyme. Moreover, the relative effectiveness of the above cosolvents was found to be dependent on their concentration used.

In silico and in vitro Approaches to Elucidate the Thermal Stability of Human UDP-glucuronosyltransferase (UGT) 1A9

2009 ◽  
Vol 24 (3) ◽  
pp. 235-244 ◽  
Author(s):  
Ryoichi Fujiwara ◽  
Miki Nakajima ◽  
Tetsunori Yamamoto ◽  
Hidemi Nagao ◽  
Tsuyoshi Yokoi
Keyword(s):  
Thermal Stability ◽  
In Silico ◽  
Udp Glucuronosyltransferase ◽  
Thermal Stability Of

scholarly journals Influence of High-Concentration LLDPE on the Manufacturing Process and Morphology of Pitch/LLDPE Fibres

Crystals ◽  
2021 ◽  
Vol 11 (9) ◽  
pp. 1099
Author(s):  
Salem Mohammed Aldosari ◽  
Muhammad A. Khan ◽  
Sameer Rahatekar
Keyword(s):  
Mechanical Properties ◽  
Thermal Stability ◽  
Tensile Modulus ◽  
Low Density Polyethylene ◽  
Low Density ◽  
Linear Low Density Polyethylene ◽  
High Concentration ◽  
Scanning Electron Microscope Study ◽  
High Concentrations ◽  
Thermal Stability Of

A high modulus of elasticity is a distinctive feature of carbon fibres produced from mesophase pitch. In this work, we expand our previous study of pitch/linear low-density polyethylene blend fibres, increasing the concentration of the linear low-density polyethylene in the blend into the range of from 30 to 90 wt%. A scanning electron microscope study showed two distinct phases in the fibres: one linear low-density polyethylene, and the other pitch fibre. Unique morphologies of the blend were observed. They ranged from continuous microfibres of pitch embedded in linear low-density polyethylene (occurring at high concentrations of pitch) to a discontinuous region showing the presence of spherical pitch nodules (at high concentrations of linear low-density polyethylene). The corresponding mechanical properties—such as tensile strength, tensile modulus, and strain at failure—of different concentrations of linear low-density polyethylene in the pitch fibre were measured and are reported here. Thermogravimetric analysis was used to investigate how the increased linear low-density polyethylene content affected the thermal stability of linear low-density polyethylene/pitch fibres. It is shown that selecting appropriate linear low-density polyethylene concentrations is required, depending on the requirement of thermal stability and mechanical properties of the fibres. Our study offers new and useful guidance to the scientific community to help select the appropriate combinations of linear low-density polyethylene/pitch blend concentrations based on the required mechanical property and thermal stability of the fibres.

Effects of glycine betaine and glycerophosphocholine on thermal stability of ribonuclease

1998 ◽  
Vol 274 (4) ◽  
pp. F762-F765 ◽  
Author(s):  
Maurice B. Burg ◽  
Eugenia M. Peters
Keyword(s):  
Thermal Stability ◽  
Tissue Culture ◽  
Glycine Betaine ◽  
Metabolic Cost ◽  
Rnase A ◽  
Renal Cells ◽  
And Function ◽  
Thermal Stability Of

Urea in renal medullas is sufficiently high to perturb macromolecules, yet the cells survive and function. The counteracting osmolytes hypothesis holds that methylamines, such as glycine betaine (betaine) and glycerophosphocholine (GPC) in renal medullas, stabilize macromolecules and oppose the effects of urea. Although betaine counteracts effects of urea on macromolecules in vitro and protects renal cells from urea in tissue culture, renal cells accumulate GPC rather than betaine in response to high urea both in vivo and in tissue culture. A proposed explanation is that GPC counteracts urea more effectively than betaine. However, we previously found GPC slightly less effective than betaine in counteracting inhibition of pyruvate kinase activity by urea. To test another macromolecule, we now compare GPC and betaine in counteracting reduction of the thermal stability of RNase A by urea. We find that urea decreases the thermal transition temperature and that betaine and GPC increase it, counteracting urea approximately equally. Therefore, the preference for GPC in response to high urea presumably has some other basis, such as a lower metabolic cost of GPC accumulation.

Synthesis and investigation of in vitro cytotoxic activities and thermal stability of novel pyridine derivative platinum (II) complexes vis a vis DFT studies

Polyhedron ◽  
2021 ◽  
pp. 115492
Author(s):  
Emine Kutlu ◽  
Fatih Mehmet Emen ◽  
Görkem Kismali ◽  
Neslihan Kaya Kınaytürk ◽  
Ali Ihsan Karacolak ◽  
...  
Keyword(s):  
Thermal Stability ◽  
Pyridine Derivative ◽  
Cytotoxic Activities ◽  
Dft Studies ◽  
Thermal Stability Of

scholarly journals Competition and allostery govern substrate selectivity of cyclooxygenase-2

2015 ◽  
Vol 112 (40) ◽  
pp. 12366-12371 ◽  
Author(s):  
Michelle M. Mitchener ◽  
Daniel J. Hermanson ◽  
Erin M. Shockley ◽  
H. Alex Brown ◽  
Craig W. Lindsley ◽  
...  
Keyword(s):  
Mechanistic Model ◽  
Inverse Correlation ◽  
Catalytic Efficiency ◽  
Cyclooxygenase 2 ◽  
Allosteric Site ◽  
Raw264.7 Macrophages ◽  
Allosteric Sites ◽  
Cox 2 ◽  
High Concentrations

Cyclooxygenase-2 (COX-2) oxygenates arachidonic acid (AA) and its ester analog, 2-arachidonoylglycerol (2-AG), to prostaglandins (PGs) and prostaglandin glyceryl esters (PG-Gs), respectively. Although the efficiency of oxygenation of these substrates by COX-2 in vitro is similar, cellular biosynthesis of PGs far exceeds that of PG-Gs. Evidence that the COX enzymes are functional heterodimers suggests that competitive interaction of AA and 2-AG at the allosteric site of COX-2 might result in differential regulation of the oxygenation of the two substrates when both are present. Modulation of AA levels in RAW264.7 macrophages uncovered an inverse correlation between cellular AA levels and PG-G biosynthesis. In vitro kinetic analysis using purified protein demonstrated that the inhibition of 2-AG oxygenation by high concentrations of AA far exceeded the inhibition of AA oxygenation by high concentrations of 2-AG. An unbiased systems-based mechanistic model of the kinetic data revealed that binding of AA or 2-AG at the allosteric site of COX-2 results in a decreased catalytic efficiency of the enzyme toward 2-AG, whereas 2-AG binding at the allosteric site increases COX-2’s efficiency toward AA. The results suggest that substrates interact with COX-2 via multiple potential complexes involving binding to both the catalytic and allosteric sites. Competition between AA and 2-AG for these sites, combined with differential allosteric modulation, gives rise to a complex interplay between the substrates, leading to preferential oxygenation of AA.

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