Influence of cationic surfactants and inorganic salts on the enzyme kinetic activity of Mucor javanicus lipase

2020 ◽  
Vol 53 (2) ◽  
pp. 308-316
Author(s):  
Santosh K. Verma ◽  
Kallol K. Ghosh ◽  
Rameshwari Verma ◽  
Shekhar Verma
Keyword(s):  
Cationic Surfactants ◽  
Inorganic Salts ◽  
Enzyme Kinetic ◽  
Kinetic Activity ◽  
Mucor Javanicus

scholarly journals The Vibrio cholerae SpeG Spermidine/Spermine N-Acetyltransferase Allosteric Loop and β6-β7 Structural Elements Are Critical for Kinetic Activity

2021 ◽  
Vol 8 ◽  
Author(s):  
Van Thi Bich Le ◽  
Sofiya Tsimbalyuk ◽  
Ee Qi Lim ◽  
Allan Solis ◽  
Darwin Gawat ◽  
...  
Keyword(s):  
Vibrio Cholerae ◽  
Intracellular Signaling ◽  
Point Mutations ◽  
Structural Evolution ◽  
Transport Systems ◽  
Enzyme Kinetic ◽  
Structural Elements ◽  
Allosteric Site ◽  
Kinetic Activity ◽  
Domains Of Life

Polyamines regulate many important biological processes including gene expression, intracellular signaling, and biofilm formation. Their intracellular concentrations are tightly regulated by polyamine transport systems and biosynthetic and catabolic pathways. Spermidine/spermine N-acetyltransferases (SSATs) are catabolic enzymes that acetylate polyamines and are critical for maintaining intracellular polyamine homeostasis. These enzymes belong to the Gcn5-related N-acetyltransferase (GNAT) superfamily and adopt a highly conserved fold found across all kingdoms of life. SpeG is an SSAT protein found in a variety of bacteria, including the human pathogen Vibrio cholerae. This protein adopts a dodecameric structure and contains an allosteric site, making it unique compared to other SSATs. Currently, we have a limited understanding of the critical structural components of this protein that are required for its allosteric behavior. Therefore, we explored the importance of two key regions of the SpeG protein on its kinetic activity. To achieve this, we created various constructs of the V. cholerae SpeG protein, including point mutations, a deletion, and chimeras with residues from the structurally distinct and non-allosteric human SSAT protein. We measured enzyme kinetic activity toward spermine for ten constructs and crystallized six of them. Ultimately, we identified specific portions of the allosteric loop and the β6-β7 structural elements that were critical for enzyme kinetic activity. These results provide a framework for further study of the structure/function relationship of SpeG enzymes from other organisms and clues toward the structural evolution of members of the GNAT family across domains of life.

Kinetic Aspects of the Interaction of Blood Clotting Enzymes

1965 ◽  
Vol 13 (01) ◽  
pp. 155-175 ◽  
Author(s):  
H. C Hemker ◽  
P.W Hemker ◽  
E. A Loeliger
Keyword(s):  
Kinetic Analysis ◽  
Enzyme Kinetics ◽  
Blood Clotting ◽  
Enzyme System ◽  
Enzyme Kinetic ◽  
Clotting Time ◽  
Standard Methods

SummaryApplication of the methods of enzyme-kinetic analysis to the results of clotting tests is feasible and can yield useful results. However, the standard methods of enzyme kinetics are not applicable without modifications imposed by the peculiarities of the blood-clotting enzyme system. The influence of the following complicating circumstances is calculated :1. Substrate is not present in excess.2. Only relative measures exist for concentrations of substrate or enzymes.3. Enzymes and substrates are often added together.4. Reagents are not pure.5. Clotting-time is our only measure for clotting-velocity.Formulas are deduced, which makes it possible to recognize the effect of these complications.

Experimental and Computational Study of Ecofriendly Synthesize d Imine Cationic Surfactants as Corrosion Inhibitors for Carbon Steel in 1 M HCl

2020 ◽  
Vol 57 (1) ◽  
pp. 45-56 ◽  
Author(s):  
Eman A. Ghiaty ◽  
Dalia E. Mohamed ◽  
Emad A. Badr ◽  
Elshafie A. M. Gad ◽  
Elsayed A. Soliman ◽  
...  
Keyword(s):  
Carbon Steel ◽  
Cationic Surfactants ◽  
Corrosion Inhibitors ◽  
Computational Study

Micellization Behaviour of Cationic Surfactants in the Presence of Food Additives: Conductance and Spectroscopic Investigations

2020 ◽  
Vol 10 ◽  
Author(s):  
Sonika Arti ◽  
Neha Aggarwal
Keyword(s):  
Glutamic Acid ◽  
Cationic Surfactants ◽  
Hydrophobic Interactions ◽  
Food Additives ◽  
Specific Conductance ◽  
Food Additive ◽  
Nmr Studies ◽  
Degree Of Ionization ◽  
Increase With Increase ◽  
Micellization Process

Aim: The micellization behavior of cationic surfactants have been studied in the presence of food additives. Objectives: Micellization behaviour of cationic surfactants, cetyltrimethylammonium bromide (CTAB) and tetradecyltrimethylammonium bromide (TTAB) has been studied in water and in various concentrations of salts (food additives) L-glutamic acid, sodium propionate, sodium citrate tribasic dihydrate and disodium tartrate dihydrate at (298.15, 308.15 and 318.15) K. Methods: Two methods used in the present study are specific conductance measurements and spectroscopy (NMR) studies. Results: From the specific conductance(κ), various parameters such as critical micelle concentration (CMC), degree of ionization of micelle (α), standard Gibbs free energy (ΔGom), enthalpy (ΔHom), and entropy (ΔSom) of micellization have also been calculated. Thermodynamic parameters related to the micellization process were also analyzed through NMR studies. Conclusion: The CMC values are influenced by the presence of food additive. The magnitude of CMC values increase with increase in concentration of food additive. In all the cases, enthalpy of micellization, ∆Hom values are found to be negative whereas entropy of micellization, ∆S om values are positive which indicate that hydrophobic interactions play a major role in the micellization process. Also, NMR studies reveal that tartrate and citrate are more hydrated than glutamic acid and propionate, resulting in more downfield shift.

Depression of freezing temperature of water and water solutions in porous materials

1989 ◽  
Vol 54 (10) ◽  
pp. 2644-2647 ◽  
Author(s):  
Petr Schneider ◽  
Jiří Rathouský
Keyword(s):  
Water Vapor ◽  
Porous Materials ◽  
Inorganic Salt ◽  
Freezing Point ◽  
Freezing Temperature ◽  
Inorganic Salts ◽  
Freezing Point Depression ◽  
Salt Solutions ◽  
Water Solutions

In porous materials filled with water or water solutions of inorganic salts, water freezes at lower temperatures than under normal conditions; the reason is the decrease of water vapor tension above the convex meniscus of liquid in pores. The freezing point depression is not very significant in pores with radii from 0.05 μm to 10 μm (about 0.01-2.5 K). Only in smaller pores, especially when filled with inorganic salt solutions, this depression is important.

Sign in / Sign up

Export Citation Format

Share Document