scholarly journals Kinetic Properties of Fungal Polyamine Oxidases and Their Application to Differential Determination of Spermine and Spermidine

1980 ◽  
Vol 44 (12) ◽  
pp. 2955-2960
Author(s):  
Kimiyasu Isobe ◽  
Yoshiki Tani ◽  
Hideaki Yamada
Keyword(s):  
Kinetic Properties ◽  
Polyamine Oxidases

scholarly journals Gating Competence of Constitutively Open CLC-0 Mutants Revealed by the Interaction with a Small Organic Inhibitor

2003 ◽  
Vol 122 (3) ◽  
pp. 295-306 ◽  
Author(s):  
Sonia Traverso ◽  
Laura Elia ◽  
Michael Pusch
Keyword(s):  
Chloride Channels ◽  
Bound State ◽  
Side Chain ◽  
Pore Channel ◽  
Kinetic Properties ◽  
Wild Type ◽  
High Affinity ◽  
Critical Residue ◽  
Fast Gating

Opening of CLC chloride channels is coupled to the translocation of the permeant anion. From the recent structure determination of bacterial CLC proteins in the closed and open configuration, a glutamate residue was hypothesized to form part of the Cl−-sensitive gate. The negatively charged side-chain of the glutamate was suggested to occlude the permeation pathway in the closed state, while opening of a single protopore of the double-pore channel would reflect mainly a movement of this side-chain toward the extracellular pore vestibule, with little rearrangement of the rest of the channel. Here we show that mutating this critical residue (Glu166) in the prototype Torpedo CLC-0 to alanine, serine, or lysine leads to constitutively open channels, whereas a mutation to aspartate strongly slowed down opening. Furthermore, we investigated the interaction of the small organic channel blocker p-chlorophenoxy-acetic acid (CPA) with the mutants E166A and E166S. Both mutants were strongly inhibited by CPA at negative voltages with a >200-fold larger affinity than for wild-type CLC-0 (apparent KD at −140 mV ∼4 μM). A three-state linear model with an open state, a low-affinity and a high-affinity CPA-bound state can quantitatively describe steady-state and kinetic properties of the CPA block. The parameters of the model and additional mutagenesis suggest that the high-affinity CPA-bound state is similar to the closed configuration of the protopore gate of wild-type CLC-0. In the E166A mutant the glutamate side chain that occludes the permeation pathway is absent. Thus, if gating consists only in movement of this side-chain the mutant E166A should not be able to assume a closed conformation. It may thus be that fast gating in CLC-0 is more complex than anticipated from the bacterial structures.

Characterization of microneedles and microchannels for enhanced transdermal drug delivery

2021 ◽  
Author(s):  
Ashana Puri ◽  
Hiep X Nguyen ◽  
Akeemat O Tijani ◽  
Ajay K Banga
Keyword(s):  
Transdermal Delivery ◽  
Transdermal Drug Delivery ◽  
Review Paper ◽  
Low Molecular Weight ◽  
Kinetic Properties ◽  
Different Types ◽  
And Performance ◽  
Tools And Techniques

Microneedle (MN)-based technologies are currently one of the most innovative approaches that are being extensively investigated for transdermal delivery of low molecular weight drugs, biotherapeutic agents and vaccines. Extensive research reports, describing the fabrication and applications of different types of MNs, can be readily found in the literature. Effective characterization tools to evaluate the quality and performance of the MNs as well as for determination of the dimensional and kinetic properties of the microchannels created in the skin, are an essential and critical part of MN-based research. This review paper provides a comprehensive account of all such tools and techniques.

Determination of the thermograms and establishment of the experimenal law for bacterial growth and study of kinetic properties

1993 ◽  
Vol 223 ◽  
pp. 29-33 ◽  
Author(s):  
Zhang Hong-Lin ◽  
Sun Hai-Tao ◽  
Liu Yong-Jun ◽  
Chen Wei-Tian ◽  
Chu Xue-Dao
Keyword(s):  
Bacterial Growth ◽  
Kinetic Properties

scholarly journals Optimized heterologous expression of the human zinc enzyme glyoxalase I

1996 ◽  
Vol 314 (2) ◽  
pp. 463-467 ◽  
Author(s):  
Marianne ÖM ◽  
Bengt MANNERVIK
Keyword(s):  
Culture Medium ◽  
Functional Characterization ◽  
Zinc Salt ◽  
Glyoxalase I ◽  
Kinetic Properties ◽  
Coding Region ◽  
Expression Clone ◽  
High Level ◽  
Inhibition Studies

DNA coding for human glyoxalase I was isolated from a HeLa cell cDNA library by means of PCR. The deduced amino acid sequence differs from previously isolated sequences in that a glutamic acid replaces an alanine in position 111. This variant cDNA may represent the more acidic isoform of glyoxalase I originally identified at the protein level. An expression clone was constructed for high-level production of glyoxalase I in Escherichia coli. For optimal yield of the recombinant protein, silent random mutations were introduced in the cDNA coding region. Antisera against human glyoxalase I were used to select a high-level expression clone. This clone afforded 60 mg of purified enzyme per litre of culture medium. Addition of a zinc salt to the culture medium was essential to obtain an active enzyme and a stoicheiometric metal content. The functional characterization of the recombinant enzyme included determination of kinetic constants for methylglyoxal, phenylglyoxal and p-phenylphenylglyoxal, as well as inhibition studies. The kinetic properties of recombinant glyoxalase I were indistinguishable from those of the enzyme purified from human tissues.

scholarly journals L-asparaginases of extremophilic microorganisms in biomedicine

2020 ◽  
Vol 66 (2) ◽  
pp. 105-123
Author(s):  
M.V. Dumina ◽  
M.A. Eldarov ◽  
D.D. Zdanov ◽  
N.N. Sokolov
Keyword(s):  
Food Industry ◽  
Biomedical Application ◽  
Lymphoblastic Leukemia ◽  
Kinetic Properties ◽  
Lymphoproliferative Diseases ◽  
Ph Tolerance ◽  
Physiological Properties ◽  
Extremophilic Microorganisms ◽  
Extreme Cold

L-asparaginase is extensively used in the treatment of acute lymphoblastic leukemia and several other lymphoproliferative diseases. In addition to its biomedical application, L-asparaginase is also of prospective use in food industry to reduce the formation of acrylamide, which is classified as probably neurotoxic and carcinogenic to human, and in biosensors for determination of L-asparagine level in medicine and food chemistry. The importance of L-asparaginases in different fields, disadvantages of commercial ferments, and the fact that they are widespread in nature stimuli the search for biobetter L-asparaginases from new producing microorganisms. In this regard, extremofile microorganisms exhibit unique physiological properties such as thermal stability, adaptability to extreme cold conditions, salt and pH tolerance and so provide one of the most valuable sources for novel L-asparaginases. The present review summarizes the recent results on studying the structural, functional, physicochemical and kinetic properties, stability of extremophilic L-asparaginases in comparison with their mesophilic homologues.

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