In Silico Analysis of Glucose Oxidase H516r and H516d Mutations for an Enzymatic Fuel Cell

Glucose oxidase (GOx) is an oxido-reductase enzyme that catalyzes glucose into hydrogen peroxide and glucono delta-lactone (GDL). GOx has the potential to be used in the medical field. Numerous research concerning the usage of GOx to create enzymatic biofuel cells have been done, nevertheless the results obtained have not been optimal. This research aims to increase the Km values of GOx in order to increase its potential as a material for an enzymatic fuel cell. The amino acid histidine in position 516 is a residue in the active site that plays an important part in the process of glucose oxidation. In this research we mutated H516 by in silico twice resulting in the mutants R516 and D516. The mutations resulted in a change of the docking area for both mutants and in the docking affinity for H516D resulting in higher Km values. This shows that the H516 residue plays an important part in the functions of glucose oxidase and mutation into aspartate could improve glucose oxidase based enzymatic fuel cells.

H2-antagonist in IgE-mediated type I hypersensitivity reactions: what literature says so far?

Histamine is a monoamine synthesized from the amino acid histidine that is well-known for its role in IgE-mediated anaphylaxis but has shown pleiotropic effects on the immune system, especially in order to promote inflammatory responses. H1-receptor antagonist are common drugs used in mild/moderate allergic reactions whereas H2-receptor antagonist are commonly administered in gastric ulcer but showed some properties in allergy too. The EAACI guidelines for diagnosis and treatment of anaphylactic reactions recommend their use as third-line therapy in adjunct to H1-antagonists. The purpose of this article is to produce a complete summary of findings and evidence known so far about the usefulness of H2-receptor antagonist in allergic reactons.

Potential Benefits and Pitfalls of Histidine Supplementation for Cancer Therapy Enhancement

ABSTRACT Dietary supplementation of the amino acid histidine has demonstrable benefits in various clinical conditions. Recent work in a pediatric leukemia mouse model exposed a surprising potential application of histidine supplementation for cancer therapy enhancement. These findings demand a deeper reassessment of the physiological effects and potential drawbacks of histidine supplementation. As pertinent to this question, we discuss the safety of high doses of histidine and its relevant metabolic fates in the human body. We refrain from recommendations or final conclusions because comprehensive preclinical evidence for safety and efficacy of histidine supplementation is still lacking. However, we emphasize the incentive to study the safety of histidine supplementation and its potential to improve the clinical outcome of pediatric blood cancers through a simple dietary supplementation. The need for comprehensive preclinical testing of histidine supplementation in healthy and tumor-bearing mice is fundamental, and we hope that this review will facilitate such studies.

Histidine Utilization Is a Critical Determinant of Acinetobacter Pathogenesis

ABSTRACT Acinetobacter baumannii is a nosocomial pathogen capable of causing a range of diseases, including respiratory and urinary tract infections and bacteremia. Treatment options are limited due to the increasing rates of antibiotic resistance, underscoring the importance of identifying new targets for antimicrobial development. During infection, A. baumannii must acquire nutrients for replication and survival. These nutrients include carbon- and nitrogen-rich molecules that are needed for bacterial growth. One possible nutrient source within the host is amino acids, which can be utilized for protein synthesis or energy generation. Of these, the amino acid histidine is among the most energetically expensive for bacteria to synthesize; therefore, scavenging histidine from the environment is likely advantageous. We previously identified the A. baumannii histidine utilization (Hut) system as being linked to nutrient zinc homeostasis, but whether the Hut system is important for histidine-dependent energy generation or vertebrate colonization is unknown. Here, we demonstrate that the Hut system is conserved among pathogenic Acinetobacter and regulated by the transcriptional repressor HutC. In addition, the Hut system is required for energy generation using histidine as a carbon and nitrogen source. Histidine was also detected extracellularly in the murine lung, demonstrating that it is bioavailable during infection. Finally, the ammonia-releasing enzyme HutH is required for acquiring nitrogen from histidine in vitro, and strains inactivated for hutH are severely attenuated in a murine model of pneumonia. These results suggest that bioavailable histidine in the lung promotes Acinetobacter pathogenesis and that histidine serves as a crucial nitrogen source during infection.

Flexible and Printed Electrochemical Immunosensor Coated with Oxygen Plasma Treated SWCNTs for Histamine Detection

Heterocyclic amine histamine is a well-known foodborne toxicant (mostly linked to “scombroid poisoning”) synthesized from the microbial decarboxylation of amino acid histidine. In this work, we report the fabrication of a flexible screen-printed immunosensor based on a silver electrode coated with single-walled carbon nanotubes (SWCNTs) for the detection of histamine directly in fish samples. Biosensors were realized by first spray depositing SWCNTs on the working electrodes and by subsequently treating them with oxygen plasma to reduce the unwanted effects related to their hydrophobicity. Next, anti-histamine antibodies were directly immobilized on the treated SWCNTs. Histamine was detected using the typical reaction of histamine and histamine-labeled with horseradish peroxidase (HRP) competing to bind with anti-histamine antibodies. The developed immunosensor shows a wide linear detection range from 0.005 to 50 ng/mL for histamine samples, with a coefficient of determination as high as 98.05%. Average recoveries in fish samples were observed from 96.00% to 104.7%. The biosensor also shows good selectivity (less than 3% relative response for cadaverine, putrescine, and tyramine), reproducibility, mechanical and time stability, being a promising analytical tool for the analysis of histamine, as well as of other food hazards.

Synthesis and antimicrobial evaluation of Histidine Cinnamaldehyde Schiff base containing structural feature of 1, 3, 4-thiadiazole heterocyclic moiety

Reaction of aqueous solution of amino acid Histidine with ethanolic solution Cinnamaldehyde to synthesize the desired Schiff base. Then, the derivative of 1, 3, 4-thiadiazole ring have been synthesized by reaction of the imine derivative with Thiosemicarbazide in presence of POCL3. The entire intermediate and final compound characterized and identified by elemental microanalysis as melting point, FT-IR spectra, 1H-NMR spectroscopy. Agar Well Diffusion method evaluated the antimicrobial activity on gram positive bacteria such as Staphylococcus aureus and Streptococcus pneumonia and gram-negative bacteria such as E coli & Acinetobacter species and also antifungal activity had been studied on one type of fungi (candida albicans).

High proton conductivity behavior in a 2D metal sulfite constructed from a histidine ligand

In the presence of the amino acid histidine, an inorganic–organic hybrid metal sulfite (compound 1), has been prepared under hydrothermal conditions. Compound 1 shows a high proton conductivity of, approximately 10−3 S cm−1 at 348 K and 98% RH.

Membrane adsorber for endotoxin removal

ABSTRACT The surface of flat-sheet nylon membranes was modified using bisoxirane as the spacer and polyvinyl alcohol as the coating polymer. The amino acid histidine was explored as a ligand for endotoxins, aiming at its application for endotoxin removal from aqueous solutions. Characterization of the membrane adsorber, analysis of the depyrogenation procedures and the evaluation of endotoxin removal efficiency in static mode are discussed. Ligand density of the membranes was around 7 mg/g dry membrane, allowing removal of up to 65% of the endotoxins. The performance of the membrane adsorber prepared using nylon coated with polyvinyl alcohol and containing histidine as the ligand proved superior to other membrane adsorbers reported in the literature. The lack of endotoxin adsorption on nylon membranes without histidine confirmed that endotoxin removal was due to the presence of the ligand at the membrane surface. Modified membranes were highly stable, exhibiting a lifespan of approximately thirty months.

TRH-Like Peptides

TRH-like peptides are characterized by substitution of basic amino acid histidine (related to authentic TRH) with neutral or acidic amino acid, like glutamic acid, phenylalanine, glutamine, tyrosine, leucin, valin, aspartic acid and asparagine. The presence of extrahypothalamic TRH-like peptides was reported in peripheral tissues including gastrointestinal tract, placenta, neural tissues, male reproductive system and certain endocrine tissues. Work deals with the biological function of TRH-like peptides in different parts of organisms where various mechanisms may serve for realisation of biological function of TRH-like peptides as negative feedback to the pituitary exerted by the TRH-like peptides, the role of pEEPam such as fertilization-promoting peptide, the mechanism influencing the proliferative ability of prostatic tissues, the neuroprotective and antidepressant function of TRH-like peptides in brain and the regulation of thyroid status by TRH-like peptides.