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1.
Plant Physiol ; 191(2): 1305-1323, 2023 02 12.
Artigo em Inglês | MEDLINE | ID: mdl-36417197

RESUMO

Nitrogen is critical for plant growth and development. With the increase of nitrogen fertilizer application, nitrogen use efficiency decreases, resulting in wasted resources. In apple (Malus domestica) rootstocks, the potential molecular mechanism for improving nitrogen uptake efficiency to alleviate low-nitrogen stress remains unclear. We utilized multi-omics approaches to investigate the mechanism of nitrogen uptake in two apple rootstocks with different responses to nitrogen stress, Malus hupehensis and Malus sieversii. Under low-nitrogen stress, Malus sieversii showed higher efficiency in nitrogen uptake. Multi-omics analysis revealed substantial differences in the expression of genes involved in flavonoid and lignin synthesis pathways between the two materials, which were related to the corresponding metabolites. We discovered that basic helix-loop-helix 130 (bHLH130) transcription factor was highly negatively associated with the flavonoid biosynthetic pathway. bHLH130 may directly bind to the chalcone synthase gene (CHS) promoter and inhibit its expression. Overexpressing CHS increased flavonoid accumulation and nitrogen uptake. Inhibiting bHLH130 increased flavonoid biosynthesis while decreasing lignin accumulation, thus improving nitrogen uptake efficiency. These findings revealed the molecular mechanism by which bHLH130 regulates flavonoid and lignin biosyntheses in apple rootstocks under low-nitrogen stress.


Assuntos
Malus , Malus/metabolismo , Nitrogênio/metabolismo , Lignina/metabolismo , Multiômica , Flavonoides/metabolismo , Regulação da Expressão Gênica de Plantas
2.
Zhonghua Yi Xue Yi Chuan Xue Za Zhi ; 40(4): 402-407, 2023 Apr 10.
Artigo em Zh | MEDLINE | ID: mdl-36972932

RESUMO

OBJECTIVE: To analyze the clinical phenotype and genetic variant of a child with Snijders Blok-Campeau syndrome (SBCS). METHODS: A child who was diagnosed with SBCS in June 2017 at Henan Children's Hospital was selected as the study subject. Clinical data of the child was collected. Peripheral blood samples of the child and his parents were collected and the extraction of genomic DNA, which was subjected to trio-whole exome sequencing (trio-WES) and genome copy number variation (CNV) analysis. Candidate variant was verified by Sanger sequencing of his pedigree members. RESULTS: The main clinical manifestations of the child have included language delay, intellectual impairment and motor development delay, which were accompanied with facial dysmorphisms (broad forehead, inverted triangular face, sparse eyebrows, widely spaced eyes, narrow palpebral fissures, broad nose bridge, midface hypoplasia, thin upper lip, pointed jaw, low-set ears and posteriorly rotated ears). Trio-WES and Sanger sequencing revealed that the child has harbored a heterozygous splicing variant of the CHD3 gene, namely c.4073-2A>G, for which both of his parents were of wild-type. No pathogenic variant was identified by CNV testing. CONCLUSION: The c.4073-2A>G splicing variant of the CHD3 gene probably underlay the SBCS in this patient.


Assuntos
Variações do Número de Cópias de DNA , Splicing de RNA , Heterozigoto , Linhagem , Fenótipo , Mutação
3.
Zhonghua Yi Xue Yi Chuan Xue Za Zhi ; 38(3): 219-223, 2021 Mar 10.
Artigo em Zh | MEDLINE | ID: mdl-33751528

RESUMO

OBJECTIVE: To investigate the clinical phenotype and genetic characteristics of a patient with hypohidrotic ectodermal dysplasia (HED) due to partial deletion of EDA gene. METHODS: The child has presented with HED complicated with epilepsy. Family trio whole exome sequencing (Trio-WES), copy number variation sequencing (CNV-seq), and karyotype analysis were carried out to explore the underlying genetic etiology. RESULTS: The proband, a 7-year-and-8-month-old boy, presented with thin curly hair, thin and sparse eyebrow, xerosis cutis, susceptibility to hyperthermia from childhood, hypohidrosis, sharp/sparse/absent teeth, saddle nose, prominent forehead, auricle adulation and seizure. He was found to have a normal chromosomal karyotype, and no abnormality was found by Trio-WES. Genome-wide CNV-seq revealed a 341.90 kb deletion at Xq13.1q13.1 (chrX: 68 796 566-69 138 468). As verified by PCR-electrophoresis, the deletion has removed part of the EDA gene. The deletion was derived from his mother with normal hair, mild xerosis cutis, and sparse, decidulated and nail-like teeth. The mother was detected with a heterozygous 242.10 kb deletion at Xq13.1q13.1 (chrX: 68 836 154-69 078 250). CONCLUSION: Both the proband and his mother have carried a Xq13.1 microdeletion involving part of the EDA gene. The clinical phenotypes of the mother and the proband were consistent with the clinical characteristics of X-linked recessive HED, for which partial deletion of the EDA gene is probably accountable.


Assuntos
Variações do Número de Cópias de DNA , Displasia Ectodérmica Anidrótica Tipo 1 , Displasia Ectodérmica , Criança , Displasia Ectodérmica Anidrótica Tipo 1/genética , Ectodisplasinas/genética , Humanos , Masculino , Fenótipo
4.
BMC Oral Health ; 21(1): 479, 2021 09 27.
Artigo em Inglês | MEDLINE | ID: mdl-34579707

RESUMO

BACKGROUND: Periodontitis can lead to the destruction of periodontium and adversely influence the overall health, wellbeing, and quality of life. However, studies on the relationship between severe periodontitis and serum 25-hydroxyvitamin D [25(OH)D] are limited. This study is designed to explore the relationship between 25(OH)D and severe periodontitis. METHODS: A cross-section study of 2928 participants enrolled from the National Health and Nutrition Examination Survey (NHANES) from 2013 to 2014 was conducted. The periodontal examination was performed using a total oral periodontal examination program, and probe measurements were collected at six sites per tooth in NHANES. Severe periodontitis was characterized as: ≥ 2 interproximal sites with attachment loss (AL) ≥ 6 mm (not on the same tooth) and ≥ 1 interproximal site with probing depth (PD) ≥ 5 mm. Severe periodontitis and serum 25(OH)D were the dependent and independent variables, respectively. Univariate, multivariate, and subgroup analyses were performed to explore the relationship between severe periodontitis and serum 25(OH)D. RESULTS: Among the 2928 participants, the average age of the population was 50 ± 13.71 years old, with 1425 (48.67%) males, 316 (10.79%) exhibited severe periodontitis. Serum 25(OH)D showed a significantly negative association with severe periodontitis after adjusting all variables (OR 0.75, 95% CI 0.63-0.89). In addition, severe periodontitis has a nonlinear relationship with serum 25(OH)D, whoes inflection point was 102 (nmol/L). On the left side of the inflection point (25(OH)D ≤ 102 nmol/L), the effect size was 0.98 and 95%CI was 0.98-0.99 (25(OH)D per 1 nmol/L increments). On the right side of the inflection point (25(OH)D > 102 nmol/L), the effect size was 0.99 and 95% CI was 0.98-1.01. The subgroup analysis showed pronounced changes in non-Hispanic white, alcohol consumption, diabetes, and health insurance. CONCLUSION: Serum 25 (OH) D in relation to severe periodontitis is nonlinear in our study.When serum 25 (OH) D is less than 102 nmol/L, serum 25 (OH) D is negatively associated with severe periodontitis.


Assuntos
Periodontite , Qualidade de Vida , Adulto , Estudos Transversais , Humanos , Masculino , Pessoa de Meia-Idade , Inquéritos Nutricionais , Periodontite/complicações , Periodontite/epidemiologia , Vitamina D/análogos & derivados
5.
Nanotechnology ; 31(6): 065102, 2020 Jan 31.
Artigo em Inglês | MEDLINE | ID: mdl-31645027

RESUMO

Melittin (MEL), the primary active component of bee venom, has recently emerged as a promising cancer chemotherapeutic agent. However, the instability and rapid degradation of MEL is a significant challenge in practical therapeutic applications. In the present study, graphene oxide (GO)-based magnetic nanocomposites (PEG-GO-Fe3O4) were prepared and adopted as the drug delivery vehicles of MEL, and the anticancer effects of PEG-GO-Fe3O4/MEL complexes on human cervical cancer HeLa cells were studied. PEG-GO-Fe3O4 exhibited a series of unique physical and chemical properties resulting in multiple interactions with MEL, and ultimately the release of MEL. In vitro experiments showed that PEG-GO-Fe3O4/MEL not only distinctly enhanced the inhibition effect on HeLa cells, but also induced pore formation in the cell membrane that ultimately led to cell lysis. In this newly developed drug delivery system, PEGylated GO plays the role of a MEL protector while Fe3O4 nanoparticles act as magnetic responders; therefore active MEL can be released over a long period of time (up to 72 h) and maintain its inhibition effect on HeLa cells.


Assuntos
Grafite/química , Meliteno/farmacologia , Neoplasias do Colo do Útero/tratamento farmacológico , Proliferação de Células/efeitos dos fármacos , Sobrevivência Celular/efeitos dos fármacos , Sistemas de Liberação de Medicamentos , Estabilidade de Medicamentos , Feminino , Células HeLa , Humanos , Meliteno/química , Nanocompostos , Polietilenoglicóis/química
6.
AAPS PharmSciTech ; 18(1): 224-230, 2017 01 01.
Artigo em Inglês | MEDLINE | ID: mdl-26961968

RESUMO

The aim of this study was to prepare APAP crystals by cooling, anti-solvent, and solvent evaporation crystallization to enhance its dissolution rate and to make comparisons of the three methods. Agitating speeds and types were regarded as factors affecting crystallization procedure. Samples were made with different ratios of PEG4000. They were characterized by X-ray diffraction and scanning electron microscopy. Dissolution tests were conducted to assess their dissolution property. The proportions of carriers existing in crystals by cooling and anti-solvent crystallization ranged from 1.3 to 5.1%. Mean dissolution time (MDT) of samples by the two methods was about 3 min, which was 17.2 min for untreated APAP. Addition of too much PEG4000 in solvent evaporation crystallization could decrease dissolution rate of APAP. Samples agitated by a rotor with speed of 100, 500, and 1000 rpm dissolved faster than those by a high shear mixer with speed of 3400 and 5000 rpm or by a glass rod. Agitating speed and type could affect particle size and drug dissolution. Dissolution enhancement of APAP might be attributed to decrease of fine particles and increase of particle wettability.


Assuntos
Acetaminofen/química , Solventes/química , Cristalização/métodos , Microscopia Eletrônica de Varredura/métodos , Polietilenoglicóis/química , Solubilidade , Molhabilidade , Difração de Raios X/métodos
7.
J Mater Sci Mater Med ; 27(9): 139, 2016 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-27534399

RESUMO

This study aimed to evaluate the effects of Ti-Nb-Zr-Ta-Si alloy implants on mineral apposition rate and new BIC contact in rabbits. Twelve Ti-Nb-Zr-Ta-Si alloy implants were fabricated and placed into the right femur sites in six rabbits, and commercially pure titanium implants were used as controls in the left femur. Tetracycline and alizarin red were administered 3 weeks and 1 week before euthanization, respectively. At 4 weeks and 8 weeks after implantation, animals were euthanized, respectively. Surface characterization and implant-bone contact surface analysis were performed by using a scanning electron microscope and an energy dispersive X-ray detector. Mineral apposition rate was evaluated using a confocal laser scanning microscope. Toluidine blue staining was performed on undecalcified sections for histology and histomorphology evaluation. Scanning electron microscope and histomorphology observation revealed a direct contact between implants and bone of all groups. After a healing period of 4 weeks, Ti-Nb-Zr-Ta-Si alloy implants showed significantly higher mineral apposition rate compared to commercially pure titanium implants (P < 0.05), whereas there was no significant difference between Ti-Nb-Zr-Ta-Si alloy implants and commercially pure titanium implants (P > 0.05) at 8 weeks. No significant difference of bone-to-implant contact was observed between Ti-Nb-Zr-Ta-Si alloy implants and commercially pure titanium implants implants after a healing period of 4 weeks and 8 weeks. This study showed that Ti-Nb-Zr-Ta-Si alloy implants could establish a close direct contact comparedto commercially pure titanium implants implants, improved mineral matrix apposition rate, and may someday be an alternative as a material for dental implants.


Assuntos
Implantes Dentários , Nióbio/química , Osseointegração/efeitos dos fármacos , Silício/química , Tantálio/química , Titânio/química , Zircônio/química , Ligas , Animais , Antraquinonas/administração & dosagem , Fêmur , Implantes Experimentais , Microscopia Confocal , Microscopia Eletrônica de Varredura , Coelhos , Propriedades de Superfície , Tetraciclina/administração & dosagem , Raios X
8.
Nano Lett ; 13(4): 1649-54, 2013 Apr 10.
Artigo em Inglês | MEDLINE | ID: mdl-23465066

RESUMO

The first GaS nanosheet-based photodetectors are demonstrated on both mechanically rigid and flexible substrates. Highly crystalline, exfoliated GaS nanosheets are promising for optoelectronics due to strong absorption in the UV-visible wavelength region. Photocurrent measurements of GaS nanosheet photodetectors made on SiO2/Si substrates and flexible polyethylene terephthalate (PET) substrates exhibit a photoresponsivity at 254 nm up to 4.2 AW(-1) and 19.2 AW(-1), respectively, which exceeds that of graphene, MoS2, or other 2D material-based devices. Additionally, the linear dynamic range of the devices on SiO2/Si and PET substrates are 97.7 dB and 78.73 dB, respectively. Both surpass that of currently exploited InGaAs photodetectors (66 dB). Theoretical modeling of the electronic structures indicates that the reduction of the effective mass at the valence band maximum (VBM) with decreasing sheet thickness enhances the carrier mobility of the GaS nanosheets, contributing to the high photocurrents. Double-peak VBMs are theoretically predicted for ultrathin GaS nanosheets (thickness less than five monolayers), which is found to promote photon absorption. These theoretical and experimental results show that GaS nanosheets are promising materials for high-performance photodetectors on both conventional silicon and flexible substrates.


Assuntos
Gálio/química , Grafite/química , Nanopartículas/química , Luz , Polietilenotereftalatos/química , Silício/química , Dióxido de Silício/química , Especificidade por Substrato , Propriedades de Superfície
9.
ACS Nano ; 17(13): 12809-12819, 2023 07 11.
Artigo em Inglês | MEDLINE | ID: mdl-37338135

RESUMO

Similar to natural muscle fibers, coiled artificial muscle fibers provide a straightforward contraction. However, unlike natural muscle fibers, their recovery from the contracted state to the initial state requires high stress, resulting in almost zero work during a full actuation cycle. Herein, a self-recoverable coiled artificial muscle fiber was prepared by conformally coating an elastic carbon nanotube (CNT) fiber with a very thin liquid crystal elastomer (LCE) sheath. The as-obtained muscle fiber demonstrated excellent actuation properties comprising 56.9% contractile stroke, 1522%/s contraction rate, 7.03 kW kg-1 power density, and 32,000 stable cycles. The LCE chains were helically aligned in a nematic phase, and the phase change of the LCE caused by Joule heating drove the actuation process. Moreover, the LCE/CNT fiber had a well-separated, torsionally stable, and elastic coiled structure, which permitted large contractile strokes and acted as an elastic template for external-stress-free recovery. Thus, the use of self-recoverable muscle fibers to mimic the natural muscles for object dragging, multidirectional bending, and quick striking was demonstrated.


Assuntos
Cristais Líquidos , Nanotubos de Carbono , Fibras Musculares Esqueléticas , Elastômeros/química , Fibra de Carbono , Nanotubos de Carbono/química , Cristais Líquidos/química
10.
Biomed Mater ; 15(5): 055012, 2020 08 28.
Artigo em Inglês | MEDLINE | ID: mdl-32857733

RESUMO

Titanium (Ti) and its alloys are widely used in dental implants due to their favorable mechanical properties and biocompatibility. Surface characteristics, including physical and chemical properties, are crucial factors to enhance the osteogenesis performance of Ti. The aim of this study is to evaluate amino group surface modification to facilitate the osteogenic potential and bone repair of dental implants both in vitro and in vivo. Herein, amino group-modified Ti surfaces were constructed via the plasma-enhanced chemical vapor deposition (PECVD) technique with an allylamine monomer. The adhesion, proliferation, alkaline phosphate activity and osteogenesis-related genetic expression of MG-63 cells on the surfaces were performed in vitro and presented a significant increase in amino group-modified Ti compared with that in Ti. The in vivo study in miniature pigs was evaluated through micro-computed tomography analysis and histological evaluation, which exhibited enhanced new bone formation in amino group-modified Ti compared with that in Ti after implantation for 4, 8 and 12 weeks. Consequently, amino group surface modification with the PECVD technique may provide a promising modification method to enhance the osteogenesis performance of Ti implants.


Assuntos
Materiais Biocompatíveis/química , Osteogênese/efeitos dos fármacos , Titânio/química , Fosfatase Alcalina/metabolismo , Animais , Osso e Ossos/patologia , Adesão Celular , Linhagem Celular Tumoral , Proliferação de Células , Sobrevivência Celular , Materiais Revestidos Biocompatíveis/química , Implantes Dentários , Humanos , Técnicas In Vitro , Teste de Materiais , Microscopia Eletrônica de Varredura , Osseointegração , Osteoblastos/citologia , Próteses e Implantes , Propriedades de Superfície , Suínos , Porco Miniatura , Cicatrização , Microtomografia por Raio-X
11.
J Biomed Mater Res A ; 106(1): 265-271, 2018 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-28782282

RESUMO

The surface modification of titanium and its alloys with amino group plasma-enhanced chemical vapor deposition has been proven to enhance the performance of implants on initial osteoblast bioactivity in vitro. However, scarce information on the effect of this kind of surface modification on nerve regeneration exists. In this study, the surface chemistry of pure Ti disks and surface-modified disks was examined using X-ray photoelectron spectroscopy. Cell counting kit 8 assay, 4,6-diamidino-2-phenylindole staining, flow cytometry, and scanning electron microscopy showed that either the p30% or cw + p30% mode-mediated surface significantly promote Schwann cell adhesion without any cytotoxicity compared with the pure Ti surface, and the cw + p30% group showed the best performance on cell adhesion. However, results of polymerase chain reaction and Western blot analyses showed that the mRNA and protein levels of glial cell-derived neurotrophic factor and nerve growth factor of the p30% and cw + p30% groups were lower than those of the Ti group at some time points. Generally, the results indicate that amino-functionalized Ti surfaces can promote Schwann cell adhesion without cytotoxicity, but this modification, in fact, inhibited the expression of the key growth factors GDNF and NGF of Schwann cells. © 2017 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 106A: 265-271, 2018.


Assuntos
Aminas/química , Materiais Biocompatíveis/farmacologia , Plasma/química , Células de Schwann/efeitos dos fármacos , Titânio/química , Ligas/química , Aminas/análise , Animais , Materiais Biocompatíveis/química , Adesão Celular/efeitos dos fármacos , Linhagem Celular , Proliferação de Células/efeitos dos fármacos , Sobrevivência Celular/efeitos dos fármacos , Fator Neurotrófico Derivado de Linhagem de Célula Glial/antagonistas & inibidores , Heptanos/química , Fator de Crescimento Neural/antagonistas & inibidores , Regeneração Nervosa , Propriedades de Superfície
12.
Int J Nanomedicine ; 13: 7409-7426, 2018.
Artigo em Inglês | MEDLINE | ID: mdl-30519023

RESUMO

BACKGROUND AND PURPOSE: Nanoparticle-loaded hydrogels - localized drug delivery devices containing a combination of therapeutic nanoparticles and implantable hydrogel - have been recipients of increased focus and interest for cancer treatment. However, it is difficult for the released nanoparticles to penetrate deeply into tumors because of the dense collagen network in the tumor extracellular matrix, which greatly limits their antitumor effect. We hypothesized that the implantation of a hydrogel loaded with both nanoparticles and losartan (Los) might enhance penetration because Los has been proven to effectively reduce collagen levels in various tumors. Herein, we developed a nanoparticle/Los-loaded hydrogel system and evaluated the intratumoral distribution and anticancer effect after peritumoral implantation of nanoparticles. METHODS: Fluorescent polystyrene nanoparticles (FPNPs, size ~100 nm) and Los were simultaneously encapsulated in a polyethylene glycol (PEG) hydrogel to form the FPNP/Los-loaded hydrogel. After peritumoral implantation in 4T1 tumor-bearing mice for 2 weeks, intratumoral distributions of FPNPs and collagen level were determined. Based on the results, liposomal doxorubicin (Doxil, ~100 nm) was subsequently substituted for FPNPs in the hydrogel. The cellular uptake and cytotoxicity of the Doxil/Los-loaded hydrogel were studied, and the in vivo antitumor efficacy after peritumoral implantation was evaluated. RESULTS: Compared with a standard FPNP-loaded hydrogel, the FPNP/Los-loaded hydrogel resulted in enhanced penetration and reduced collagen levels after implantation. Thereafter, the potential of a Doxil/Los-loaded hydrogel for cancer treatment was studied. Doxorubicin was released from the hydrogel and induced effective cytotoxicity against 4T1 cells. The Doxil/Los-loaded hydrogel showed synergistic antitumor effects in 4T1 tumor-bearing mice and was more effective at tumor inhibition than the Doxil-loaded hydrogel. CONCLUSION: This study provides a proof of principle that the implantation of nanoparticles/Los-loaded hydrogel can increase the intratumoral distribution and antitumor efficacy of nanoparticles, owing to collagen depletion by Los. Future studies may build on this strategy for enhanced tumor penetration of nanoparticles.


Assuntos
Antineoplásicos/uso terapêutico , Hidrogéis/química , Implantes Experimentais , Losartan/química , Nanopartículas/química , Neoplasias/tratamento farmacológico , Animais , Antineoplásicos/farmacologia , Linhagem Celular Tumoral , Proliferação de Células/efeitos dos fármacos , Doxorrubicina/análogos & derivados , Doxorrubicina/farmacologia , Doxorrubicina/uso terapêutico , Endocitose , Fluorescência , Humanos , Camundongos Nus , Nanopartículas/ultraestrutura , Neoplasias/patologia , Tamanho da Partícula , Polietilenoglicóis/farmacologia , Polietilenoglicóis/uso terapêutico , Poliestirenos/química
13.
Medicine (Baltimore) ; 96(49): e9131, 2017 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-29245353

RESUMO

RATIONALE: Behcet's disease (BD) is a rare systemic vasculitis disorder that can involve vessels of any size. PATIENT CONCERNS: A 60-year-old female had recurrent painful mouth ulcers about 30 years ago and recently presented with abdominal distension, conjunctival congestion, and chest pain in sequence. DIAGNOSES: The patient was diagnosed with BD according to the International Criteria for Behcet's Disease (ICBD). INTERVENTIONS: A therapy of glucocorticoids and cyclophosphamide was administered. OUTCOMES: After a 3-month treatment, follow-up examination showed a depression of the inflammation and a slight decrease of the arterial aneurysms. LESSONS: BD patients may get a delayed diagnosis because of the long duration between the first and subsequent manifestations. Suspect patients should be followed-up and the diagnosis of BD should be considered when multiple tissues or organs are involved.


Assuntos
Aneurisma/etiologia , Síndrome de Behçet/complicações , Síndrome de Behçet/diagnóstico , Úlceras Orais/etiologia , Aneurisma/fisiopatologia , Síndrome de Behçet/tratamento farmacológico , Síndrome de Behçet/fisiopatologia , Feminino , Humanos , Imunossupressores/uso terapêutico , Pessoa de Meia-Idade , Úlceras Orais/fisiopatologia
14.
Biotechnol Prog ; 31(2): 387-95, 2015.
Artigo em Inglês | MEDLINE | ID: mdl-25641630

RESUMO

In this work, cephalosporin C acylase (CA), a heterodimeric enzyme of industrial potential in direct hydrolysis of cephalosporin C (CPC) to 7-aminocephalosporanic acid (7-ACA), was covalently immobilized on the aminated support LX1000-HA (HA) with two different protocols. The stability of CA adsorbed onto the HA support followed by crosslinking with glutaraldehyde (HA-CA-glut) was better than that of the CA covalently immobilized on the glutaraldehyde preactivated HA support (HA-glut-CA). The thermostabilization factors (compared with the free enzyme) of these two immobilized enzymes were 11.2-fold and 2.2-fold, respectively. In order to improve the stability of HA-CA-glut, a novel strategy based on postimmobilization modifying with aminated molecules was developed to take advantage of the glutaraldehyde moieties left on the enzyme and support. The macromolecules, such as polyethyleneimine (PEI) and chitosan, had larger effects than small molecules on the thermal stability of the immobilized enzyme perhaps due to crosslinking of the enzymes and support with each other. The quaternary structure of the CA could be much stabilized by this novel approach including physical adsorption on aminated support, glutaraldehyde treatment, and macromolecule modification. The HA-CA-glut-PEI20000 (the HA-CA-glut postmodified with PEI Mw = 20,000) had a thermostabilization factor of 20-fold, and its substrate affinity (Km = 14.3 mM) was better than that of HA-CA-glut (Km = 33.4 mM). The half-life of the immobilized enzymes HA-CA-glut-PEI20000 under the CPC-catalyzing conditions could reach 28 cycles, a higher value than that of HA-CA-glut (21 cycles).


Assuntos
Cefalosporinas/metabolismo , Reagentes de Ligações Cruzadas/química , Enzimas Imobilizadas/química , Glutaral/química , Penicilina Amidase/química , Polietilenoimina/química , Adsorção , Aminação , Reatores Biológicos , Estabilidade Enzimática , Enzimas Imobilizadas/metabolismo , Concentração de Íons de Hidrogênio , Penicilina Amidase/metabolismo , Temperatura
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