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2.
Front Psychiatry ; 14: 1183916, 2023.
Artigo em Inglês | MEDLINE | ID: mdl-37772066

RESUMO

Introduction: Family environment is the primary environment for adolescent growth and development, which is believed to have an important impact on the occurrence of non-suicidal self-injury (NSSI) behavior in adolescents. This study aimed to explore the effects of family environment cognition and cognitive differences perceived by adolescents and their parents on the treatment effects of NSSI in adolescents and to provide more potential perspectives for NSSI treatment. Methods: A one-year prospective longitudinal sub-cohort investigation was carried out among 199 adolescents engaged in NSSI and one of their important guardians from the Longitudinal Psychosomatic Disease Study (LoPDS). The NSSI behaviors of adolescents were evaluated at 3 months, 6 months and 1 year after enrollment. The family environment scale (FES) and NSSI Behavior Questionnaire were used as assessment tools for family environment and adolescents NSSI behaviors. Multiple linear regression was used to investigate the role of family environment perception difference in the treatment effect of adolescent NSSI. Results: After one year of follow-up, the perceived self-injury impulse score in recent 2 weeks, self-injury impulse frequency in recent 2 weeks, total number of self-injury in recent 2 weeks decreased significantly. The higher the adolescent family cohesion (Beta: 1.130, 95% CI: 0.886,1.373; p=0.032), parental family expressiveness (Beta: 0.818, 95% CI: 0.375,1.260; p=0.037) and parental family active-recreational orientation score (Beta: 0.609, 95% CI: 0.236,0.981; p=0.048), the better the treatment effect. However, higher adolescent family conflict (Beta: -0.838, 95% CI: -1.377,-0.298; p=0.024) were associated with lower treatment outcomes. The greater the cognitive difference between parents and adolescents in family cohesion (Beta: -1.307, 95% CI: -2.074,-0.539; p=0.014) and family conflict(Beta: -0.665, 95% CI: -0.919,-0.410; p=0.037), the worse the therapeutic effect of NSSI might be. Discussion: There were certain differences in the cognition of family relationships between parents and adolescents, and subjective family relationship cognition and cognitive differences had a significant effect on the treatment effect of NSSI in adolescents. Helping them identify the cause of cognitive differences and conducting systematic family therapy from the points of difference may be another perspective to improve the treatment effect of NSSI in adolescents.

3.
J Behav Ther Exp Psychiatry ; 81: 101883, 2023 12.
Artigo em Inglês | MEDLINE | ID: mdl-37290350

RESUMO

BACKGROUND AND OBJECTIVES: Understanding language features of depression contributes to the detection of the disorder. Considering that depression is characterized by dysfunctions in emotion and individuals with depression often show emotion-dependent cognition, the present study investigated the speech features and word use of emotion-dependent narrations in patients with depression. METHODS: Forty depression patients and forty controls were required to narrate self-relevant memories under five basic human emotions (i.e., sad, angry, fearful, neutral, and happy). Recorded speech and transcribed texts were analyzed. RESULTS: Patients with depression, as compared to non-depressed individuals, talked slower and less. They also performed differently in using negative emotion, work, family, sex, biology, health, and assent words regardless of emotion manipulation. Moreover, the use of words such as first person singular pronoun, past tense, causation, achievement, family, death, psychology, impersonal pronoun, quantifier and preposition words displayed emotion-dependent differences between groups. With the involvement of emotion, linguistic indicators associated with depressive symptoms were identified and explained 71.6% variances of depression severity. LIMITATIONS: Word use was analyzed based on the dictionary which does not cover all the words spoken in the memory task, resulting in text data loss. Besides, a relatively small number of depression patients were included in the present study and therefore the results need confirmation in future research using big emotion-dependent data of speech and texts. CONCLUSIONS: Our findings suggest that consideration of different emotional contexts is an effective means to improve the accuracy of depression detection via the analysis of word use and speech features.


Assuntos
Depressão , Idioma , Humanos , Emoções , Linguística , Ira
5.
J Affect Disord ; 318: 123-129, 2022 12 01.
Artigo em Inglês | MEDLINE | ID: mdl-36057290

RESUMO

BACKGROUND: Generalized anxiety disorder (GAD) and major depressive disorder (MDD) are both highly prevalent and comorbid psychiatric disorders. Neurocognitive dysfunction has been commonly found in MDD, but the findings in GAD are inconsistent. Few studies have directly compared cognitive performance between GAD and MDD. Therefore, the present study aimed to reveal the similar and distinct cognitive impairments between both disorders. METHODS: Three non-overlapping and non-comorbid groups were enrolled in the current study including patients with GAD (n = 37), MDD (n = 107) and healthy controls (n = 74). Levels of anxiety and depression were assessed using the Hamilton Anxiety Rating Scale (HAMA) and the Hamilton Depression Rating Scale (HAMD) respectively. The Cambridge Neuropsychological Test Automated Battery (CANTAB) was used to compare the cognitive performance, including sustained attention, visual memory, executive functions and learning. RESULTS: Both MDD and GAD groups demonstrated common significant deficits in sustained attention, visual memory, working memory and learning when compared to healthy controls. Despite the similarities, the MDD group had significantly greater impairment in learning, particularly generalization, while the GAD group demonstrated more pronounced deficits in visual memory. LIMITATIONS: Patients involved were medicated and the sample size for GAD was relatively small. CONCLUSIONS: The significant differences in visual memory and learning between MDD and GAD groups might be indicators to distinguishing both disorders. These results confirm that cognitive function is of great importance as a future target for treatment in order to improve wellbeing, quality of life and functionality in both GAD and MDD.


Assuntos
Transtorno Depressivo Maior , Transtornos de Ansiedade/complicações , Transtornos de Ansiedade/diagnóstico , Transtornos de Ansiedade/tratamento farmacológico , Depressão , Transtorno Depressivo Maior/complicações , Transtorno Depressivo Maior/psicologia , Humanos , Memória de Curto Prazo , Qualidade de Vida
6.
BMJ Open ; 12(8): e062664, 2022 08 29.
Artigo em Inglês | MEDLINE | ID: mdl-36038167

RESUMO

OBJECTIVES: The COVID-19 outbreak beginning in late 2019 has resulted in negative emotions among the public. However, many healthcare workers risked their lives by voluntarily travelling to the worst-hit area, Hubei Province, to support antipandemic work. This study explored the mental health changes in these healthcare workers and tried to discover the influencing factors. DESIGN: A longitudinal online survey was begun on 8 February 2020, using the snowball sampling method, and this first phase ended on 22 February 2020 (T1). The follow-up survey was conducted from 8 February to 22 February 2021 (T2). SETTING: Healthcare workers from outside of the Hubei area who went to the province to provide medical assistance. PARTICIPANTS: 963 healthcare workers who completed both surveys. MEASURES: Self-Rating Scale of Sleep (SRSS), Generalised Anxiety Scale (GAD-7) and 9-item Patient Health Questionnaire (PHQ-9). RESULTS: There were no significant differences in the SRSS scores or in the GAD-7 scores between T1 and T2 (t=0.994, 0.288; p>0.05). However, the PHQ-9 score at T2 was significantly higher than the score at T1 (t=-10.812, p<0.001). Through multiple linear regression analysis, we found that the following traits could predict higher GAD-7 and PHQ-9 scores at T2: male sex, single marital status, occupation of nurse, lower professional technical titles, healthcare workers having a history of psychosis, treating seriously ill patients, having relatively poor self-perceived health, caring for patients who died and having family members who had been infected with COVID-19. CONCLUSIONS: The results indicate that the depression levels of these special healthcare workers increased in the long term, and the initial demographics and experiences related to the pandemic played an important role in predicting their long-term poor mental health. In the future, more appropriate psychological decompression training should be provided for these special healthcare workers.


Assuntos
COVID-19 , Ansiedade/epidemiologia , COVID-19/epidemiologia , Depressão/epidemiologia , Surtos de Doenças , Pessoal de Saúde/psicologia , Nível de Saúde , Humanos , Masculino , Estudos Prospectivos , SARS-CoV-2
7.
J Affect Disord ; 303: 148-154, 2022 04 15.
Artigo em Inglês | MEDLINE | ID: mdl-35157948

RESUMO

BACKGROUND: Childhood maltreatment is significantly associated with greater occurrence of mental disorders in adulthood such as depression and anxiety. As a key node of the limbic system, the amygdala is engaged in emotional processing and regulation and is dysfunctional in many psychiatric disorders. The present study aimed at exploring the association between childhood maltreatment and amygdala-based functional networks and their potential contributions to depression and anxiety. METHODS: Totally 90 Chinese healthy volunteers participated in a resting-state fMRI experiment. Levels of childhood maltreatment experience were assessed using the Childhood Trauma Questionnaire (CTQ-SF) as well as levels of depression and anxiety. Associations between CTQ-SF scores and bilateral amygdala gray matter volume and resting-state functional connectivity (RSFC) of the amygdala and selected regions of interest were analyzed using multiple regression analyses with sex and age as covariates. A subsequent moderation analysis was performed to identify whether associations were predictive of depression and anxiety levels. RESULTS: Childhood maltreatment was significantly negatively associated with RSFC between left amygdala and anterior insula. Further sub-region analyses revealed that this negative association only occurred for the left centromedial amygdala subregion, which subsequently moderated the relationship between levels of childhood emotional abuse and depression / anxiety. LIMITATIONS: No psychiatric patients were involved and specific neural associations with different childhood maltreatment subtypes need to be examined in future studies. CONCLUSION: The present findings provide evidence for altered RSFC of centromedial amygdala and the anterior insula associated with childhood maltreatment and which moderate levels of depression and anxiety in adulthood.


Assuntos
Depressão , Abuso Emocional , Adulto , Tonsila do Cerebelo/diagnóstico por imagem , Ansiedade/diagnóstico por imagem , Transtornos de Ansiedade/diagnóstico por imagem , Depressão/diagnóstico por imagem , Humanos , Imageamento por Ressonância Magnética
9.
Front Public Health ; 10: 1019703, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-36699872

RESUMO

Introduction: The COVID-19 pandemic is ongoing, and the world continues to work to defeat it. We designed this study to understand the longitudinal change in the mental health of residents who experienced the initial disease outbreak in China and to explore the long-term influencing factors. Methods: The Perceived Stress Scale (PSS), Generalized Anxiety Scale (GAD-7), and Patient Health Questionnaire-9 (PHQ-9) were administered to the same sample four times: during the initial outbreak (T1), 1 month later (T2), 18 months later (T3), and 26 months later (T4). Results: A total of 397 participants completed all of the follow ups. The mean PSS scores among the four time points showed significant differences (F = 183.98, P < 0.001), with the highest score at T1 (15.35 ± 7.14), a sharp decline at T2 (11.27 ± 6.27), an obvious rebound at T3 (15.17 ± 7.46), and finally a slight decrease at T4 (14.41 ± 7.99). Among the four mean GAD-7 scores, significant differences were also found (F = 242.0, P < 0.001), with the trend that from T1 (7.42 ± 6.03) to T2 (7.35 ± 5.88), the scores remained steady, while they showed an apparent decline at T3 (5.00 ± 5.30) and no obvious change at T4 (4.91 ± 4.81). There were no significant differences among the mean PHQ-9 scores (F = 1.256, P < 0.284). The long-term influencing factors differed for stress, anxiety and depression, but all three were influenced by a history of psychosis at T4, quarantine status and whether the participants' family members were infected during the initial outbreak. Discussion: The survey revealed that repeated outbreaks in other areas also had an impact on those who experienced the initial outbreak, with a return of stress, a decline in anxiety, and no change in depression, which provides direction for interventions in the future.


Assuntos
COVID-19 , Humanos , COVID-19/epidemiologia , Saúde Mental , Pandemias , Estudos Longitudinais , Depressão/epidemiologia , Depressão/psicologia , Surtos de Doenças , China/epidemiologia
10.
Front Psychiatry ; 12: 743526, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-34955911

RESUMO

Non-suicidal self-injury (NSSI) in adolescents hospitalized with psychiatric disorders continues to increase after the outbreak of COVID-19. This study aimed to explore the relationship between the pandemic and NSSI among adolescents and whether the composition of psychosocial factors related to NSSI has changed during the pandemic. Through the retrospective analysis of medical records retrieved from the electronic system of the psychiatric hospital located in Chengdu from January 2016 to March 2021, 609 medical records of adolescents were obtained. The main potential psychosocial factors were determined by deductive content analysis. Among the 609 adolescents, 420 subjects had engaged in NSSI, while 189 did not. We found that the percentage of adolescents who had engaged in NSSI in 2016 was only 29.2%, reaching 34.5% in 2017, 45.7% in 2018, 61.3% in 2019, 92.5% in 2020, and 95.9% in 2021. In the binary logistic regression model, female sex (OR = 0.073, 95% CI: 0.028-0.186), older age (OR = 1.234, 95% CI: 1.030-1.478), having a single parent (OR = 7.865, 95% CI: 3.997-15.476), having experienced trauma (OR = 2.192, 95% CI: 1.032-4.654), having experienced social isolation from peers (OR = 8.139, 95% CI: 4.037-16.408), having experienced body-focused bullying (OR = 3.078, 95% CI: 1.295-7.318), overuse of a mobile phone in the parents' opinions (OR = 4.354, 95% CI: 1.380-13.738), having attempted suicide (OR = 9.120, 95% CI: 4.492-18.512), and during the pandemic (time point is January 30, 2020) (OR = 5.399, 95% CI: 1.679-17.357) were the factors that were significantly associated with NSSI. When comparing the differences in psychosocial factors between the pre-pandemic and the during-pandemic groups, the results showed that the family constitution, parent-child relationships, mobile phone overuse, and stressful learning were important factors. Tailored interventions geared towards changed psychosocial factors should be formulated.

11.
BMC Public Health ; 21(1): 809, 2021 04 28.
Artigo em Inglês | MEDLINE | ID: mdl-33906613

RESUMO

BACKGROUND: As the outbreak of COVID-19, traditional face-to-face psychological intervention are difficult to achieve, so hotline becomes available and recommended strategies. The callers' characteristic could help us to study their experiences of emotional distress, as well as the reasons for calling during the pandemic, which can be used to inform future service design and delivery. METHODS: The information of 1558 callers called our hospital' s hotline for help from February 3, 2020, to March 16, 2020 were collected in the form of Tick-box and Free text, and the inductive content analysis was undertaken focusing on the reasons for caller engagement. RESULTS: It was indicated that more than half of the callers are female (59.7%), mostly between the age of 18-59 (76.5%). The average age was 37.13 ± 13.76 years old. The average duration of a call to the hotline was 10.03 ± 9.84 min. The most frequent description emotional state were anxious (45.1%) and calm (30.3%), with the sub-sequence of scared (18.2%), sad (11.9%), and angry (6.9%). All callers displayed a wide range of reasons for calling, with needing support around their emotion (64.6%), seeking practical help (44.0%), and sleep problems (20.3%) constituting the majority of calls. Among the subthemes, 314 callers thought the epidemic has made them upset, 198 asked questions about the epidemic, and 119 reported their life routines were disrupted. The prevalence of key reasons does not appear to differ over time. Through their feedback, 79.1% agreed that they felt emotionally better after calling, and 95.0% agreed that hotline had helped them. CONCLUSIONS: During the epidemic, the most concern of the public is still related to epidemics and its adverse effects. Fortunately, the hotline can be an active and effective rescue measure after an emergency happened.


Assuntos
COVID-19 , Linhas Diretas , Adulto , China/epidemiologia , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Pandemias , SARS-CoV-2 , Adulto Jovem
12.
Bioorg Med Chem Lett ; 30(7): 126969, 2020 04 01.
Artigo em Inglês | MEDLINE | ID: mdl-32014384

RESUMO

In this work, according to the 'me-too me-better' design strategy, a peculiar side chain different from lefamulin at C14 position of pleuromutilin was introduced. A series of novel thioether pleuromutilin derivatives containing cyclohexane in the C14 chain was synthesized by ten-step synthesis reaction. All derivatives were characterized by Nuclear Magnetic Resonance (NMR) and High Resolution Mass Spectrometer (HRMS). Furthermore, majority of derivatives displayed moderate antibacterial activity in vitro. However, the compound 2C and 2J exhibited comparable or superior antibacterial activity to lefamulin. The summarized structure-activity relationship not only made the variety of pleuromutilin derivatives more diverse, but also provided new ideas for its design and development.


Assuntos
Antibacterianos/farmacologia , Diterpenos/farmacologia , Compostos Policíclicos/farmacologia , Antibacterianos/síntese química , Diterpenos/síntese química , Desenho de Fármacos , Staphylococcus aureus Resistente à Meticilina/efeitos dos fármacos , Testes de Sensibilidade Microbiana , Estrutura Molecular , Compostos Policíclicos/síntese química , Staphylococcus epidermidis/efeitos dos fármacos , Relação Estrutura-Atividade , Pleuromutilinas
13.
Chem Biodivers ; 16(2): e1800560, 2019 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-30467968

RESUMO

A series of novel thioether or sulfoxide-type pleuromutilin derivatives containing heteroaromatic substituents at the end of C14 side chain were designed and synthesized. All of the derivatives were evaluated for their in vitro antibacterial activity. Some of them showed good to excellent antibacterial activity comparable to retapamulin and azamulin in most of the tested Gram-positive pathogens. In this work, a five-membered heterocyclic moiety, a pyrimidine-heterocyclic moiety, or a benzoheterocyclic moiety was introduced in the C14 side chain to increase the structural diversity of the pleuromutilin derivatives. The antibacterial results reveal that the thioether-containing pleuromutilin derivatives exert a more potency activity than the sulfoxide-type derivatives against Gram-positive pathogens. The structure-activity relationship summarized in this work may provide with some interesting clues as to which functionalities are beneficial for high antimicrobial activity of the pleuromutilin derivatives.


Assuntos
Antibacterianos/síntese química , Antibacterianos/farmacologia , Diterpenos/química , Diterpenos/farmacologia , Bactérias Gram-Positivas/efeitos dos fármacos , Testes de Sensibilidade Microbiana , Compostos Policíclicos , Relação Estrutura-Atividade , Sulfetos , Sulfóxidos , Pleuromutilinas
14.
Bioorg Med Chem Lett ; 29(3): 357-361, 2019 02 01.
Artigo em Inglês | MEDLINE | ID: mdl-30580917

RESUMO

The design, synthesis and SAR study of a new series of HIV-1 protease inhibitors with pentacyclic triterpenoids as P2 ligands and phenylsulfonamide as P2' ligands were discussed. These compounds exhibited micromolar inhibitory potency, among which compound T1c displayed HIV-1 protease inhibition with IC50 values of 0.12 µM, which was 67 times the inhibitory activity of its raw material Ursolic acid (8.0 µM).


Assuntos
Fármacos Anti-HIV/farmacologia , Desenho de Fármacos , Inibidores da Protease de HIV/farmacologia , Protease de HIV/metabolismo , Triterpenos Pentacíclicos/farmacologia , Sulfonamidas/farmacologia , Fármacos Anti-HIV/síntese química , Fármacos Anti-HIV/química , Relação Dose-Resposta a Droga , Inibidores da Protease de HIV/síntese química , Inibidores da Protease de HIV/química , HIV-1/efeitos dos fármacos , Humanos , Ligantes , Testes de Sensibilidade Microbiana , Estrutura Molecular , Triterpenos Pentacíclicos/síntese química , Triterpenos Pentacíclicos/química , Relação Estrutura-Atividade , Sulfonamidas/síntese química , Sulfonamidas/química
15.
Structure ; 19(12): 1773-83, 2011 Dec 07.
Artigo em Inglês | MEDLINE | ID: mdl-22153500

RESUMO

[NiFe]-hydrogenases are multimeric proteins. The large subunit contains the NiFe(CN)(2)CO bimetallic active center and the small subunit contains Fe-S clusters. Biosynthesis and assembly of the NiFe(CN)(2)CO active center requires six Hyp accessory proteins. The synthesis of the CN(-) ligands is catalyzed by the combined actions of HypF and HypE using carbamoylphosphate as a substrate. We report the structure of Escherichia coli HypF(92-750) lacking the N-terminal acylphosphatase domain. HypF(92-750) comprises the novel Zn-finger domain, the nucleotide-binding YrdC-like domain, and the Kae1-like universal domain, also binding a nucleotide and a Zn(2+) ion. The two nucleotide-binding sites are sequestered in an internal cavity, facing each other and separated by ∼14 Å. The YrdC-like domain converts carbamoyl moiety to a carbamoyl adenylate intermediate, which is channeled to the Kae1-like domain. Mutations within either nucleotide-binding site compromise hydrogenase maturation but do not affect the carbamoylphosphate phosphatase activity.


Assuntos
Carboxil e Carbamoil Transferases/química , Proteínas de Escherichia coli/química , Hidrolases Anidrido Ácido/química , Hidrolases Anidrido Ácido/metabolismo , Sítios de Ligação , Carbamoil-Fosfato/metabolismo , Carboxil e Carbamoil Transferases/metabolismo , Catálise , Domínio Catalítico , Escherichia coli/enzimologia , Escherichia coli/metabolismo , Proteínas de Escherichia coli/metabolismo , Hidrogenase/química , Ligantes , Acilfosfatase
16.
J Bacteriol ; 191(24): 7614-9, 2009 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-19801413

RESUMO

The MnmE-MnmG complex is involved in tRNA modification. We have determined the crystal structure of Escherichia coli MnmG at 2.4-A resolution, mutated highly conserved residues with putative roles in flavin adenine dinucleotide (FAD) or tRNA binding and MnmE interaction, and analyzed the effects of these mutations in vivo and in vitro. Limited trypsinolysis of MnmG suggests significant conformational changes upon FAD binding.


Assuntos
Proteínas de Bactérias/química , Proteínas de Bactérias/metabolismo , Proteínas de Escherichia coli/química , Proteínas de Escherichia coli/metabolismo , Escherichia coli/enzimologia , RNA de Transferência/metabolismo , Regulação Alostérica , Proteínas de Bactérias/genética , Cristalografia por Raios X , Proteínas de Escherichia coli/genética , Flavina-Adenina Dinucleotídeo/metabolismo , Modelos Moleculares , Mutagênese Sítio-Dirigida , Proteínas Mutantes/genética , Proteínas Mutantes/metabolismo , Ligação Proteica , Estrutura Terciária de Proteína , Tripsina/metabolismo
17.
J Mol Biol ; 359(5): 1249-60, 2006 Jun 23.
Artigo em Inglês | MEDLINE | ID: mdl-16678853

RESUMO

Polyphosphate (polyP) is a linear polymer consisting of tens to hundreds of phosphate molecules joined together by high-energy anhydride bonds. These polymers are found in virtually all prokaryotic and eukaryotic cells and perform many functions; prominent among them are the responses to many stresses. Polyphosphate is synthesized by polyP kinase (PPK), using the terminal phosphate of ATP as the substrate, and degraded to inorganic phosphate by both endo- and exopolyphosphatases. Here we report the crystal structure and analysis of the polyphosphate phosphatase PPX from Escherichia coli O157:H7 refined at 2.2 Angstroms resolution. PPX is made of four domains. Domains I and II display structural similarity with one another and share the ribonuclease-H-like fold. Domain III bears structural similarity to the N-terminal, HD domain of SpoT. Domain IV, the smallest domain, has structural counterparts in cold-shock associated RNA-binding proteins but is of unknown function in PPX. The putative PPX active site is located at the interface between domains I and II. In the crystal structure of PPX these two domains are close together and represent the "closed" state. Comparison with the crystal structure of PPX/GPPA from Aquifex aeolicus reveals close structural similarity between domains I and II of the two enzymes, with the PPX/GPPA representing an "open" state. A striking feature of the dimer is a deep S-shaped canyon extending along the dimer interface and lined with positively charged residues. The active site region opens to this canyon. We postulate that this is a likely site of polyP binding.


Assuntos
Hidrolases Anidrido Ácido/química , Hidrolases Anidrido Ácido/metabolismo , Escherichia coli O157/enzimologia , Polifosfatos/metabolismo , Sequência de Aminoácidos , Sítios de Ligação , Dimerização , Metais/metabolismo , Modelos Moleculares , Dados de Sequência Molecular , Estrutura Terciária de Proteína , Alinhamento de Sequência
18.
J Biol Chem ; 281(22): 15525-35, 2006 Jun 02.
Artigo em Inglês | MEDLINE | ID: mdl-16565082

RESUMO

Heparinase II depolymerizes heparin and heparan sulfate glycosaminoglycans, yielding unsaturated oligosaccharide products through an elimination degradation mechanism. This enzyme cleaves the oligosaccharide chain on the nonreducing end of either glucuronic or iduronic acid, sharing this characteristic with a chondroitin ABC lyase. We have determined the first structure of a heparin-degrading lyase, that of heparinase II from Pedobacter heparinus (formerly Flavobacterium heparinum), in a ligand-free state at 2.15 A resolution and in complex with a disaccharide product of heparin degradation at 2.30 A resolution. The protein is composed of three domains: an N-terminal alpha-helical domain, a central two-layered beta-sheet domain, and a C-terminal domain forming a two-layered beta-sheet. Heparinase II shows overall structural similarities to the polysaccharide lyase family 8 (PL8) enzymes chondroitin AC lyase and hyaluronate lyase. In contrast to PL8 enzymes, however, heparinase II forms stable dimers, with the two active sites formed independently within each monomer. The structure of the N-terminal domain of heparinase II is also similar to that of alginate lyases from the PL5 family. A Zn2+ ion is bound within the central domain and plays an essential structural role in the stabilization of a loop forming one wall of the substrate-binding site. The disaccharide binds in a long, deep canyon formed at the top of the N-terminal domain and by loops extending from the central domain. Based on structural comparison with the lyases from the PL5 and PL8 families having bound substrates or products, the disaccharide found in heparinase II occupies the "+1" and "+2" subsites. The structure of the enzyme-product complex, combined with data from previously characterized mutations, allows us to propose a putative chemical mechanism of heparin and heparan-sulfate degradation.


Assuntos
Bacteroidetes/enzimologia , Polissacarídeo-Liases/química , Bacteroidetes/genética , Sequência de Bases , Domínio Catalítico , Clonagem Molecular , Cristalografia por Raios X , DNA Bacteriano/genética , Dissacarídeos/química , Dissacarídeos/metabolismo , Glicosilação , Ligação de Hidrogênio , Ligantes , Modelos Moleculares , Polissacarídeo-Liases/genética , Polissacarídeo-Liases/metabolismo , Conformação Proteica , Estrutura Terciária de Proteína , Proteínas Recombinantes/química , Proteínas Recombinantes/genética , Proteínas Recombinantes/metabolismo , Eletricidade Estática
19.
J Biol Chem ; 281(13): 8907-16, 2006 Mar 31.
Artigo em Inglês | MEDLINE | ID: mdl-16421095

RESUMO

Helicobacter pylori flagellin is heavily glycosylated with the novel sialic acid-like nonulosonate, pseudaminic acid (Pse). The glycosylation process is essential for assembly of functional flagellar filaments and consequent bacterial motility. Because motility is a key virulence factor for this and other important pathogens, the Pse biosynthetic pathway offers potential for novel therapeutic targets. From recent NMR analyses, we determined that the conversion of UDP-alpha-D-Glc-NAc to the central intermediate in the pathway, UDP-4-amino-4,6-dideoxy-beta-L-AltNAc, proceeds by formation of UDP-2-acetamido-2,6-dideoxy-beta-L-arabino-4-hexulose by the dehydratase/epimerase PseB (HP0840) followed with amino transfer by the aminotransferase, PseC (HP0366). The central role of PseC in the H. pylori Pse biosynthetic pathway prompted us to determine crystal structures of the native protein, its complexes with pyridoxal phosphate alone and in combination with the UDP-4-amino-4,6-dideoxy-beta-L-AltNAc product, the latter being converted to the external aldimine form in the active site of the enzyme. In the binding site, the AltNAc sugar ring adopts a 4C1 chair conformation, which is different from the predominant 1C4 form found in solution. The enzyme forms a homodimer where each monomer contributes to the active site, and these structures have permitted the identification of key residues involved in stabilization, and possibly catalysis, of the beta-L-arabino intermediate during the amino transfer reaction. The essential role of Lys183 in the catalytic event was confirmed by site-directed mutagenesis. This work presents for the first time a nucleotide-sugar aminotransferase co-crystallized with its natural ligand, and, in conjunction with the recent functional characterization of this enzyme, these results will assist in elucidating the aminotransferase reaction mechanism within the Pse biosynthetic pathway.


Assuntos
Proteínas de Bactérias/química , Proteínas de Bactérias/metabolismo , Flagelos/metabolismo , Helicobacter pylori/enzimologia , Transaminases/química , Transaminases/metabolismo , Sequência de Aminoácidos , Proteínas de Bactérias/genética , Sítios de Ligação , Catálise , Cristalografia por Raios X , Dimerização , Eletroforese Capilar , Eletroforese em Gel de Poliacrilamida , Glicosilação , Helicobacter pylori/genética , Helicobacter pylori/crescimento & desenvolvimento , Ligação de Hidrogênio , Interações Hidrofóbicas e Hidrofílicas , Cinética , Ligantes , Luz , Lisina/metabolismo , Modelos Biológicos , Modelos Moleculares , Estrutura Molecular , Mutagênese Insercional , Mutação , Ligação Proteica , Conformação Proteica , Estrutura Secundária de Proteína , Estrutura Terciária de Proteína , Subunidades Proteicas/química , Fosfato de Piridoxal/metabolismo , Espalhamento de Radiação , Análise Espectral Raman , Especificidade por Substrato , Transaminases/isolamento & purificação
20.
J Biol Chem ; 280(52): 42919-28, 2005 Dec 30.
Artigo em Inglês | MEDLINE | ID: mdl-16253988

RESUMO

Coenzyme A transferases are involved in a broad range of biochemical processes in both prokaryotes and eukaryotes, and exhibit a diverse range of substrate specificities. The YdiF protein from Escherichia coli O157:H7 is an acyl-CoA transferase of unknown physiological function, and belongs to a large sequence family of CoA transferases, present in bacteria to humans, which utilize oxoacids as acceptors. In vitro measurements showed that YdiF displays enzymatic activity with short-chain acyl-CoAs. The crystal structures of YdiF and its complex with CoA, the first co-crystal structure for any Family I CoA transferase, have been determined and refined at 1.9 and 2.0 A resolution, respectively. YdiF is organized into tetramers, with each monomer having an open alpha/beta structure characteristic of Family I CoA transferases. Co-crystallization of YdiF with a variety of CoA thioesters in the absence of acceptor carboxylic acid resulted in trapping a covalent gamma-glutamyl-CoA thioester intermediate. The CoA binds within a well defined pocket at the N- and C-terminal domain interface, but makes contact only with the C-terminal domain. The structure of the YdiF complex provides a basis for understanding the different catalytic steps in the reaction of Family I CoA transferases.


Assuntos
Coenzima A-Transferases/química , Coenzima A/química , Cristalografia por Raios X/métodos , Proteínas de Escherichia coli/química , Escherichia coli/enzimologia , Ésteres/química , Ácido Glutâmico/química , Sítios de Ligação , Ácidos Carboxílicos/química , Catálise , Domínio Catalítico , Cromatografia em Gel , Clonagem Molecular , Coenzima A-Transferases/metabolismo , Cristalização , Escherichia coli/metabolismo , Proteínas de Escherichia coli/metabolismo , Histidina/química , Espectrometria de Massas , Modelos Químicos , Modelos Moleculares , Conformação Molecular , Conformação Proteica , Dobramento de Proteína , Estrutura Quaternária de Proteína , Estrutura Secundária de Proteína , Estrutura Terciária de Proteína
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