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1.
J Bone Miner Res ; 38(1): 14-25, 2023 01.
Artigo em Inglês | MEDLINE | ID: mdl-36271471

RESUMO

Conventional therapy for hypoparathyroidism consisting of active vitamin D and calcium aims to alleviate hypocalcemia but fails to restore normal parathyroid hormone (PTH) physiology. PTH replacement therapy is the ideal physiologic treatment for hypoparathyroidism. The double-blind, placebo-controlled, 26-week, phase 3 PaTHway trial assessed the efficacy and safety of PTH replacement therapy for hypoparathyroidism individuals with the investigational drug TransCon PTH (palopegteriparatide). Participants (n = 84) were randomized 3:1 to once-daily TransCon PTH (initially 18 µg/d) or placebo, both co-administered with conventional therapy. The study drug and conventional therapy were titrated according to a dosing algorithm guided by serum calcium. The composite primary efficacy endpoint was the proportion of participants at week 26 who achieved normal albumin-adjusted serum calcium levels (8.3-10.6 mg/dL), independence from conventional therapy (requiring no active vitamin D and ≤600 mg/d of calcium), and no increase in study drug over 4 weeks before week 26. Other outcomes of interest included health-related quality of life measured by the 36-Item Short Form Survey (SF-36), hypoparathyroidism-related symptoms, functioning, and well-being measured by the Hypoparathyroidism Patient Experience Scale (HPES), and urinary calcium excretion. At week 26, 79% (48/61) of participants treated with TransCon PTH versus 5% (1/21) wiplacebo met the composite primary efficacy endpoint (p < 0.0001). TransCon PTH treatment demonstrated a significant improvement in all key secondary endpoint HPES domain scores (all p < 0.01) and the SF-36 Physical Functioning subscale score (p = 0.0347) compared with placebo. Additionally, 93% (57/61) of participants treated with TransCon PTH achieved independence from conventional therapy. TransCon PTH treatment normalized mean 24-hour urine calcium. Overall, 82% (50/61) treated with TransCon PTH and 100% (21/21) wiplacebo experienced adverse events; most were mild (46%) or moderate (46%). No study drug-related withdrawals occurred. In conclusion, TransCon PTH maintained normocalcemia while permitting independence from conventional therapy and was well-tolerated in individuals with hypoparathyroidism. © 2022 The Authors. Journal of Bone and Mineral Research published by Wiley Periodicals LLC on behalf of American Society for Bone and Mineral Research (ASBMR).


Assuntos
Hipoparatireoidismo , Hormônio Paratireóideo , Humanos , Hormônio Paratireóideo/efeitos adversos , Cálcio , Qualidade de Vida , Vitamina D , Terapia de Reposição Hormonal/efeitos adversos , Cálcio da Dieta , Minerais
2.
J Clin Endocrinol Metab ; 107(7): e2680-e2689, 2022 06 16.
Artigo em Inglês | MEDLINE | ID: mdl-35428884

RESUMO

PURPOSE: The objectives of the ongoing, Phase 3, open-label extension trial enliGHten are to assess the long-term safety and efficacy of weekly administered long-acting growth hormone lonapegsomatropin in children with growth hormone deficiency. METHODS: Eligible subjects completing a prior Phase 3 lonapegsomatropin parent trial (heiGHt or fliGHt) were invited to participate. All subjects were treated with lonapegsomatropin. Subjects in the United States switched to the TransCon hGH Auto-Injector when available. Endpoints were long-term safety, annualized height velocity, pharmacodynamics [insulin-like growth factor-1 SD score (SDS) values], and patient- and caregiver-reported assessments of convenience and tolerability. RESULTS: Lonapegsomatropin treatment during enliGHten was associated with continued improvements in height SDS through week 104 in treatment-naïve subjects from the heiGHt trial (-2.89 to -1.37 for the lonapegsomatropin group; -3.0 to -1.52 for the daily somatropin group). Height SDS also continued to improve among switch subjects from the fliGHt trial (-1.42 at fliGHt baseline to -0.69 at week 78). After 104 weeks, the average bone age/chronological age ratio for each treatment group was 0.8 (0.1), showing only minimal advancement of bone age relative to chronological age with continued lonapegsomatropin treatment among heiGHt subjects. Fewer local tolerability reactions were reported with the TransCon hGH Auto-Injector compared with syringe/needle. CONCLUSIONS: Treatment with lonapegsomatropin continued to be safe and well-tolerated, with no new safety signals identified. Children treated with once-weekly lonapegsomatropin showed continued improvement of height SDS through the second year of therapy without excess advancement of bone age.


Assuntos
Nanismo Hipofisário , Hormônio do Crescimento Humano , Estatura , Criança , Transtornos do Crescimento/tratamento farmacológico , Hormônio do Crescimento , Hormônio do Crescimento Humano/efeitos adversos , Humanos
3.
Orthop J Sports Med ; 10(1): 23259671211059216, 2022 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-35083358

RESUMO

BACKGROUND: Previously studied risk factors for sports-related concussion in soccer players include sex, age, and player position. However, prior studies were limited in number, they reported conflicting results, and most did not assess initial concussion severity. PURPOSE/HYPOTHESIS: The purpose of this study was to conduct an in-depth analysis of soccer players across key demographic groups (sex, age, position) for both concussion incidence and severity. It was hypothesized that concussion incidence and severity would be higher among male players, players aged ≥17 years, and goalkeepers. STUDY DESIGN: Cohort study; Level of evidence, 3. METHODS: The authors analyzed baseline and postinjury ImPACT (Immediate Post-Concussion Assessment and Cognitive Testing) scores for athletes aged 12 to 22 years between July 2009 and June 2019. Players were assigned to an age group based on when they had their most recent baseline test. Concussion incidence and concussion severity index were compared using t tests and multivariate logistic regression. RESULTS: For 1189 individuals who reported soccer as their primary sport, 1032 contributed 1754 baseline ImPACT tests (some individuals had multiple baseline tests), whereas 445 individuals were suspected of sustaining a concussion and then referred for a postinjury 1 test. Of these players, 254 (24.6%) had both a baseline and a postinjury test and were analyzed for concussion severity. Linear regression showed that forwards had a lower incidence of ImPACT-proxied concussions than goalkeepers had (P = .008). Female players had a significantly higher incidence of ImPACT concussions compared with male players (mean, 0.07 [female] vs 0.04 [male] concussions per person-year; P = .05). Players in the ≥17-year age group had a higher incidence of ImPACT concussions than players in the 15- to 16-year age group (P = .04), although the 15- to 16-year age group had more severe concussions than the ≥17-year age group (mean severity index, 2.91 [age 15-16 years] vs 1.73 [age ≥17 years]; P = .001). CONCLUSION: Female soccer players experienced a higher incidence of concussion than did male players, and goalkeepers experienced a greater incidence of ImPACT concussions than did forwards. Players of both sexes and all positions in the 15- to 16-year age group showed increased initial concussion severity compared with the ≥17-year age group, despite a lower comparative incidence of ImPACT concussions. Further study is needed to understand whether sex and player position affect concussion severity.

4.
Ann Oncol ; 30(4): 597-603, 2019 04 01.
Artigo em Inglês | MEDLINE | ID: mdl-30891595

RESUMO

BACKGROUND: Noninvasive genotyping using plasma cell-free DNA (cfDNA) has the potential to obviate the need for some invasive biopsies in cancer patients while also elucidating disease heterogeneity. We sought to develop an ultra-deep plasma next-generation sequencing (NGS) assay for patients with non-small-cell lung cancers (NSCLC) that could detect targetable oncogenic drivers and resistance mutations in patients where tissue biopsy failed to identify an actionable alteration. PATIENTS AND METHODS: Plasma was prospectively collected from patients with advanced, progressive NSCLC. We carried out ultra-deep NGS using cfDNA extracted from plasma and matched white blood cells using a hybrid capture panel covering 37 lung cancer-related genes sequenced to 50 000× raw target coverage filtering somatic mutations attributable to clonal hematopoiesis. Clinical sensitivity and specificity for plasma detection of known oncogenic drivers were calculated and compared with tissue genotyping results. Orthogonal ddPCR validation was carried out in a subset of cases. RESULTS: In 127 assessable patients, plasma NGS detected driver mutations with variant allele fractions ranging from 0.14% to 52%. Plasma ddPCR for EGFR or KRAS mutations revealed findings nearly identical to those of plasma NGS in 21 of 22 patients, with high concordance of variant allele fraction (r = 0.98). Blinded to tissue genotype, plasma NGS sensitivity for de novo plasma detection of known oncogenic drivers was 75% (68/91). Specificity of plasma NGS in those who were driver-negative by tissue NGS was 100% (19/19). In 17 patients with tumor tissue deemed insufficient for genotyping, plasma NGS identified four KRAS mutations. In 23 EGFR mutant cases with acquired resistance to targeted therapy, plasma NGS detected potential resistance mechanisms, including EGFR T790M and C797S mutations and ERBB2 amplification. CONCLUSIONS: Ultra-deep plasma NGS with clonal hematopoiesis filtering resulted in de novo detection of targetable oncogenic drivers and resistance mechanisms in patients with NSCLC, including when tissue biopsy was inadequate for genotyping.


Assuntos
Biomarcadores Tumorais/genética , Carcinoma Pulmonar de Células não Pequenas/genética , DNA Tumoral Circulante/genética , Técnicas de Genotipagem/métodos , Sequenciamento de Nucleotídeos em Larga Escala , Neoplasias Pulmonares/genética , Adulto , Idoso , Idoso de 80 Anos ou mais , Antineoplásicos/farmacologia , Antineoplásicos/uso terapêutico , Biomarcadores Tumorais/antagonistas & inibidores , Carcinogênese/genética , Carcinoma Pulmonar de Células não Pequenas/sangue , Carcinoma Pulmonar de Células não Pequenas/diagnóstico , Carcinoma Pulmonar de Células não Pequenas/tratamento farmacológico , DNA Tumoral Circulante/sangue , DNA Tumoral Circulante/isolamento & purificação , Análise Mutacional de DNA , Resistencia a Medicamentos Antineoplásicos/genética , Feminino , Humanos , Biópsia Líquida , Pulmão/patologia , Neoplasias Pulmonares/sangue , Neoplasias Pulmonares/diagnóstico , Neoplasias Pulmonares/tratamento farmacológico , Masculino , Pessoa de Meia-Idade , Terapia de Alvo Molecular/métodos , Estudos Prospectivos , Sensibilidade e Especificidade , Adulto Jovem
6.
Am J Dermatopathol ; 36(10): 839-42, 2014 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-25247673

RESUMO

Primary cutaneous gamma-delta T-cell lymphoma (CGD-TCL) is a rare cutaneous T-cell lymphoma characterized by a rapidly progressive clinical course and a poor prognosis. We report a case of a 52-year-old man with a 10-year history of erythematous nodules and a rapid terminal progression diagnosed as CGD-TCL. Biopsies taken at the time of progression showed a dense lymphocytic infiltrate involving the subcutaneous adipose tissue and deep dermis. One of the biopsies displayed much more limited involvement by CGD-TCL that was nearly identical to the biopsies of the erythematous lesions 10 years before. In conclusion, this case demonstrates a case of CGD-TCL presenting as a longstanding indolent disease with a rapid terminal progression. The indolent clinical course and histological heterogeneity make diagnosing this entity during the initial stage extremely challenging. This case underscores a diverse clinical presentations and a need to consider CGD-TCL in patients showing subcutaneous lesions with an indolent clinical course.


Assuntos
Linfoma Cutâneo de Células T/patologia , Neoplasias Cutâneas/patologia , Progressão da Doença , Evolução Fatal , Humanos , Masculino , Pessoa de Meia-Idade , Receptores de Antígenos de Linfócitos T gama-delta
7.
Proc Natl Acad Sci U S A ; 93(24): 13774-9, 1996 Nov 26.
Artigo em Inglês | MEDLINE | ID: mdl-8943011

RESUMO

Spectral changes were measured with femtosecond resolution following low-intensity, broad-band excitation of the peripheral antenna complex of the purple photosynthetic bacterium Rhodobacter sphaeroides. Absorption anisotropy decays also were measured. We identified a 35-fs relaxation of the absorption and emission spectra of the excited state, as well as a 20-fs anisotropy decay. We interpret these results as interlevel relaxation and dephasing, respectively, of extensively delocalized exciton states of the circular bacteriochlorophyll aggregate.


Assuntos
Complexo de Proteínas do Centro de Reação Fotossintética/química , Rhodobacter sphaeroides/metabolismo , Cromatóforos Bacterianos/fisiologia , Genes Bacterianos , Lasers , Complexos de Proteínas Captadores de Luz , Complexo de Proteínas do Centro de Reação Fotossintética/biossíntese , Rhodobacter sphaeroides/genética , Deleção de Sequência , Espectrofotometria Infravermelho , Termodinâmica , Fatores de Tempo
8.
Biochemistry ; 33(26): 8089-100, 1994 Jul 05.
Artigo em Inglês | MEDLINE | ID: mdl-8025115

RESUMO

The temperature dependence of fluorescence on the picosecond to nanosecond time scale from the reaction centers of Rhodobacter sphaeroides strain R-26 and two mutants with elevated P/P+ midpoint potentials has been measured with picosecond time resolution. In all three samples, the kinetics of the fluorescence decay is complex and can only be well described with four or more exponential decay terms spanning the picosecond to nanosecond time range. Multiexponential fits are needed at all temperatures between 295 and 20 K. The complex decay kinetics are explained in terms of a dynamic solvation model in which the charge-separated state is stabilized after formation by protein conformational changes. Many of these motions have not had time to occur on the time scale of initial electron transfer and/or are frozen out at low temperature. This results in a time- and temperature-dependent enthalpy change between the excited singlet state and the charge-separated state that is the dominant term in the free energy difference between these states. Long-lived fluorescence is still observed even at 20 K, particularly for the high-potential mutants. This implies that the driving force for electron transfer on the nanosecond time scale at low temperature is less than 200 cm-1 (25 meV) in R-26 reaction centers and even smaller on the picosecond time scale or in the high-potential mutants.(ABSTRACT TRUNCATED AT 250 WORDS)


Assuntos
Complexo de Proteínas do Centro de Reação Fotossintética/metabolismo , Rhodobacter sphaeroides/metabolismo , Temperatura Baixa , Transporte de Elétrons , Cinética , Luz , Modelos Químicos , Mutação , Fótons , Complexo de Proteínas do Centro de Reação Fotossintética/química , Complexo de Proteínas do Centro de Reação Fotossintética/genética , Potenciometria , Rhodobacter sphaeroides/química , Rhodobacter sphaeroides/genética , Espectrometria de Fluorescência , Termodinâmica
9.
Biochemistry ; 33(26): 8101-12, 1994 Jul 05.
Artigo em Inglês | MEDLINE | ID: mdl-8025116

RESUMO

Detailed fast transient absorption measurements have been performed at low temperature on reaction centers from Rhodobacter sphaeroides strain R-26 and on a double mutant, [LH(L131) + LH-(M160)], in which the P/P+ oxidation potential is roughly 140 mV (1100 cm-1) above that of wild-type reaction centers. In both samples, the decay of the excited singlet state of the initial electron donor is not well described by a single-exponential decay term. This is particularly true for reaction centers from the double mutant where at least three exponential kinetic components are required to describe the decay, with time constants ranging from a few picoseconds to hundreds of picoseconds. However, singular value decomposition analysis of the time-dependent absorption change spectra indicates the presence of only two spectrally distinct states in reaction centers from both R-26 and the double mutant. Thus, the complex decay of P* at low temperature does not appear to be due to formation of either the state P+BA- as a distinct intermediate in electron transfer or P+BB- as an equilibrated side product of electron transfer. Instead, the decay kinetics are modeled by assuming dynamic solvation of the charge-separated state, as was done for the long-lived fluorescence decay in the accompanying paper [Peloquin, J. M., Williams, J. C., Lin, X., Alden, R. G., Taguchi, A. K. W., Allen, J.P., & Woodbury, N. W. (1994) Biochemistry 33, 8089-8100]. The results of assuming a static distribution of electron-transfer rates at early times followed by dynamic solvation of the charge-separated states on longer time scales are also presented. Regardless of which model is used to describe the early time kinetics of excited-state decay, the time-dependent excited-state population on the 100-ps or longer time scale is best described in terms of thermal repopulation of P* from the charge-separated state, even at 20 K. This results in a time- and temperature-dependent driving force estimated for initial electron transfer of less than 200 cm-1 on all time scales from picoseconds to nanoseconds. Assuming a nonzero internal reorganization energy associated with charge separation, the small driving force does not appear to be consistent with the lack of temperature dependence of electron transfer and the fact that a mutant with a P/P+ oxidation potential 140 mV (1100 cm-1) higher than wild type is still able to undergo electron transfer, even at low temperature.(ABSTRACT TRUNCATED AT 400 WORDS)


Assuntos
Complexo de Proteínas do Centro de Reação Fotossintética/metabolismo , Rhodobacter sphaeroides/metabolismo , Transporte de Elétrons , Luz , Modelos Químicos , Mutação , Complexo de Proteínas do Centro de Reação Fotossintética/química , Complexo de Proteínas do Centro de Reação Fotossintética/genética , Complexo de Proteínas do Centro de Reação Fotossintética/efeitos da radiação , Rhodobacter sphaeroides/química , Rhodobacter sphaeroides/genética , Espectrometria de Fluorescência , Espectrofotometria , Termodinâmica , Fatores de Tempo
11.
Biochemistry ; 32(13): 3498-505, 1993 Apr 06.
Artigo em Inglês | MEDLINE | ID: mdl-8461311

RESUMO

Two mutations, L168 His to Phe and L167 Phe to Leu, were made in residues near the primary electron donor, a bacteriochlorophyll dimer, of the reaction center from Rhodobacter sphaeroides. Blue shifts of 10-15 nm in the 865-nm band of the donor were observed in the optical absorption spectra of both of the mutant reaction centers. The rate of initial electron transfer was determined by measurement of the kinetics of the decay of the excited state of the donor, and the rate of charge recombination was determined by measurement of the recovery of the bleaching of the donor. The initial electron transfer time constant and the charge recombination time constant were determined to be 3.6 ps and 220 ms, respectively, in the L168 His to Phe mutant and 5.0 ps and 85 ms in the L167 Phe to Leu mutant, compared to 3.8 ps and 100 ms measured for the wild type. The oxidation potential of the donor measured by oxidation-reduction titrations was found to decrease by 80 mV in the L168 His to Phe mutant and increase by 25 mV in the L167 Phe to Leu mutant. Time-resolved fluorescence decay measurements indicated that the change in the oxidation potential of the donor in the L168 His to Phe mutant resulted in a change in the energies of the charge-separated states. The results show that an increase in the driving force does not increase the rate of the initial electron transfer reaction.(ABSTRACT TRUNCATED AT 250 WORDS)


Assuntos
Fotossíntese , Complexo de Proteínas do Centro de Reação Fotossintética/química , Rhodobacter sphaeroides/metabolismo , Histidina/química , Leucina/química , Complexos de Proteínas Captadores de Luz , Mutagênese Sítio-Dirigida , Oxirredução , Fenilalanina/química , Espectrometria de Fluorescência , Análise Espectral , Relação Estrutura-Atividade
12.
Biochemistry ; 31(45): 11029-37, 1992 Nov 17.
Artigo em Inglês | MEDLINE | ID: mdl-1445841

RESUMO

Mutations were made in four residues near the bacteriochlorophyll cofactors of the photosynthetic reaction center from Rhodobacter sphaeroides. These mutations, L131 Leu to His and M160 Leu to His, near the dimer bacteriochlorophylls, and M203 Gly to Asp and L177 Ile to Asp, near the monomer bacteriochlorophylls, were designed to result in the placement of a hydrogen bond donor group near the ring V keto carbonyl of each bacteriochlorophyll. Perturbations of the electronic structures of the bacteriochlorophylls in the mutants are indicated by additional resolved transitions in the bacteriochlorophyll absorption bands in steady-state low-temperature and time-resolved room temperature spectra in three of the resulting mutant reaction centers. The major effect of the two mutations near the dimer was an increase up to 80 mV in the donor oxidation-reduction midpoint potential. Correspondingly, the calculated free energy difference between the excited state of the primary donor and the initial charge separated state decreased by up to 55 mV, the initial forward electron-transfer rate was up to 4 times slower, and the rate of charge recombination between the primary quinone and the donor was approximately 30% faster in these two mutants compared to the wild type. The two mutations near the monomer bacteriochlorophylls had minor changes of 25 mV or less in the donor oxidation-reduction potential, but the mutation close to the monomer bacteriochlorophyll on the active branch resulted in a roughly 3-fold decrease in the rate of the initial electron transfer.


Assuntos
Bacterioclorofilas/genética , Complexo de Proteínas do Centro de Reação Fotossintética/metabolismo , Rhodobacter sphaeroides/metabolismo , Bacterioclorofilas/química , Transporte de Elétrons , Ligação de Hidrogênio , Complexos de Proteínas Captadores de Luz , Mutação , Oxirredução , Rhodobacter sphaeroides/genética , Espectrometria de Fluorescência , Análise Espectral
13.
Biochemistry ; 31(42): 10345-55, 1992 Oct 27.
Artigo em Inglês | MEDLINE | ID: mdl-1420154

RESUMO

A 51 bp section of the Rhodobacter capsulatus photosynthetic reaction center M subunit gene (nucleotides M562-M612 of the pufM structural sequence) encoding amino acids M187-M203 was replaced by the homologous region of the L subunit gene. This resulted in the symmetrization of much of the amino acid environment of the reaction center initial electron donor, P. This is the first in a series of large-scale symmetry mutations and is referred to as sym1. The sym1 mutant was able to grow photosynthetically, indicating that reaction center function was largely intact. Isolated reaction centers showed an approximately 10-nm blue shift in the QY band of P. The standard free energy change between P* and P+BphA- determined from analysis of the long-lived fluorescence from quinone-reduced reaction centers decreased from about -120 meV in the wild-type to about -75 meV in the sym1 mutant. A 65-70% quantum yield of electron transfer from P* to P+QA- was observed, most of the yield loss occurring between P* and P+BphA-. The decay of the stimulated emission from P* was about 3-fold slower in this mutant than in the wild-type. Time-resolved spectral analysis of the charge-separated intermediates formed in sym1 reaction centers indicated that the major product was P+BphA-. A model-dependent analysis of the observed rates and electron-transfer yields gave the following microscopic rate constants for sym1 reaction centers (wild-type values under the same conditions are given in parentheses): [formula: see text] Analysis of the sym1 mutant, mutants near P made by other groups, and interspecies variation of amino acids in the vicinity of P suggests that the protein asymmetry in the environment of the initial electron donor is important for optimizing the rate and yield of electron transfer, but is not strictly required for overall reaction center function.


Assuntos
Mutação , Complexo de Proteínas do Centro de Reação Fotossintética/genética , Complexo de Proteínas do Centro de Reação Fotossintética/metabolismo , Rhodobacter capsulatus/genética , Rhodobacter capsulatus/metabolismo , Sequência de Aminoácidos , Cromatóforos Bacterianos/metabolismo , Sequência de Bases , Clonagem Molecular , Transporte de Elétrons , Genes Bacterianos , Cinética , Substâncias Macromoleculares , Modelos Moleculares , Dados de Sequência Molecular , Complexo de Proteínas do Centro de Reação Fotossintética/isolamento & purificação , Plasmídeos , Conformação Proteica , Teoria Quântica , Homologia de Sequência de Aminoácidos , Espectrofotometria
14.
J Biol Chem ; 264(4): 1933-40, 1989 Feb 05.
Artigo em Inglês | MEDLINE | ID: mdl-2914887

RESUMO

The effects of high pressure (0.1-3.4 gigapascal (GPa)) on the ferrous heme active sites of human adult hemoglobin, sperm whale myoglobin, and Glycera dibranchiata hemoglobin (Fraction II) were probed using resonance Raman and absorption spectroscopies. High-to-low spin transitions of the heme iron occur for hemoglobin, myoglobin, and Glycera hemoglobin at 0.35, 0.75, and 0.50 GPa, respectively, for the deoxy species. These interspecies differences result from variations in the composition of the hemepockets and/or their rigidity to pressure-induced volume changes. Heme active sites initially bound to CO or O2 exhibit distinctive behavior at high pressures. For all proteins studied, O2 apparently dissociates from the heme at only moderately high pressure, while CO remains bound to the heme moiety even at extreme pressures. The Raman spectra demonstrate the differences in the ligated and deoxy species at 3.4 GPa in the high frequency region. Discrete changes (i.e. iron spin-state transitions and dissociation of O2) occur that are commensurate with the collapse of the distal pocket, while continuous shifts in the absorption and Raman spectra are observed at pressures above those required for pocket collapse.


Assuntos
Hemoglobina A/metabolismo , Hemoglobinas/metabolismo , Mioglobina/análogos & derivados , Mioglobina/metabolismo , Animais , Humanos , Matemática , Modelos Teóricos , Pressão , Espectrofotometria , Análise Espectral Raman , Baleias
16.
J Biol Chem ; 261(4): 1720-3, 1986 Feb 05.
Artigo em Inglês | MEDLINE | ID: mdl-3944105

RESUMO

Heme-linked ionizations of the acidic and basic isoenzymes of ferrous horseradish peroxidase influence both the Fe-histidine stretching mode and the oxidation-state marker line. First, Raman difference spectroscopy of horseradish peroxidase confirms earlier work showing that v(Fe-His) undergoes a transition in frequency with a pK that is characteristic of the enzyme's functional properties. The Fe-histidine mode shifts by about 2.5-3.0 cm-1 for horseradish peroxidase C and by about 6 cm-1 for the acidic isoenzyme. Further, we find that the oxidation-state marker line v4 also exhibits a transition with the same pK. For horseradish peroxidase C the shift in v4 is 0.4 cm-1 and the pK is 7.1 +/- .5, in good agreement with the pK found by other techniques. Shifts in these two Raman lines are correlated for the pK 7.1 transition and attain their highest frequency at low pH. The correlation is in marked contrast with R/T shifts in hemoglobins for which delta v(Fe-His) and delta v4 are also linearly related but shift in opposite directions. The shift in v4 suggests a mechanism for pH control of catalytic function based on ring pi-charge density effects on the energy of charge-depleted high oxidation-state intermediates. A second transition in v4 (delta v4 = 2.6 cm-1) with a pK of 10.0 is interpreted in terms of a change in ligation and spin state.


Assuntos
Peroxidase do Rábano Silvestre/metabolismo , Isoenzimas/metabolismo , Peroxidases/metabolismo , Heme/metabolismo , Histidina/metabolismo , Concentração de Íons de Hidrogênio , Ferro/metabolismo , Oxirredução , Conformação Proteica , Análise Espectral Raman
17.
J Biol Chem ; 260(22): 12194-7, 1985 Oct 05.
Artigo em Inglês | MEDLINE | ID: mdl-2995364

RESUMO

Time-resolved resonance Raman spectroscopy is a valuable tool for the study of the dynamics of heme-protein interactions. In particular, the photolysis of a ligand by short laser pulses allows for the examination of the dynamic evolution of heme-protein interactions subsequent to ligand dissociation. To date, such studies have been confined largely to hemoglobins and myoglobins. Here we present the results of the first transient Raman study of a peroxidase. Resonance Raman spectra of horseradish peroxidase were obtained within 10 ns of ligand (CO) photolysis at a variety of pH values. We find that there is only minimal relaxation of the heme pocket of horseradish peroxidase in response to ligand photolysis. This relaxation is pH-dependent and most probably involves the heme vinyl substituents. Such behavior is in sharp contrast to the transient behavior of most hemoglobins and beef heart cytochrome oxidase.


Assuntos
Monóxido de Carbono/metabolismo , Heme/metabolismo , Peroxidase do Rábano Silvestre/metabolismo , Peroxidases/metabolismo , Animais , Sítios de Ligação , Bovinos , Complexo IV da Cadeia de Transporte de Elétrons/metabolismo , Hemoglobinas/metabolismo , Cinética , Miocárdio/enzimologia , Mioglobina/metabolismo , Ligação Proteica , Conformação Proteica , Análise Espectral Raman/métodos , Relação Estrutura-Atividade
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