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1.
The bc
1 complex of the mitochondrial respiratory chain is essential for Plasmodium falciparum proliferation, the causative agent of human malaria. Therefore, this enzyme is an attractive target for antimalarials. However, biochemical investigations of the parasite enzyme needed for the study of new drugs are challenging. In order to facilitate the study of new compounds targeting the enzyme, we are modifying the inhibitor binding sites of the yeast Saccharomyces cerevisiae to generate a complex that mimics the P. falciparum enzyme. In this study we focused on its Qo pocket, the site of atovaquone binding which is a leading antimalarial drug used in treatment and causal prophylaxis. We constructed and studied a series of mutants with modified Qo sites where yeast residues have been replaced by P. falciparum equivalents, or, for comparison, by human equivalents. Mitochondria were prepared from the yeast Plasmodium-like and human-like Qo mutants. We measured the bc
1 complex sensitivity to atovaquone, azoxystrobin, a Qo site targeting fungicide active against P. falciparum and RCQ06, a quinolone-derivative inhibitor of P. falciparum bc
1 complex.The data obtained highlighted variations in the Qo site that could explain the differences in inhibitor sensitivity between yeast, plasmodial and human enzymes. We showed that the yeast Plasmodium-like Qo mutants could be useful and easy-to-use tools for the study of that class of antimalarials. 相似文献
2.
George Minasov Sivaraman Padavattan Ludmilla Shuvalova Joseph S. Brunzelle Darcie J. Miller Arnaud Basl�� Claudia Massa Frank R. Collart Tilman Schirmer Wayne F. Anderson 《The Journal of biological chemistry》2009,284(19):13174-13184
Cyclic di-GMP (c-di-GMP) is a ubiquitous bacterial second messenger that is
involved in the regulation of cell surface-associated traits and the
persistence of infections. Omnipresent GGDEF and EAL domains, which occur in
various combinations with regulatory domains, catalyze c-di-GMP synthesis and
degradation, respectively. The crystal structure of full-length YkuI from
Bacillus subtilis, composed of an EAL domain and a C-terminal
PAS-like domain, has been determined in its native form and in complex with
c-di-GMP and Ca2+. The EAL domain exhibits a triose-phosphate
isomerase-barrel fold with one antiparallel β-strand. The complex with
c-di-GMP-Ca2+ defines the active site of the putative
phosphodiesterase located at the C-terminal end of the β-barrel. The EAL
motif is part of the active site with Glu-33 of the motif being involved in
cation coordination. The structure of the complex allows the proposal of a
phosphodiesterase mechanism, in which the divalent cation and the general base
Glu-209 activate a catalytic water molecule for nucleophilic in-line attack on
the phosphorus. The C-terminal domain closely resembles the PAS-fold. Its
pocket-like structure could accommodate a yet unknown ligand. YkuI forms a
tight dimer via EAL-EAL and trans EAL-PAS-like domain association.
The possible regulatory significance of the EAL-EAL interface and a mechanism
for signal transduction between sensory and catalytic domains of
c-di-GMP-specific phosphodiesterases are discussed.The dinucleotide cyclic di-GMP (c-di-GMP) was discovered about 20 years ago
when it was found to regulate the activity of cellulase synthase in
Acetobacter xylinum
(1). However, its prominent
role as a global second messenger has been realized only upon the recent
recognition of the omnipresence of genes coding for domains that catalyze
c-di-GMP biosynthesis and degradation in eubacteria
(2). GGDEF domains catalyze the
condensation of two GTP molecules to the cyclic 2-fold symmetric dinucleotide
(diguanylate cyclase activity
(3-6)),
whereas EAL domains are involved in its degradation to yield the linear
dinucleotide pGpG (phosphodiesterase
(PDE)4 A activity)
(3,
7-9).
Recently, also HD-GYP domains have been implicated in c-di-GMP-specific PDE
activity (10). All the domains
have been named according to their sequence signature motifs. They are
typically found in combinations with various other, mostly sensory or
regulatory, domains. It is thought that the balance between antagonistic
diguanylate cyclase and PDE-A activities determines the cellular level of
c-di-GMP and, thus, affects a variety of physiological processes in
bacteria.It has been shown that, in general, c-di-GMP regulates cell
surface-associated traits and community behavior such as biofilm formation
(for reviews see Refs.
11-12),
and its relevance to the virulence of pathogenic bacteria has been
demonstrated (11,
13,
14). In particular, the
dinucleotide has been proposed to orchestrate the switch between acute and
persistent phase of infection.The best characterized diguanylate cyclase is PleD from Caulobacter
crescentus with a Rec-Rec-GGDEF domain architecture (Rec indicates
response regulator receiver domain). The structure of its GGDEF domain
revealed a single GTP-binding site and suggested that dimerization is the
prerequisite for enzymatic activity
(4). This has been corroborated
recently by crystallography showing directly that
modification of the first Rec
domain, mimicking phosphorylation by the cognate kinase, induces formation of
a tightly packed dimer (15).
Additionally, an upper limit of c-di-GMP levels in the cell seems to be
ensured by potent allosteric product inhibition of the PleD cyclase
(4,
15,
16). Recently, the crystal
structure of another diguanylate cyclase, WspR from Pseudomonas
aeruginosa with a Rec-GGDEF domain architecture, has been determined
(17), which showed a
tetrameric quaternary structure and active and feedback inhibition sites that
are very similar to those in PleD.For EAL domains, it has been demonstrated that genetic knock-out results in
phenotypes that are in line with the paradigm that an elevated cellular
c-di-GMP concentration corresponds to a sessile and a low concentration to a
motile bacterial life style
(13,
18,
19). Only recently,
EAL-mediated PDE-A activity has been measured in vitro
(7-9,
20-22).The Bacillus subtilis YkuI protein was targeted for structure
determination by the Midwest Center for Structural Genomics as a member of the
large sequence family that contains EAL (Pfam number PF00563) domains. Here we
report the crystal structure of YkuI showing the fold of the N-terminal EAL
domain and the C-terminal PAS-like domain. Co-crystallization with c-di-GMP
revealed the substrate binding mode and allows the proposal of a catalytic
mechanism. The PAS-like domain most probably has regulatory function, which is
discussed. Recently, another EAL structure has been deposited in the Protein
Data Bank by the Midwest Center for Structural Genomics, the EAL domain of a
GGDEF-EAL protein from Thiobacillus denitrificans (tdEAL; PDB code
2r6o). Comparison of the two structures suggests a possible regulatory
mechanism. 相似文献
3.
Reaction Mechanism of Superoxide Generation during Ubiquinol Oxidation by the Cytochrome bc1 Complex
Ying Yin Shaoqing Yang Linda Yu Chang-An Yu 《The Journal of biological chemistry》2010,285(22):17038-17045
In addition to its main functions of electron transfer and proton translocation, the cytochrome bc1 complex (bc1) also catalyzes superoxide anion (O2˙̄) generation upon oxidation of ubiquinol in the presence of molecular oxygen. The reaction mechanism of superoxide generation by bc1 remains elusive. The maximum O2˙̄ generation activity is observed when the complex is inhibited by antimycin A or inactivated by heat treatment or proteinase K digestion. The fact that the cytochrome bc1 complex with less structural integrity has higher O2˙̄-generating activity encouraged us to speculate that O2˙̄ is generated inside the complex, perhaps in the hydrophobic environment of the QP pocket through bifurcated oxidation of ubiquinol by transferring its two electrons to a high potential electron acceptor, iron-sulfur cluster, and a low potential heme bL or molecular oxygen. If this speculation is correct, then one should see more O2˙̄ generation upon oxidation of ubiquinol by a high potential oxidant, such as cytochrome c or ferricyanide, in the presence of phospholipid vesicles or detergent micelles than in the hydrophilic conditions, and this is indeed the case. The protein subunits, at least those surrounding the QP pocket, may play a role either in preventing the release of O2˙̄ from its production site to aqueous environments or in preventing O2 from getting access to the hydrophobic QP pocket and might not directly participate in superoxide production. 相似文献
4.
5.
Li Min Zhongmin Jin Ljubica Caldovic Hiroki Morizono Norma M. Allewell Mendel Tuchman Dashuang Shi 《The Journal of biological chemistry》2009,284(8):4873-4880
N-Acetylglutamate synthase (NAGS) catalyzes the first committed step in
l-arginine biosynthesis in plants and micro-organisms and is subject to feedback
inhibition by l-arginine. This study compares the crystal structures of NAGS from
Neisseria gonorrhoeae (ngNAGS) in the inactive T-state with
l-arginine bound and in the active R-state complexed with CoA and
l-glutamate. Under all of the conditions examined, the enzyme consists of two stacked
trimers. Each monomer has two domains: an amino acid kinase (AAK) domain with an AAK-like fold
but lacking kinase activity and an N-acetyltransferase (NAT) domain
homologous to other GCN5-related transferases. Binding of l-arginine to the AAK
domain induces a global conformational change that increases the diameter of the hexamer by
∼10 Å and decreases its height by
∼20Å. AAK dimers move 5Å outward along their
2-fold axes, and their tilt relative to the plane of the hexamer decreases by
∼4°. The NAT domains rotate ∼109° relative to
AAK domains enabling new interdomain interactions. Interactions between AAK and NAT domains on
different subunits also change. Local motions of several loops at the
l-arginine-binding site enable the protein to close around the bound ligand, whereas
several loops at the NAT active site become disordered, markedly reducing enzymatic specific
activity.l-Arginine biosynthesis in most micro-organisms and plants involves the initial
acetylation of l-glutamate by N-acetylglutamate synthase (NAGS, EC
2.3.1.1)2 to produce N-acetylglutamate
(NAG). NAG is then converted by NAG kinase (NAGK, EC 2.7.2.8) to NAG-phosphate and subsequently
to N-acetylornithine (1, 2). Two alternative reactions are used to remove the acetyl
group from acetylornithine. The linear pathway uses N-acetylornithine
deacetylase (EC 3.5.1.16) to catalyze the metal-dependent hydrolysis of the acetyl group to form
l-ornithine and acetate, whereas the acetyl recycling pathway transfers the acetyl
group from N-acetylornithine to l-glutamate, producing
l-ornithine and NAG. This reaction is catalyzed by ornithine acetyltransferase (EC
2.3.1.35).In the linear pathway, NAGS is the only target of feedback inhibition by l-arginine.
In contrast, in the acetyl cycling pathway l-arginine may inhibit NAGS and NAGK or
ornithine acetyltransferase (3). Structure
determinations of l-arginine-insensitive (4)
and l-arginine-sensitive NAGKs (5) provided
insights into the structural basis of l-arginine inhibition of NAGK.
l-Arginine-insensitive Escherichia coli (ec) NAGK is
a homodimer (4), whereas l-arginine-sensitive
NAGKs from Thermotoga maritima (tm) and Pseudomonas
aeruginosa (pa) are hexamers formed by pair-wise interlacing of the
N-terminal helices of three ecNAGK-like dimers, to create a second type of
dimer interface. l-Arginine binding to a site close to the C terminus induces global
conformational changes that expands the ring by ∼8 Å and decreases the
tilt of the ecNAGK-like dimers relative to the plane of the ring by
∼6°. The inhibition mechanism was proposed to involve the
enlargement of an active site located close to the l-arginine-binding site.Because of the sequence similarity between NAGK and NAGS, it was speculated that they may have
similar l-arginine-binding sites and hexameric ring structures (5). However, our recent structural determination of NAGS from
Neisseria gonorrhoeae (ng) revealed the active site to be
located in the NAT domain, >25 Å away from the proposed
l-arginine-binding site (6). Therefore, the
allosteric mechanism of NAGS is likely to be different from that of
l-arginine-sensitive NAGKs. Here we compare the structures of ngNAGS
in the inactive T-state with l-arginine bound and in the R-state complexed with CoA and
l-glutamate and determine the structural basis for the allosteric inhibition of NAGS
by l-arginine. 相似文献
6.
Abstract: The catecholaminergic neurotoxin 6-hydroxydopamine causes parkinsonian symptoms in animals and it has been proposed that reactive oxygen species and oxidative stress, enhanced by iron, may play a key role in its toxicity. The present results demonstrate that 6-hydroxydopamine reversibly inhibits complex I (NADH dehydrogenase) of brain mitochondrial respiratory chain in isolated mitochondria. 6-Hydroxydopamine itself, rather than its oxidative products, was responsible for the inhibition. Iron(III) did not enhance inhibition but decreased it by stimulating the nonenzyme oxidation of 6-hydroxydopamine. Inhibition was potentiated to some extent by calcium ion. Desferrioxamine protected complex I activity against the inhibition, but it was not due to its chelator or antioxidative properties. Desferrioxamine was also shown to activate NADH dehydrogenase in the absence of 6-hydroxydopamine. Activation of mitochondrial respiration by desferrioxamine may contribute to the enhanced neuron survival in the presence of desferrioxamine in some neurodegenerative conditions. 相似文献
7.
8.
Isaura Torres Orville Hernandez Diana Tamayo Jose F. Mu?oz Natanael P. Leit?o Jr Ana M. García Angela Restrepo Rosana Puccia Juan G. McEwen 《PloS one》2013,8(7)
Glycoprotein gp43 is an immunodominant diagnostic antigen for paracoccidioidomycosis caused by Paracoccidioides brasiliensis. It is abundantly secreted in isolates such as Pb339. It is structurally related to beta-1,3-exoglucanases, however inactive. Its function in fungal biology is unknown, but it elicits humoral, innate and protective cellular immune responses; it binds to extracellular matrix-associated proteins. In this study we applied an antisense RNA (aRNA) technology and Agrobacterium tumefaciens-mediated transformation to generate mitotically stable PbGP43 mutants (PbGP43 aRNA) derived from wild type Pb339 to study its role in P. brasiliensis biology and during infection. Control PbEV was transformed with empty vector. Growth curve, cell vitality and morphology of PbGP43 aRNA mutants were indistinguishable from those of controls. PbGP43 expression was reduced 80–85% in mutants 1 and 2, as determined by real time PCR, correlating with a massive decrease in gp43 expression. This was shown by immunoblotting of culture supernatants revealed with anti-gp43 mouse monoclonal and rabbit polyclonal antibodies, and also by affinity-ligand assays of extracellular molecules with laminin and fibronectin. In vitro, there was significantly increased TNF-α production and reduced yeast recovery when PbGP43 aRNA1 was exposed to IFN-γ-stimulated macrophages, suggesting reduced binding/uptake and/or increased killing. In vivo, fungal burden in lungs of BALB/c mice infected with silenced mutant was negligible and associated with decreased lung ΙΛ−10 and IL-6. Therefore, our results correlated low gp43 expression with lower pathogenicity in mice, but that will be definitely proven when PbGP43 knockouts become available. This is the first study of gp43 using genetically modified P. brasiliensis. 相似文献
9.
10.
11.
Pyrimorph is a novel fungicide with high activity against the plant pathogen Phytophthora capsici. We investigated the risk that P. capsici can develop resistance to pyrimorph. The baseline sensitivities of 226 P. capsici isolates, tested by mycelial growth inhibition, showed a unimodal distribution with a mean EC50 value of 1.4261 (±0.4002) µg/ml. Twelve pyrimorph-resistant mutants were obtained by repeated exposure to pyrimorph in vitro with a frequency of approximately 1×10−4. The resistance factors of the mutants ranged from 10.67 to 56.02. Pyrimorph resistance of the mutants was stable after 10 transfers on pyrimorph-free medium. Fitness in sporulation, cystospore germination, and pathogenicity in the pyrimorph-resistant mutants was similar to or less than that in the parental wild-type isolates. On detached pepper leaves and pepper plants treated with the recommended maximum dose of pyrimorph, however, virulence was greater for mutants with a high level of pyrimorph resistance than for the wild type. The results suggest that the risk of P. capsici developing resistance to pyrimorph is low to moderate. Among mutants with a high level of pyrimorph resistance, EC50 values for pyrimorph and CAA fungicides flumorph, dimethomorph, and mandipropamid were positively correlated. This indicated that point mutations in cellulose synthase 3 (CesA3) may confer resistance to pyrimorph. Comparison of CesA3 in isolates with a high level of pyrimorph resistance and parental isolates showed that an amino acid change from glutamine to lysine at position 1077 resulted in stable, high resistance in the mutants. Based on the point mutations, an allele-specific PCR method was developed to detect pyrimorph resistance in P. capsici populations. 相似文献
12.
Uma D. Vempati Xianlin Han Carlos T. Moraes 《The Journal of biological chemistry》2009,284(7):4383-4391
Cytochrome c (cyt c) is a heme-containing protein that
participates in electron transport in the respiratory chain and as a signaling
molecule in the apoptotic cascade. Here we addressed the effect of removing
mammalian cyt c on the integrity of the respiratory complexes in
mammalian cells. Mitochondria from cyt c knockout mouse cells lacked
fully assembled complexes I and IV and had reduced levels of complex III. A
redox-deficient mutant of cyt c was unable to rescue the levels of
complexes I and IV. We found that cyt c is associated with both
complex IV and respiratory supercomplexes, providing a potential mechanism for
the requirement for cyt c in the assembly/stability of complex
IV.The mitochondrial electron transport chain consists of four multisubunit
complexes, namely, NADH-ubiquinone oxidoreductase (complex
I),2
succinate-ubiquinone oxidoreductase (complex II), ubiquinone-cytochrome
c oxidoreductase (complex III), and cytochrome c oxidase
(complex IV, COX). Cytochrome c (cyt c) shuttles electrons
from oxidative phosphorylation complex III to complex IV. Electrons are
transferred from reduced cyt c sequentially to the CuA
site, heme a, heme a3, and CuB
binuclear center in the complex IV before being finally transferred to
molecular oxygen to generate water
(1). Respiratory complexes are
assembled into supercomplexes (also called respirasomes). These contain
complex I bound to dimeric complex III and a variable copy number of complex
IV (2).In Saccharomyces cerevisiae, cyt c is encoded by two
genes: CYC1 and CYC7. Mutagenesis studies in yeast have
shown that cyt c is required for the assembly of COX
(3,
4). In yeast lacking both the
cyt c genes (CYC1 and CYC7), COX assembly was
absent. It was also shown that cyt c is only structurally required
for COX assembly, because a catalytic mutant of cyt c (W65S) was
sufficient to bring about near normal levels of COX. However, because yeast
lacks complex I, they could not analyze the role of cyt c in the
assembly/stability of complex I. Mammals possess two different isoforms of cyt
c encoded on different chromosomes: the somatic (cyt cS)-
and testis (cyt cT)-specific isoforms. In mouse, the cDNAs bear 74%
homology, whereas the proteins possess 86% identity with most dissimilarity in
the C terminus.Cardiolipin (CL) is an anionic phospholipid present almost exclusively in
the mitochondrial membranes and constitutes 25% of its total phospholipids
(5). Work from several
laboratories showed that CL is essential for the membrane anchorage of the
respiratory supercomplexes. CL has two main roles in the mitochondrial
structure and function, namely, stabilization of mitochondrial membranes and
specific interactions with proteins. CL deficiency results in inefficient
energy transformation by oxidative phosphorylation, swelling of mitochondria,
decreased ATP/oxygen ratio, and reduced membrane potential
(6,
7). In accordance, in S.
cerevisiae lacking CL synthase, the supercomplex comprising complexes III
and IV is unstable (8).
Assembly mutants of COX had significantly reduced CL synthase activity,
whereas assembly mutants of respiratory complex III and complex V showed less
inhibition (9). Subsequently,
the proton gradient across the inner mitochondrial membrane was found to be
important for CL formation and that CL synthase was stimulated by alkaline pH
at the matrix side (10). In
this study, we investigated the role of cyt c depletion on CL levels
by examining its content and composition in cyt c null cells.Here we aimed to answer the following questions: What is the role of cyt
c in the assembly and maintenance of the different respiratory
complexes in mammals? Are there changes in the content/composition of lipids
in the cyt c-ablated cells? Analysis of mouse fibroblasts revealed
that cyt c is essential for the assembly/stability of COX, and a
catalytically mutant form of cyt c cannot rescue the COX defect in
the cyt c null cells. CL and triacylglycerols showed significant
differences in the cyt c null cells, both in content and
composition. 相似文献
13.
Pauline Gaignard Minal Menezes Manuel Schiff Aurélien Bayot Malgorzata Rak Hélène Ogier?de?Baulny Chen-Hsien Su Mylene Gilleron Anne Lombes Heni Abida Alexander Tzagoloff Lisa Riley Sandra?T. Cooper Kym Mina Padma Sivadorai Mark?R. Davis Richard?J.N. Allcock Nina Kresoje Nigel?G. Laing David?R. Thorburn Abdelhamid Slama John Christodoulou Pierre Rustin 《American journal of human genetics》2013,93(2):384-389
Many individuals with abnormalities of mitochondrial respiratory chain complex III remain genetically undefined. Here, we report mutations (c.288G>T [p.Trp96Cys] and c.643C>T [p.Leu215Phe]) in CYC1, encoding the cytochrome c1 subunit of complex III, in two unrelated children presenting with recurrent episodes of ketoacidosis and insulin-responsive hyperglycemia. Cytochrome c1, the heme-containing component of complex III, mediates the transfer of electrons from the Rieske iron-sulfur protein to cytochrome c. Cytochrome c1 is present at reduced levels in the skeletal muscle and skin fibroblasts of affected individuals. Moreover, studies on yeast mutants and affected individuals’ fibroblasts have shown that exogenous expression of wild-type CYC1 rescues complex III activity, demonstrating the deleterious effect of each mutation on cytochrome c1 stability and complex III activity. 相似文献
14.
There are now four structures of vertebrate mitochondrial bc
1 complexes available in theprotein databases and structures from yeast and bacterial sources are expected soon. Thisreview summarizes the new information with emphasis on the avian cytochrome bc
1 complex(PDB entries 1BCC and 3BCC). The Rieske iron–sulfur protein is mobile and this has beenproposed to be important for catalysis. The binding sites for quinone have been located basedon structures containing inhibitors and, in the case of the quinone reduction site Qi, thequinone itself. 相似文献
15.
16.
17.
Wen-hua Liu Jing-jin Liu Jian Wu Lu-lu Zhang Fang Liu Li Yin Mao-mao Zhang Bo Yu 《PloS one》2013,8(1)
Mesenchymal stem cells (MSCs) can suppress dendritic cells (DCs) maturation and function, mediated by soluble factors, such as indoleamine 2,3-dioxygenase (IDO), prostaglandin E2 (PGE2), and nitric oxide (NO). Interleukin-10 (IL-10) is a common immunosuppressive cytokine, and the downstream signaling of the JAK-STAT pathway has been shown to be involved with DCs differentiation and maturation in the context of cancer. Whether IL-10 and/or the JAK-STAT pathway play a role in the inhibitory effect of MSCs on DCs maturation remains controversial. In our study, we cultured MSCs and DCs derived from rat bone marrow under different culturing conditions. Using Transwell plates, we detected by ELISA that the level of IL-10 significantly increased in the supernatants of MSC-DC co-cultures at 48 hours. The cell immunofluorescence assay suggested that the MSCs secreted more IL-10 than the DCs in the co-cultures. Adding exogenous IL-10 to the DCs monoculture or MSC-DC co-cultures stimulated IL-10 and led to a decrease in IL-12, and lower expression of the DCs surface markers CD80, CD86, OX62, MHC-II and CD11b/c. Supplementing the culture with an IL-10 neutralizing antibody (IL-10NA) showed precisely the opposite effect of adding IL-10. Moreover, we demonstrated that the JAK-STAT signaling pathway is involved in inhibiting DCs maturation. Both JAK1 and STAT3 expression and IL-10 secretion decreased markedly after adding a JAK inhibitor (AG490) to the co-culture plate. We propose that there is an IL-10 positive feedback loop, which may explain our observations of elevated IL-10 and enhanced JAK1 and STAT3 expression. Overall, we demonstrated that MSCs inhibit the maturation of DCs through the stimulation of IL-10 secretion, and by activating the JAK1 and STAT3 signaling pathway. 相似文献
18.
Célia M. Silveira Pedro O. Quintas Isabel Moura José J. G. Moura Peter Hildebrandt M. Gabriela Almeida Smilja Todorovic 《PloS one》2015,10(6)
Cytochrome cd1 nitrite reductases (cd
1NiRs) catalyze the one-electron reduction of nitrite to nitric oxide. Due to their catalytic reaction, cd
1NiRs are regarded as promising components for biosensing, bioremediation and biotechnological applications. Motivated by earlier findings that catalytic activity of cd
1NiR from Marinobacter hydrocarbonoclasticus (Mhcd
1) depends on the presence of its physiological redox partner, cytochrome c
552 (cyt c
552), we show here a detailed surface enhanced resonance Raman characterization of Mhcd
1 and cyt c
552 attached to biocompatible electrodes in conditions which allow direct electron transfer between the conducting support and immobilized proteins. Mhcd
1 and cyt c552 are co-immobilized on silver electrodes coated with self-assembled monolayers (SAMs) and the electrocatalytic activity of Ag // SAM // Mhcd
1 // cyt c
552 and Ag // SAM // cyt c
552 // Mhcd
1 constructs is tested in the presence of nitrite. Simultaneous evaluation of structural and thermodynamic properties of the immobilized proteins reveals that cyt c
552 retains its native properties, while the redox potential of apparently intact Mhcd
1 undergoes a ~150 mV negative shift upon adsorption. Neither of the immobilization strategies results in an active Mhcd
1, reinforcing the idea that subtle and very specific interactions between Mhcd
1 and cyt c
552 govern efficient intermolecular electron transfer and catalytic activity of Mhcd
1. 相似文献
19.
20.