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1.
Vojtech Ličko 《Bulletin of mathematical biology》1967,29(1):1-16
A vast number of biologically important processes are based upon bimolecular systems. In these systems intermediate complexes
are formed. Bimolecular systems in which no complex-complex interactions occur are called linear systems of complexes. A definition
and some characteristic properties of these systems are given here. There may exist a contradiction of Onsager's principle
of detailed balancing in these systems; however, no principal differences are found between the steady state behavior of an
open system and that of a closed system. It is shown that the steady state behavior of a linear system of complexes of arbitrary
complexity has some similarities with the steady state behavior of a simple bimolecular system, e.g., Michaelis-Menten enzymatic
reaction. Multiplicity of action of the substances participating in biomolecular processes may produce some qualitative differences
in the steady state behavior of the system. 相似文献
2.
Narimasa Saito 《Bioscience, biotechnology, and biochemistry》2013,77(7):621-625
When the ‘dihydroxyacetone-fermentation’ was carried out in a steady state by the cells of Br. fuscum, it was suggested that the consumption rate of glucose in the medium might be regulated at the initial stages of glucose degradation such as; (a) glucose isomerization, (b) glucose dehydrogenation, and (c) glucose phosphorylation. Of these three enzymatic reactions, the isomerization and the dehydrogenation were proved to be unable to occur or negligible in vivo. So, in consideration of the pool sizes of Mg+ +, Pi, H+, glucose, G6P*, ATP, ADP, etc., the intracellular glucokinase** activity was calculated. Results indicate that glucokinase reaction may be the limiting factor for direct glucose metabolism in Br. fuscum. 相似文献
3.
Di-2-pyridyl ketone isonicotinoyl hydrazone (HPKIH) and a range of its analogues comprise a series of monobasic acids that are capable of binding iron (Fe) as tridentate (N,N,O) ligands. Recently, we have shown that these chelators are highly cytotoxic, but show selective activity against cancer cells. Particularly interesting was the fact that cytotoxicity of the HPKIH analogues is maintained even after complexation with Fe. To understand the potent anti-tumor activity of these compounds, we have fully characterized their chemical properties. This included examination of the solution chemistry and X-ray crystal structures of both the ligands and Fe complexes from this class and the ability of these complexes to mediate redox reactions. Potentiometric titrations demonstrated that all chelators are present predominantly in their charge-neutral form at physiological pH (7.4), allowing access across biological membranes. Keto–enol tautomerism of the ligands was identified, with the tautomers exhibiting distinctly different protonation constants. Interestingly, the chelators form low-spin (diamagnetic) divalent Fe complexes in solution. The chelators form distorted octahedral complexes with FeII, with two tridentate ligands arranged in a meridional fashion. Electrochemistry of the Fe complexes in both aqueous and non-aqueous solutions revealed that the complexes are oxidized to their ferric form at relatively high potentials, but this oxidation is coupled to a rapid reaction with water to form a hydrated (carbinolamine) derivative, leading to irreversible electrochemistry. The Fe complexes of the HPKIH analogues caused marked DNA degradation in the presence of hydrogen peroxide. This observation confirms that Fe complexes from the HPKIH series mediate Fenton chemistry and do not repel DNA. Collectively, studies on the solution chemistry and structure of these HPKIH analogues indicate that they can bind cellular Fe and enhance its redox activity, resulting in oxidative damage to vital biomolecules.Electronic Supplementary Material Supplementary material is available in the online version of this article at .Abbreviations DFO
desferrioxamine
-
HPKIH
di-2-pyridyl ketone isonicotinoyl hydrazone
-
HNIH
2-hydroxy-1-naphthaldehyde isonicotinoyl hydrazone
-
HPCIH
2-pyridinecarbaldehyde isonicotinoyl hydrazone
-
HPIH
pyridoxal isonicotinoyl hydrazone
- L
linear DNA
- OC
open circular DNA
- SC
supercoiled DNA 相似文献
4.
Equations for the time-dependent concentrations of all species involved in the general mechanism of human plasminogen activation
proposed by Wohlet al. (J. biol. Chem.
255, 2005–2013, 1980) have been derived. These equations are valid for the whole course of the reaction: for both the transient
phase and the steady state. In addition, we compare our results with the ones obtained by the above-mentioned authors for
the steady state assuming rapid equilibrium conditions. Finally, we propose a method for the determination of all velocity
constants. 相似文献
5.
Ennio Lazzarini 《Rendiconti Lincei》2003,14(1):5-75
Positronium, Ps, the bound state between an electron, e, and a positron, c+, may have two spin states: theortho,o-Ps, and thepara,p-Ps, states, which differ for the spin orientation of the two particles. The two types of Ps atoms may be inter-converted
by collision with paramagnetic compounds, such as several3d complexes. By investigating about 90 complexes of VII, CrII, CrIII, MnII, FeII, CoII and NiII as a function of temperature, it was found that the rate constants kCR of theo-Ps intop-Ps conversion reactions, CR, are linearly correlated to the delocalization β of metal electrons caused by the ligands. Therefore,
if β known, kCR may be estimated andvice versa. This suggests a new method for the experimental determination of β. The rate constants of the Ps oxidation reactions by
CoIII complexes were also investigated and discussed. The paper is preceded by four sections dealing with: 1) the positron and
positronium formation; 2) the positron annihilation modes; 3) the methods for measuring the Ps rate constants and establishing
the Ps reaction types; 4) the application of the Smoluchowski equation to Ps reactions. Moreover, an attempt is made to ascertain
the standard electrochemical potential of Ps atoms. The positron reactions and the formation of positronides are also taken
into consideration.
Presentata nella seduta del 13 dicembre 2002 dal Socio F. Calderazzo. 相似文献
6.
H. Lundegårdh 《Physiologia plantarum》1968,21(1):148-167
- 1 Two separate light reactions may be distinguished: (I) the reduction of ferredoxin and NADP probably by oxidation of carotene to xanthophyll; (II) the oxida tion of cytochrome f by chlorophyll (probably a). Reaction II implies a return of electrons to the pigments, system III, thus maintaining its normal steady state of oxidation-reduction. The xanthophyll is hereby again reduced to carotene.
- 2 System I is sensitive to violet-blue-green and probably also infrared light. Carotene absorbs in these regions, ferredoxin in blue-violet. System II is primarily sensitive to red light but also to blue-violet. Both chlorophyll and cytochromes absorb in the latter region, the cytochromes also in green.
- 3 The response of systems I and II to different spectral regions was studied by means of a special spectrophotometric flash technique, enabling precise measure ments of the band-height of the enzymes involved. The initial photic reactions of systems I and II, viz., the reduction of ferredoxin-NADP and the oxidation of cyto chrome f show a full turnover in less than 0.1 ms but the transfer between systems I and II by means of which the cytochromes are reduced is slowed down to about 10?1-10?2 s. The initial effect may thus be observed during ca. 0.1 s. At continuous illumination the displacement of the steady states of the enzymes may last up to several seconds and then return to a state of only partial reduction. Erroneous inter pretations of these phenomena are corrected.
- 4 In the blue-sensitive system I ferredoxin alone mediates the reduction of NADP but the possibility of the presence of other factors capable of dark chemical elec tron transfer is discussed. In the red-sensitive system II three cytochromes operate, viz., f, b3 and b6. Spectrophotometric evidence for the existence of two cytochromes b is presented. Cytochromes b6 and f are approximately synchronously oxidized and reduced, whereas b3 reacts somewhat independently. Cytochrome b3 probably acts as a decharger of OH? and compensates for the capture of H++ e? at the reduction of triphosphopyridine nucleotide (NAD) or of electrons by other oxidants.
- 5 The transfer of electrons between systems I and II maintains a reversible steady state of oxidation-reduction that may be moved to one side or the other not only by monochromatic light but also in the dark under influence of N2, O2, the ratios NADP/NADPH and ADP/ATP, and various added substances. Spectrophotometric measurements in UV show that a flavoprotein participates in the multiple steady state.
- 6 The investigations illustrate many intricate technical problems that are too frequently overlooked. Photostructural reactions must be eliminated by referring band-heights to an isosbestic level. The photosynthetic activity is strongly dependent on light-scattering. Reliable measurements of cytochromes must be made in the α-region owing to a strong interference of rapid changes of the ratio carotene/xanthophyll in the region of the γ-bands.
7.
Mendieta-Wejebe JE Rosales-Hernández MC Rios H Trujillo-Ferrara J López-Pérez G Tamay-Cach F Ramos-Morales R Correa-Basurto J 《Journal of molecular modeling》2008,14(6):537-545
Cytochrome P-450 is a group of enzymes involved in the biotransformation of many substances, including drugs. These enzymes
possess a heme group (1) that when it is properly modified induces several important physicochemical changes that affect their enzymatic activity.
In this work, the five structurally modified heme derivatives 2–6 and the native heme 1 were docked on CYP2B4, (an isoform of P450), in order to determine whether such modifications alter their binding form and
binding affinity for CYP2B4 apoprotein. In addition, docking calculations were used to evaluate the affinity of CYP2B4 apoprotein-heme
complexes for aniline (A) and N-methyl-aniline (NMA). Results showing the CYP2B4 heme 4- and heme 6-apoprotein complexes to be most energetically stable indicate that either hindrance effects or electronic properties are
the most important factors with respect to the binding of heme derivatives at the heme-binding site. Furthermore, although
all heme-apoprotein complexes demonstrated high affinity for both A and NMA, the CYP2B4 apoprotein-5 complex had higher affinity for A, and the heme 6 complex had higher affinity for NMA. Finally, surface electronic properties (SEP) were calculated in order to explain why
certain arginine residues of CYP2B4 apoprotein interact with polarizable functionalities, such as ester groups or sp
2
carbons, present in some heme derivates. The main physicochemical parameter involved in the recognition process of the heme
derivatives, the CYP2B4 apoprotein and A or NMA, are reported.
Figure Scheme of steps to be followed for obtaining five new CYP2B4 apoprotein-heme complexes by docking 相似文献
8.
There is an emerging market for functional oligosaccharides for use in foods. Currently, technology for the production of
oligosaccharides is limited to extraction from plant sources, acid or enzymatic hydrolysis of polysaccharides or synthesis
by transglycosylation reactions. Oligosaccharides can also be produced using a Leuconostoc fermentation and restricting the polymer size by addition of maltose. Maltose limits the dextransucrase reaction, yielding
high concentrations of α-glucooligosaccharides. Branched oligomers produced by this process were readily catabolized by bifidobacteria
and lactobacilli but were not readily utilized by either Salmonella sp. or Escherichia coli, pointing toward their use in intestinal microflora modification. Journal of Industrial Microbiology & Biotechnology (2002) 29, 196–199 doi:10.1038/sj.jim.7000269
Received 13 February 2002/ Accepted in revised form 29 April 2002 相似文献
9.
S. M. Bailey A-L. Fauconnet 《Redox report : communications in free radical research》2013,18(1):17-22
SummaryHydroxylation of salicylate and D-phenylalanine was measured to test the usefulness of these compounds for hydroxyl radical (HO?) detection in chemical and biological systems. When HO? were produced by the photolytic decomposition of hydrogen peroxide, nearly equal amounts of 2,5- and 2,3-dihydroxybenzoic acid (DHBA) were produced from salicylate, with catechol as a minor product. In the photolytic reaction, nearly equal concentrations of p-,m-, and o-tyrosine were formed from D-phenylalanine. When salicylate or D-phenylalanine was present with Fenton reagents or in iron(II) autoxidation systems, the relative proportions of hydroxylated products were similar to those observed after photolysis, although less total products were usually detected. In contrast, when similar experiments were conducted with isolated hepatic microsomes and perfused livers, 2,5-DHBA was the primary product from salicylate, and p-tyrosine was the major product from D-phenylalanine. Cytochrome P-450 enzymes can hydroxylate salicylate to produce 2,5-DHBA, and it is likely that phenylalanine hydroxylase produces most of the p-tyrosine detected in hepatic tissues. Thus, although both salicylate and D-phenylalanine are useful probes for hydroxyl radical formation in chemical systems, hydroxylated products formed from enzymatic reactions complicate interpretation of data from both compounds in vivo. 相似文献
10.
T.W. Barrett 《Journal of theoretical biology》1982,99(2):293-307
In Part I (Barrett, 1981), the concept of chemical parametric excitation was reviewed and applied to the process of nerve action potential excitation and regeneration. In the present paper, the chemical reactions involved in muscle contraction and the enzymatic reaction are examined and shown to be examples of chemical parametric excitation.It is demonstrated that in a model biochemical scheme for an enzymatic reaction, the enzyme is activated from a state, X, to a state, , and in this activated state pumps the reaction parametrically. The concept of enzyme is identified with an excited state or state of disequilibrium permitting a release of energy during the dissipation, , in the enzymatic reaction, which is powered by the release of energy in the return to the unexcited state X. The demonstration of parametric excitation relations for chemical systems indicates an explanation for the directionality of energy flow and designates an energy pumping role for an enzyme.In muscle contraction, the role of is played by actomyosin and Ca2+, and the enzymatic reaction is the hydrolysis of ATP. The release of energy caused by this hydrolysis reaction brings about the conformational changes underlying muscle contraction. 相似文献
11.
Anton V. Endutkin Anna V. Yudkina Viktoriya S. Sidorenko 《Journal of biomolecular structure & dynamics》2013,31(17):4407-4418
AbstractTransient protein–protein complexes are of great importance for organizing multiple enzymatic reactions into productive reaction pathways. Base excision repair (BER), a process of critical importance for maintaining genome stability against a plethora of DNA-damaging factors, involves several enzymes, including DNA glycosylases, AP endonucleases, DNA polymerases, DNA ligases and accessory proteins acting sequentially on the same damaged site in DNA. Rather than being assembled into one stable multisubunit complex, these enzymes pass the repair intermediates between them in a highly coordinated manner. In this review, we discuss the nature and the role of transient complexes arising during BER as deduced from structural and kinetic data. Almost all of the transient complexes are DNA-mediated, although some may also exist in solution and strengthen under specific conditions. The best-studied example, the interactions between DNA glycosylases and AP endonucleases, is discussed in more detail to provide a framework for distinguishing between stable and transient complexes based on the kinetic data.Communicated by Ramaswamy H. Sarma 相似文献
12.
trans -[PtCl4(NH3)(thiazole)] (1), trans-[PtCl4(cha)(NH3)] (2), cis-[PtCl4(cha)(NH3)] (3) (cha =cyclohexylamine), and cis-[PtCl4(NH3)2] (4) has been investigatedat 25 °C in a 1.0 M aqueous medium at pH 2.0–5.0 (1) and 4.5–6.8 (2–4) using stopped-flow spectrophotometry. The redox reactions follow the second-order rate law , where k is a pH-dependent rate constant and [GSH]tot the total concentration of glutathione. The reduction takes place via parallel reactions between the platinum(IV) complexes
and the various protolytic species of glutathione. The pH dependence of the redox kinetics is ascribed to displacement of
these protolytic equilibria. The thiolate species GS− is the major reductant under the reaction conditions used. The second-order rate constants for reduction of compounds 1–4 by GS− are (1.43±0.01)×107, (3.86±0.03)×106, (1.83±0.01)×106, and (1.18±0.01)×106 M−1 s−1, respectively. Rate constants for reduction of 1 by the protonated species GSH are more than five orders of magnitude smaller. The mechanism for the reductive elimination
reactions of the Pt(IV) compounds is proposed to involve an attack by glutathione on one of the mutually trans coordinated chloride ligands, leading to two-electron transfer via a chloride-bridged activated complex. The kinetics results
together with literature data indicate that platinum(IV) complexes with a trans Cl-Pt-Cl axis are reduced rapidly by glutathione as well as by ascorbate. In agreement with this observation, cytotoxicity
profiles for such complexes are very similar to those for the corresponding platinum(II) product complexes. The rapid reduction
within 1 s of the platinum(IV) compounds with a trans Cl-Pt-Cl axis to their platinum(II) analogs does not seem to support the strategy of using kinetic inertness as a parameter
to increase anticancer activity, at least for this class of compounds.
Received: 8 December 1999 / Accepted: 15 February 2000 相似文献
13.
L G Fenoll J N Rodríguez-López F García-Sevilla J Tudela P A García-Ruiz R Varón F García-Cánovas 《European journal of biochemistry》2000,267(19):5865-5878
Tyrosinase can act on monophenols because of the mixture of mettyrosinase (Em) and oxytyrosinase (Eox) that exists in the native form of the enzyme. The latter form is active on monophenols although the former is not. However, the kinetics are complicated because monophenols can bind to both enzyme forms. This situation becomes even more complex as the products of the enzymatic reaction, the o-quinones, are unstable and continue evolving to generate o-diphenols in the medium. In the case of substrates such as 4-methoxyphenol, 4-ethoxyphenol and 4-tert-butylphenol, tyrosinase generates o-quinones which become unstable with small constants of approximately < 10-3 s-1. The system evolves from an initial steady state, reached when t-->0, through a transition state towards a final steady state, which is never reached because the substrate is largely consumed. The mechanisms proposed to explain the enzyme's action can be differentiated by the kinetics of the first steady state. The results suggest that tyrosinase hydroxylates monophenols to o-diphenols, generating an intermediate Em-diphenol in the process, which may oxidize the o-diphenol or release it directly into the medium. In the case of o-quinone formation, its slow instability generates o-diphenol which activates the enzymatic system yielding parabolic time recordings. 相似文献
14.
The effect of subinhibitory concentrations (subMICs) of new organic ammonium salts of four homologous series of alkylammonium
bromides (32 compounds) was determined with respect to the induction of lysogenic strain prophage, influence of permeability
reactions in a rabbit skin test and cytotoxic changes of monolayers of Vero cells. The culture filtrates were prepared by
1-d cultivation ofSalmonella typhimurium in a synthetic culture medium under conditions of intensive aeration at 37°C after addition of subinhibitory concentrations
of organic ammonium salts. The results showed that substances of the homologous series of 2-(10-undecenoyloxy)ethyl-alkyldimethylammonium
bromides were characterized by a prophage-inducing effect in lysogenic strain cells. The induction of prophage raised with
rising concentrations of subMICs of the substances, and its titer in the culture filtrates was mostly 4.106 PFU/mL. SubstancesC3, C9 andC12 of the same homologous series had the strongest effect on the permeability reaction in rabbit skin in 1/2 MICs. One-half
MICs of four substances (B14, C3, C12, C14) and 1/4 MICs of substanceA16 influenced cytotoxic changes on Vero cells, the other substances were ineffective. 相似文献
15.
Yajaira Pérez Vilmari López Luis Rivera-Rivera Aracelis Cardona Enrique Meléndez 《Journal of biological inorganic chemistry》2005,10(2):94-104
Three new water soluble titanocene–aminoacid complexes have been synthesized via the reaction of Cp2TiCl2 and two equivalents of aminoacid (L) in methanol, affording [Cp2TiL2]Cl2, L=L-cysteine (2), D-penicillamine (3) and L-methionine (4). These complexes have been characterized by 1H, IR and UV-Vis spectroscopies, elemental analysis and cyclic voltammetry. Kinetic studies of ligand hydrolysis have been monitored at low pH using UV-Vis and 1H NMR spectroscopies to assess their stability in aqueous solution. At low pH, aminoacid ligands are lost one order of magnitude faster than cyclopentadienyl. However, at physiological pH, in Tris buffer solution, the complexes decompose rapidly to form an insoluble titanium compound. The affinity of these complexes to apo-transferrin was also investigated to elucidate how the ancillary aminoacid ligands affect the titanium intake by apo-transferrin.Electronic Supplementary Material Supplementary material is available for this article at 相似文献
16.
T. V. Rogozhina V. V. Rogozhin 《Biochemistry (Moscow) Supplemental Series B: Biomedical Chemistry》2011,5(4):363-368
Reactions of peroxidase oxidation of triftazine and thioproperazine have been investigated in the presence of horseradish
peroxidase using steady state kinetic methods. It has been shown that phenothiazines are slowly oxidizable substrates for
horseradish peroxidase. k
cat and K
m
values have been determined in the range of pH from 4.5 to 7.5. The study of co-oxidation of phenothiazines and o-dianisidine (ODN) revealed that in the presence of aminazine and ODN in the reaction medium both substances follow sequential
oxidation. ODN oxidation was not observed until full conversion of aminazine. At pH 4.5–5.5 thioproperazine bound to the enzyme-substrate
complex and caused anticompetitive inhibition of peroxidase. At pH > 5.5 sequential substrate oxidation with preferential
thioproperazine conversion occurred. In the range of pH from 4.5 to 7.5 triftazine did not influence ODN oxidation. 相似文献
17.
《Biocatalysis and Biotransformation》2013,31(2):94-99
AbstractBiocatalysis with hydroperoxide lyase (HPL) in extracts from Penicillium camemberti, in neat organic solvent media has been investigated. The effects of reaction conditions including organic solvent mixtures, initial water activity (aw) and reaction temperature as well as the effect of the lyoprotectants, KCl and dextran 1 kDa, on HPL activity were studied. The addition of KCl to the enzymatic extract (70:1 protein, w/w) prior to lyophilization, enhanced HPL activity 6.53-fold. In contrast, the presence of dextran at a ratio of 8:1 decreased the enzymatic activity. Using hexane as the reaction medium, with an initial aw of 0.1 and 0.5, the HPL specific activity was determined to be as 6.3 and 65.9 nmol converted 10-HPOD/mg protein/min, for the enzymatic extract without and with KCl present, respectively. Although HPL enzymatic extract with KCl showed a relatively low optimum reaction temperature (45°C) compared to 55°C without KCl, it exhibited a 2.51- and 2.78-fold higher thermal stability at 60 and 80°C, respectively. The kinetic results indicated that the highest HPL catalytic efficiency, Vmax/Km, of 6.58 × 10?2 mL/mg protein/min, was obtained in the presence of KCl. 相似文献
18.
Mitoraj MP Parafiniuk M Srebro M Handzlik M Buczek A Michalak A 《Journal of molecular modeling》2011,17(9):2337-2352
The present study characterizes changes in the electronic structure of reactants during chemical reactions based on the combined
charge and energy decomposition scheme, ETS-NOCV (extended transition state–natural orbitals for chemical valence). Decomposition
of the activation barrier, ΔE
#, into stabilizing (orbital interaction, ΔE
orb, and electrostatic, ΔE
elstat) and destabilizing (Pauli repulsion, ΔE
Pauli, and geometry distortion energy, ΔE
dist) factors is discussed in detail for the following reactions: (I) hydrogen cyanide to hydrogen isocyanide, HCN → CNH isomerization; (II) Diels-Alder cycloaddition of ethene to 1,3-butadiene; and two catalytic processes, i.e., (III) insertion of ethylene into the metal-alkyl bond using half-titanocene with phenyl-phenoxy ligand catalyst; and (IV) B–H bond activation catalyzed by an Ir-containing catalyst. Various reference states for fragments were applied in ETS-NOCV
analysis. We found that NOCV-based deformation densities (Δρ
i) and the corresponding energies ΔE
orb(i) obtained from the ETS-NOCV scheme provide a very useful picture, both qualitatively and quantitatively, of electronic
density reorganization along the considered reaction pathways. Decomposition of the barrier ΔE# into stabilizing and destabilizing contributions allowed us to conclude that the main factor responsible for the existence
of positive values of ΔE
# for all processes (I, II, III and IV) is Pauli interaction, which is the origin of steric repulsion. In addition, in the case of reactions II, III and IV, a significant degree of structural deformation of the reactants, as measured by the geometry distortion energy, plays an
important role. Depending on the reaction type, stabilization of the transition state (relatively to the reactants) originating
either from the orbital interaction term or from electrostatic attraction can be of vital importance. Finally, use of the
ETS-NOCV method to describe catalytic reactions allows extraction of information on the role of catalysts in determination
of ΔE
#. 相似文献
19.
《Biotechnology & genetic engineering reviews》2013,29(1):405-428
Abstract Microreaction technology is an interdisciplinary area of science and engineering. It has attracted the attention of researchers from different fields in the past few years and consequently, several microreactors have been developed. Enzymes are organic catalysts used for the production useful substances in an environmentally friendly way, and have high potential for analytical applications. However, relatively few enzymatic processes have been commercialized because of problems in the stability of enzyme molecule, and the cost and efficiency of the reactions. Thus, there have been demands for innovation in process engineering particularly for enzymatic reactions, and microreaction devices can serve as efficient tools for the development of enzyme processes. In this review, we summarize the recent advances of microchannel reaction technologies and focus our discussion on enzyme microreactors. We discuss the manufacturing process of microreaction devices and the advantages of microreactors compared with the conventional reactors. Fundamental techniques for enzyme microreactors and important applications of this multidisciplinary technology in chemical processing are also included in our topics. 相似文献
20.
Regulation mechanism of excitation energy transfer between phycobilisomes (PBS) and the photosynthetic reaction centres was studied by the state transition techniques in PBS-thylakoid membrane complexes. DCMU, betaine, and N-ethylmaleimide were applied to search for the details of energy transfer properties based on the steady fluorescence measurement and individual deconvolution spectra at state 2 or state 1. The closure of photosystem (PS) 2 did not influence on fluorescence yields of PS1, i.e., energy could not spill to PS1 from PS2. When the energy transfer pathway from PBS to PS1 was disturbed, the relative fluorescence yield of PS2 was almost the same as that of PS2 in complexes without treatment. If PBSs were fixed by betaine, the state transition process was restrained. Hence PBS may detach from PS2 and become associated to PS1 at state 2. Our results contradict the proposed "spill-over" or "PBS detachment" models and support the mobile "PBS model". 相似文献