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At least 883 records · Page 49Linked to original sources
PubMed1994

Synthetic DNA probes to identify members of the Anopheles gambiae complex and to distinguish the two major vectors of malaria within the complex, An. gambiae s.s. and An. arabiensis.

Two cloned DNA sequences, lambda C10 and lambda G12, have been isolated from a female Anopheles gambiae sensu stricto genomic DNA library in lambda EMBL4. The lambda C10 clone hybridized with equal intensity to all five of the six species in the An. gambiae Giles complex tested and was therefore suitable for use as a complex-specific clone. The lambda G12 clone was selected for its ability to distinguish the two major vectors of malaria within the complex, An. gambiae s.s. and An. arabiensis. Use of libraries consisting of only female DNA prevented the isolation of male-specific sequences. Southern blot analysis of the cloned DNA permitted the development of smaller Alu I subclones suitable for sequencing that still retained the original specificities and sensitivities of lambda C10 and lambda G12. Each clone was found to possess a series of repeated sequences in direct tandem array of 92-94 and 68 bases, respectively. A comparison of a number of copies of each of the repetitive sequences within the Alu I subclones enabled the definition of consensus sequences for the repetitive elements in lambda C10 and lambda G12. Based on these consensus sequences, two oligonucleotides of 21 and 23 bases designated pAngsl and pAngss were derived from lambda C10 and lambda G12, respectively. When tested as probes against DNA dot-blots and squash-blots of mosquito specimens, each oligonucleotide retained the same species specificity as the original clones from which they were derived. The nonradioactive, alkaline phosphatase-labeled pAngsl was able to detect as little as 1 ng of target genomic DNA by chemiluminescent detection in a 5-hr autoradiographic exposure. The pAngss probe could detect 5-10 ng of genomic DNA in similar assays. The new probes exhibit great potential for use in An. gambiae complex species identification because they provide both a means of distinguishing the two major vectors of malaria within the complex and of assessing the quality of squashed mosquito samples by providing a means of standardizing hybridization results.

Animals↗
PubMed2003

Complexity in multimedia mass balance models: when are simple models adequate and when are more complex models necessary?

Three environmental multimedia models of varying degrees of complexity are compared to assess when simple models are adequate and when more complex models are advantageous. The simplest model, the level II (L-II) model, assumes all environmental media are at chemical equilibrium, whereas the more complex models treat chemical disequilibrium between well-mixed media (standard level IV [L-IV] model) or the major media are subdivided into separate layers to simulate heterogeneity (high-resolution level IV [HR-IV] model). The three models are compared for their performance in predicting steady-state, regional concentrations; dynamic, local-scale concentrations; and chemical persistence in the environment. The results indicate that the L-IV model often provides adequate regional simulations when chemical emission occurs to air or water. This model also is useful for assessing chemical persistence in both steady-state and dynamic scenarios. More complex models, such as the HR-IV model, are suggested for local-scale, dynamic simulations or when the chemical emission occurs to soil because they better characterize rates of intramedia transport, which can greatly affect the model predictions. The simplest L-II model predicts environmental concentrations that can differ significantly from those of more complex models, but it is useful for establishing partitioning tendencies and for ranking chemicals for their relative persistence in steady-state situations.

Air Movements↗
PubMed1992

Heparin-binding properties of vitronectin are linked to complex formation as illustrated by in vitro polymerization and binding to the terminal complement complex.

Vitronectin (VN, complement S-protein) is a multifunctional protein which participates in cell adhesion, coagulation, fibrinolysis, and protection against complement lysis. VN is incorporated into several complexes, such as the terminal complement complex and thrombin-antithrombin III, and is bound to plasminogen activator inhibitor 1. The present study showed that purified VN spontaneously forms polymers of approximately 1000 kDa with a Stokes radius of 10 nm. The polymers are to a varying extent stabilized by disulfide bonds, but are quite stable even after reduction and alkylation, indicating the importance of noncovalent bonds. Plasma VN circulates mainly as a 65/75-kDa monomer containing a cryptic heparin-binding site which is exposed upon a conformational change induced by different stimuli, such as coagulation, heating, adsorption to surfaces, or exposure to acids, urea, or other denaturating agents. In the present study, VN was demonstrated to expose its heparin-binding site and its conformationally dependent 8E6 epitope when incorporated into the terminal complement complex. We suggest that exposure of the heparin-binding site and a putative hydrophobic binding site of VN are linked events dependent upon the same conformational change. In vivo, complex formation probably induces the heparin-binding site. Such a link might also explain why purified heparin-binding VN spontaneously forms polymers. The heparin-binding site may be involved in the elimination of multimolecular complexes containing VN.

Antibodies, Monoclonal↗
PubMed2004

Chemical and biological evaluation of technetium (I) tricarbonyl complexes with EHIDA and DPD. 99m (I) complexes of EHIDA and DPD.

BACKGROUND: 99mTc-phosphate and 99mTc-IDA complexes, made by the addition of 99mTcO4- to the kits, have been applied to bone and gallbladder imaging respectively, for many years. In this paper, an effort to label DPD and EHIDA with [99mTc(CO)3(H2O)3]+ was carried out. MATERIAL AND METHODS: DPD and EHIDA were synthesised and prepared in kit form in INS "Vinca". A carbonyl labelling agent Isolink (Mallinckrodt Medical B.V.) and a carbonyl precursor (NCRS Demokritos) were applied. The samples of each compound were added to a vial containing 99mTc-carbonyl precursor, in which original pH (10/11) was neutralised to a pH of around 5.5 or 7.5, the same one as the pH of the investigated compounds. After heating, the reaction products were analysed by HPLC equipped with UV and g-detector, with TEAP 0.05 M, methanol and water as solvent. The biological evaluation of 99m99mTc(I)-coordinated compounds, as well as 99mTc-DPD and 99mTc-EHIDA complexes, involved a bio distribution examination on Wistar rats. RESULTS: The results have shown that hydrophilic organometallic [99mTc(CO)3(H2O)3]+ precursor facilitates the formation of Tc (I) complexes with these ligands, based on the tricarbonyltechnetium (I) core. The changes in structure of DPD and EHIDA labelled molecules influenced biological behaviour: 99Tc(CO)3 -DPD did not accumulate in bone (< 1% of the complex was found in the femur), while 99Tc(CO)3-EHIDA has shown slower billiary excretion and faster filtration through the kidneys. DISCUSSION: The results of the labelling of DPD and EHIDA with [99mTc(CO)3(H2O)3]+ and their chemical and biological behaviour, in comparison with the same one for 99mTc-DPD and 99mTc-EHIDA, confirmed that different oxidation states of technetium make the formation of a variety of complexes with quite different behaviour possible.

Animals↗
PubMed1992

Protease composition of exocytosed human skin mast cell protease-proteoglycan complexes. Tryptase resides in a complex distinct from chymase and carboxypeptidase.

We characterized the release and the protease composition of high m.w. complexes released from dispersed human skin mast cells, under conditions that did not disrupt the binding of proteases to proteoglycan. The net percent release ratio of tryptase to histamine, after anti-IgE and calcium ionophore A23187 stimulation was higher than those for chymase or carboxypeptidase. This was explained by the greater cell association of carboxypeptidase and chymase, compared with tryptase, after mast cell degranulation and/or differential cosedimentation of the proteases with mast cells, because treatment of activated mast cells with 1 M NaCl increased the release ratios of chymase and carboxypeptidase more than that of tryptase. Tryptase, after release, was stable in 0.12 M NaCl and had a molecular mass of approximately 200 to 250 kDa, suggesting that it was bound to proteoglycan. We demonstrated that complexes containing chymase and carboxypeptidase were separable from tryptase-containing complexes by gel filtration and by affinity chromatography. First, on fast protein liquid chromatography, released tryptase filtered at a molecular mass of approximately 200 to 250 kDa, compared with chymase and carboxypeptidase at 400 to 560 kDa. Second, by using affinity chromatography with immobilized antitryptase mAb in 0.15 M NaCl, carboxypeptidase and chymase activities were recovered primarily in the effluent and washes of an antitryptase antibody affinity column and cofiltered at 400 to 560 kDa. Tryptase was recovered only in the eluate. Finally, by using potato tuber carboxypeptidase inhibitor-Sepharose affinity chromatography, tryptase activity was found primarily in the effluent and washes, filtered at a molecular mass of 200 kDa on fast protein liquid chromatography, and was stable in 0.12 M NaCl buffer at 37 degrees C. Carboxypeptidase and chymase activities were found primarily in the eluate. These findings suggest that tryptase and carboxypeptidase/chymase reside in distinct macromolecular complexes. Separate complexes containing these proteases may help explain previous ultrastructural observations in which the distributions of chymase and tryptase within a single granule did not always coincide.

Carboxypeptidases↗
PubMed1992

In vitro evidence for direct complexation of ADR-529/ICRF-187 [(+)-1,2-bis-(3,5-dioxo-piperazin-1-yl)propane] onto an existing ferric-anthracycline complex.

ADR-529 protects against anthracycline cardiotoxicity, possibly by preventing free radical induction. We hypothesize that this occurs by ADR-529 forming a ternary anthracycline-iron-ADR-529 complex. This study used 200-MHz Fourier-transformed NMR to demonstrate the ability of ADR-529 to do this. Peak assignments were by proton-correlated spectroscopy and proton-carbon heteronuclear-correlated spectroscopy. Ga3+ served as a probe for Fe3+, and D2O was the system solvent. Doxorubicin and epirubicin were the studied drugs. Proton spectra of multiple combinations (including pure standards as controls) were obtained. Both Ga3+ plus ADR-529 and Ga3+ plus doxorubicin showed evidence of complexation, as seen by appropriate peak shifts and changes in the associated coupling constants. Ga3+ plus ADR-529 plus epirubicin showed complexation different from that of Ga3+ plus ADR-529 or Ga3+ plus doxorubicin and consistent with the proposed structure. We conclude that ADR-529 would be able to form a ternary complex with an existing anthracycline-Fe3+ complex in an isolated aqueous environment.

Antibiotics, Antineoplastic↗
PubMed1991

Thrombin-hirudin complex stability: a comparison with the thrombin-antithrombin III complex.

In the present in vitro study the stabilities of the thrombin-hirudin and the thrombin-antithrombin III complexes were investigated. After incubation of the complexes with free inhibitors the thrombin-antithrombin III levels were determined by ELISA. The thrombin-hirudin complex proved to be stable in the presence of antithrombin III or heparin. However, in the presence of heparin and plasma equivalent concentrations of antithrombin III, the thrombin-hirudin complex dissociated and hirudin was displaced. In contrast, both thrombin-antithrombin III and thrombin-antithrombin III/heparin complexes are very stable even in the presence of a large excess of hirudin.

Antithrombin III↗
PubMed1990

Dual effect of amiodarone on mitochondrial respiration. Initial protonophoric uncoupling effect followed by inhibition of the respiratory chain at the levels of complex I and complex II.

The effects of amiodarone on the respiration of isolated mouse liver mitochondria have been determined. Amiodarone (200 microM) had a biphasic effect on state 4 respiration supported by either glutamate plus malate or succinate. Initially, the respiratory rate was increased. This stimulatory effect was not prevented by oligomycin (an inhibitor of ATP synthase). It was associated with marked accumulation of amiodarone in the mitochondria, and with collapse of the mitochondrial membrane potential. This initial uncoupling effect was followed by a progressive decrease in the state 4 respiration rate, leading eventually to marked inhibition. Preincubation for 5 min with amiodarone (200 microM) also decreased markedly ADP-stimulated (state 3) respiration, ATP production and dinitrophenol-stimulated (uncoupled) respiration supported by glutamate plus malate (which donate electrons to complex I), and respiration supported by succinate (which donate electrons to complex II), but did not affect respiration supported by duroquinol (donating electrons to complex III) or by ascorbate plus N,N,N',N'-tetramethyl-p-phenylenediamine (donating electrons to cytochrome c). Preincubation with amiodarone (150-200 microM) decreased markedly respiration mediated by fatty acids of various chain length and respiration mediated by citrate, a tricarboxylic acid cycle substrate. We conclude that amiodarone has a dual effect on mitochondrial respiration. The initial uncoupling effect is probably due to the entry of protonated amiodarone, releasing a proton in the matrix. Accumulation of amiodarone soon leads to inhibition of the respiratory chain at the levels of complex I and complex II and to decreased ATP formation.

Adenosine Diphosphate↗
PubMed1991

The membrane-bound proteins of periplasmic permeases form a complex. Identification of the histidine permease HisQMP complex.

The membrane-bound proteins of periplasmic transport systems have been hypothesized to form a complex with relatively little experimental support. Here we present experimental evidence that HisQ, HisM, and HisP, the membrane-bound proteins of the periplasmic histidine transport system of Salmonella typhimurium, form such a complex. We have developed antibodies specific to each of these proteins to aid in their characterization. Extractions with urea, alkaline pH, or Triton X-114 show that HisQ and HisM are integral membrane proteins. By these tests HisP displays an unusual behavior, being associated with the membrane whether or not HisQ and HisM are present and despite its hydrophilic sequence. However, the nature of HisPs interaction with the membrane is shown to vary depending on the presence of HisQ and HisM. In their absence, HisP is somewhat peripherally associated with the membrane, while in their presence it binds much more tightly, indicating that it forms a complex in association with HisQ and HisM. This is demonstrated by the coimmunoprecipitation of all three proteins by antibodies directed against any one of them. Chemical cross-linking allowed the characterization of the subunit stoichiometry of the complex as two HisPs to one HisQ and one HisM. Within this complex all three proteins probably contact each other and the two HisPs form a dimer. We hypothesize that HisQ and HisM with their multiple membrane-spanning segments form a "channel" within which the HisP subunits are located.

ATP-Binding Cassette Transporters↗
PubMed1977

Immunologic properties of protein-lipopolysaccharide complexes. I. Antibody response of normal, thymectomized, and nude mice to a lysozyme-lipopolysaccharide complex.

The in vivo antibody response to the lysozyme component of a lysozyme-lipopolysaccharide complex has been investigated in normal, thymectomized and nude mice. The splenic PFC response elicited by the complex in CBA mice is 10- to 20-fold higher than the response elicited by lysozyme admixed with LPS. Both lysozyme-LPS complexes and lysozyme + LPS mixtures prime mice for a subsequent secondary anti-lysozyme response. In contrast, thymectomized mice responded poorly to lysozyme-LPS complexes unless reconstituted with splenic T cells. However, nude mice responded as well as Nu/+ controls to the complex. The PFC response of normal and of nude mice was severely depressed by treatment with anti-lymphocyte serum. These findings suggest that T lymphocytes contribute significantly to the enhanced immune responsiveness associated with LPS administration.

Animals↗
PubMed1995

DnaX complex of Escherichia coli DNA polymerase III holoenzyme. Physical characterization of the DnaX subunits and complexes.

A physical characterization of the tau and gamma subunits of the Escherichia coli DNA polymerase III holoenzyme and their complexes with the delta, delta', chi, and psi subunits is presented. The native molecular mass of the tau and gamma subunits was determined to be 255,000 and 189,000 Da, respectively, by sedimentation equilibrium analytical ultracentrifugation. Both values indicate a tetrameric quaternary structure. The tau and gamma complexes were reconstituted and purified using two different methods. Both complexes assembled readily and were reconstituted at subunit concentrations approaching physiological levels. The stoichiometries of the tau and gamma complexes, as determined by quantitative densitometry of SDS-polyacrylamide gels, were found to be tau 4 delta 1 delta' 1 chi 1 psi 1 and gamma 4 delta 1 delta' 1 chi 1 psi 1. BIAcore analysis demonstrated that the formation of large multiprotein complexes of holoenzyme subunits depends on the presence of the tau subunit; gamma could not substitute. We present a model for a gamma-less form of DNA polymerase III holoenzyme that has asymmetrical structural features that may be responsible for the functional asymmetry observed in holoenzyme. The stoichiometry of the reconstituted DNA polymerase III* component of holoenzyme in this model is (alpha epsilon theta)2DnaX4 delta 1 delta' 1 chi 1 psi 1.

Coenzymes↗
PubMedDate not supplied

[The hierarchy of complexes and compact structures of trivaline with nucleic acids. III. Complexes of trivaline with trinucleotides forms a rod-like structure with length of about 1000 A in solution].

We demonstrated the ability of trivaline in the course of interaction with certain trinucleotides in solution to form extended fibre-like structures with lengths of up to several thousand angstroms. Such structures were observed for complexes of trivaline with both deoxyribo- and ribonucleotides with homopurine, homopyrimidine, or random sequences, with or without terminal 5'-phosphate. A model of organization of such structures is proposed. It is based on tetramer complex of trivaline with short nucleotides, two structural units of which, consisting of trivaline tetramer and two trinucleotides, form the octamer complex. It has three perpendicular axes of symmetry of the second order. The spatial location of bases in this structure is additionally fixed by nucleopeptide interactions. The latter create favourable conditions for arranging hydrogen bonds between trinucleotides belonging to different tetramer complexes and stacking interactions between the bases of each nucleotide. Octamer complexes are able to form regular aggregates in the form of a "stack", consisting of dozens of elementary units. These aggregates can be electron microscopically visualized as extended fibre-like structures.

Microscopy, Electron↗
PubMed1991

Electron spin echo envelope modulation spectroscopy supports the suggested coordination of two histidine ligands to the Rieske Fe-S centers of the cytochrome b6f complex of spinach and the cytochrome bc1 complexes of Rhodospirillum rubrum, Rhodobacter sphaeroides R-26, and bovine heart mitochondria.

Electron spin echo envelope modulation (ESEEM) experiments performed on the Rieske Fe-S clusters of the cytochrome b6f complex of spinach chloroplasts and of the cytochrome bc1 complexes of Rhodospirillum rubrum, Rhodobacter sphaeroides R-26, and bovine heart mitochondria show modulation components resulting from two distinct classes of 14N ligands. At the g = 1.92 region of the Rieske EPR spectrum of the cytochrome b6f complex, the measured hyperfine couplings for the two classes of coupled nitrogens are A1 = 4.6 MHz and A2 = 3.8 MHz. Similar couplings are observed for the Rieske centers in the three cytochrome bc1 complexes. These ESEEM results indicate a nitrogen coordination environment for these Rieske Fe-S centers that is similar to that of the Fe-S cluster of a bacterial dioxygenase enzyme with two coordinated histidine ligands [Gurbiel, R. J., Batie, C. J., Sivaraja, M., True, A. E., Fee, J. A., Hoffman, B. M., & Ballou, D. P. (1989) Biochemistry 28, 4861-4871]. The Rieske Fe-S cluster lacks modulation components from a weakly coupled peptide nitrogen observed in water-soluble spinach ferredoxin. Treatment with the quinone analogue inhibitor DBMIB causes a shift in the Rieske EPR spectrum to g = 1.95 with no alteration in the magnetic coupling to the two nitrogen atoms. However, the ESEEM pattern of the DBMIB-altered Rieske EPR signal shows evidence of an additional weakly coupled nitrogen similar to that observed in the spinach ferredoxin ESEEM patterns.

Animals↗
PubMed1982

Reversible inhibition of the mitochondrial ubiquinol-cytochrome c oxidoreductase complex (complex III) by ethoxyformic anhydride.

The mitochondrial ubiquinol-cytochrome c oxidoreductase (complex III) is inhibited by ethoxyformic anhydride (EFA). The inhibition is readily reversed by hydroxylamine, suggesting the involvement of essential histidyl or possibly tyrosyl residues. The spectrum of ethoxyformylated complex III in the UV region showed a peak at 238 nm, indicative of N-(ethoxyformyl)histidine. Addition of hydroxylamine caused a large decrease of the 238-nm peak, which amounted to 16 mol of (ethoxyformyl)histidine/mol of cytochrome c1. Hydroxylamine addition to ethoxyformylated complex III also caused a small change at about 280 nm, which could be due to reversal of 1.6 O-ethoxyformylated tyrosyl residues/mol of cytochrome c1. Among many inhibitors of the cytochrome bc1 region of the respiratory chain, EFA is the only reagent known to cause reversible inhibition by covalent modification of amino acid residues. The inhibition site of EFA was determined to be between cytochromes b-562 and c1. However, unlike antimycin, which also inhibits in the same region, EFA did not promote the reduction of cytochrome b-566 in particles treated with substrates. In addition, it was found that EFA inhibits proton translocation in the cytochrome bc1 region and is a more effective electron transport inhibitor when added to reduced particles as compared to oxidized particles. These results together with the strong possibility that the EFA target is a histidyl or possibly a tyrosyl residue have been discussed in relation to the mechanism of proton translocation by complex III.

Anaerobiosis↗
PubMed1995

Resolution of the aerobic respiratory system of the thermoacidophilic archaeon, Sulfolobus sp. strain 7. III. The archaeal novel respiratory complex II (succinate:caldariellaquinone oxidoreductase complex) inherently lacks heme group.

An active respiratory complex II (succinate:quinone oxidoreductase) has been purified from tetraether lipid membranes of the thermoacidophilic archaeon, Sulfolobus sp. strain 7. It consists of four different subunits with apparent molecular masses of 66, 37, 33, and 12 kDa on sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The 66-kDa subunit contains a covalently bound flavin, the 37-kDa subunit is a possible iron-sulfur protein carrying three distinct types of EPR-visible FeS cluster, and the 33- and 12-kDa subunits are putative membrane-anchor subunits, respectively. While no heme group is detected in the purified complex II, it catalyzes succinate-dependent reduction of ubiquinone-1 and 2,6-dichlorophenolindophenol in the absence of phenazine methosulfate. The respiratory complex II of Sulfolobus sp. strain 7 appears to be novel in that it functions as a true succinate:caldariellaquinone oxidoreductase, although inherently lacking any heme group. This further indicates that the heme group of several respiratory complexes II may not be involved in the redox intermediates of the electron transfer from succinate to quinone.

Amino Acid Sequence↗
PubMed1989

Coevolution of the major histocompatibility complex and the t-complex in the mouse. II. Modification of response to sharing of histocompatibility antigens.

Selective pressures imposed by high complementarity associations between the major histocompatibility complex (MHC) and the t-complex on a locus that modifies the expression of prezygotic and postzygotic incompatibility are investigated through the analysis of a quantitative model. Sharing of MHC antigens between mates or between mother and offspring elicits weak inhibition of conception or gestation. In the presence of high complementarity associations between the MHC and the t-complex, weak incompatibility depresses the mean fitness of the population. Nevertheless, natural selection favors the enhancement of the expression of incompatibility if the number of antigens associated with the +-haplotype exceeds the number associated with the t-haplotype by a sufficient margin. Under absolute linkage between the modifier locus and the t-complex, the number associated with the +-haplotype need only be greater than the number associated with the t-haplotype. In the absence of linkage, a twofold difference is sufficient to ensure the initial increase of modifier alleles that intensify the expression of incompatibility.

Alleles↗
PubMed1997

Biogenesis of eukaryotic 20S proteasomes: the complex maturation pathway of a complex enzyme.

Eukaryotic 20S proteasomes harbor a remarkably complex architecture and unique proteolytic properties. Its catalytic mechanism places this enzyme in a new kind of protease family. The recently solved crystal structure of the yeast 20S complex, along with elucidation of the maturation pathway of human proteasomes, has allowed insight into structure/function relationships. Although not all of the unusual enzymatic properties such as broad substrate specificity, predominant generation of peptides with a specific size, or susceptibility to activating complexes can be explained in detail, knowledge of the structure provides important hints for an explanation of underlying mechanisms. Except for ribosome biogenesis, the complexity of eukaryotic proteasome maturation is without precedence. It is a slow process that involves a series of precisely ordered events. Proteasome structure formation is characterized by an initial cooperative formation of an alpha ring matrix, providing docking sites for a defined subset of beta subunits. Subsequent structural rearrangement allows the residual subunits to bind, followed by dimerization of two half-proteasomes. The prosequences of beta subunits exert specific functions during this process and are removed by cis- and trans-autocatalysis, most likely in the completely assembled proteasome cylinder.

Animals↗
PubMed1994

Appearance of type 1, 2, and 3 light-harvesting complex II and light-harvesting complex I proteins during light-induced greening of barley (Hordeum vulgare) etioplasts.

Monospecific antibodies directed against typical domains of type 1, 2, and 3 light-harvesting complex (LHC) II apoproteins have been used (a) to identify these apoproteins on denaturing sodium dodecyl sulfate gels of barley (Hordeum vulgare) thylakoids, (b) to determine their distribution between grana and stroma membranes, and (c) to follow their accumulation during light-induced greening of etioplasts. In addition, we have studied the light-induced assembly of chlorophyll-protein complexes with a native green gel system (K.D. Allen, L.A. Staehelin [1991] Anal Biochem 194: 214-222). Western blot analysis of the three major LHCII apoprotein bands has identified the highest molecular mass band at 27.5 kD as containing the type 2 LHCII apoproteins, the middle band at 26.9 kD as containing the type 1 LHCII apoproteins, and the lowest band at 26.0 kD as containing the type 3 LHCII apoproteins. During light-induced greening of 6-d-old etiolated barley seedlings, the type 1, 2, and 3 LHCII apoproteins accumulate simultaneously and at similar rates but appear somewhat sooner (< 4 h) in thylakoids from apical than from basal (4-8 h) leaf segments. LHCI polypeptides accrue with similar kinetics, whereas the 33-kD oxygen-evolving complex polypeptides can be detected already in the 0-h light samples. During the most rapid phase of thylakoid development (8-24 h), two slightly larger (28.3 and 28.7 kD) type 2 LHCII apoproteins (precursor intermediates?) also accumulate in the thylakoids. No corresponding higher molecular mass forms of type 1 and 3 LHCII apoproteins could be detected. It is interesting that differences are still apparent in the composition of chlorophyll-protein complexes of light-control plants and those of etiolated plants greened for 8 d.

Amino Acid Sequence↗