RESUMO
MOMENT is a 53 kbyte program written in Borland TurboPascal with Borland Turbo Graphics, which will run on IBM PC-compatible machines. The program reads protein sequence files and calculates the hydrophobic moment of user-defined segments. The values produced can be displayed in the form of a scan through the sequence, as vector diagrams and helical wheels, as plots of hydrophobic moment versus hydrophobicity, or as hydrophobic moment as a function of angle.
Assuntos
Proteínas/química , Software , Algoritmos , Sequência de Aminoácidos , Gráficos por Computador , Conformação ProteicaRESUMO
The problem of mapping the positions of the unique binding sites of several monoclonal antibodies on a linear protein structure is considered. Data giving the incidence of binding of individual antibodies to fragments of the protein obtained from it by the incomplete chemical or enzymatic digestion are used to formulate a series of linear programming problems. The solution to these problems shows which orderings of binding sites are possible, and gives upper and lower bounds for the relative positions of the sites.
Assuntos
Anticorpos , Mapeamento de Peptídeos/métodos , Proteínas/química , Proteínas/imunologia , Software , Algoritmos , Sítios de Ligação , Fragmentos de Peptídeos/química , Fragmentos de Peptídeos/imunologiaRESUMO
A series of amphiphilic polymethlyenecarboxymaleimides has been synthesized for use as sulfhydryl reagents applicable to membrane proteins. Physical properties of the compounds which are relevant to their proposed mode of action have been determined. By comparing rates of reaction in aqueous and aprotic solvents, the compounds have been shown to react exclusively with the thiolate ion. The effects of the reagents on three membrane-associated proteins are reported, and in two cases a comparative study has been made of the effects on the proteins in the absence of membranes. A mechanism is proposed whereby the reagents are anchored at the lipid/water interface by the negatively charged carboxyl group, thus sitting the reactive maleimide in a plane whose depth is defined by the length of the reagent. Supporting evidence for this model is provided by the inability of the reagents to traverse membranes, and variation of their inhibitory potency with chain length when the proteins are embedded in the membrane, but not when extracted into solution. As examples of general use of the reagents to probe sulfhydryl groups in membrane proteins, the reagents have been used to (a) determine the depths in the membrane at which two populations of sulfhydryl groups occur in the mitochondrial phosphate transporter; (b) locate a single sulfhydryl associated with the active site of D-beta-hydroxybutyrate dehydrogenase in the inner mitochondrial membrane; (c) examine sulfhydryl groups in the D-3-glyceraldehyde phosphate dehydrogenase associated with the human red blood cell membrane.
Assuntos
Maleimidas/metabolismo , Proteínas de Membrana/metabolismo , Animais , Desidrogenases de Carboidrato/metabolismo , Membrana Eritrocítica/metabolismo , Hidroxibutirato Desidrogenase/metabolismo , Técnicas In Vitro , Maleimidas/síntese química , Maleimidas/química , Mitocôndrias Hepáticas/metabolismo , Fosfatos/metabolismo , Fosfoglicerato Desidrogenase , Ratos , Partículas Submitocôndricas/metabolismo , Compostos de Sulfidrila/metabolismoRESUMO
The amino acid sequences of phytochrome from Avena sativa, Oryza sativa, Curcurbita pepo, Pisum sativum and Arabidopsis thaliana have been analyzed with a variety of computer programs, with a view to identifying areas of the protein which contribute to the properties of this photoreceptor. A region at the C-terminus has been shown to be amphiphilic, and by analogy with surface-seeking peptides, may be responsible for interaction of phytochrome with lipid bilayers. Possible targeting sequences in phytochromes have been identified, including a series of four basic residues which correspond to those responsible for transport of nuclear-located proteins. Sites capable of post-translational modification have been found in monocot sequences, but not in dicot sequences. Areas of the phytochrome molecule which are exposed on the surface of the protein, and which are therefore capable of interaction with other cellular macromolecules, have been identified. Analogies with other biliproteins have been used to define minimum chromophore-protein interactions. Possible enzymic activities associated with phytochromes have been discussed with respect to local amino acid sequence similarity with enzymes.
Assuntos
Fitocromo/química , Plantas/genética , Sequência de Aminoácidos , Dados de Sequência Molecular , Fitocromo/genética , Conformação Proteica , Homologia de Sequência do Ácido Nucleico , Software , Especificidade da Espécie , Difração de Raios XRESUMO
The properties of the components of the mitochondrial ATPase which interact with modulators of energy transduction have been examined. The chromatographic behavior and the size of the components which bind trialkyl tins, carbodiimides and uncouplers, have been shown to be different. However, they all appear to be proteolipids with apparent molecular weights around 10,000. On this basis it is proposed that these inhibitors act at different sites in the membrane sector of the ATP synthase of rat liver mitochondria.
Assuntos
Carbonil Cianeto m-Clorofenil Hidrazona , Mitocôndrias Hepáticas/enzimologia , Nitrilas , ATPases Translocadoras de Prótons/metabolismo , Animais , Sítios de Ligação , Carbonil Cianeto m-Clorofenil Hidrazona/análogos & derivados , Carbonil Cianeto m-Clorofenil Hidrazona/metabolismo , Dicicloexilcarbodi-Imida/metabolismo , Técnicas In Vitro , Membranas Intracelulares/enzimologia , Nitrilas/metabolismo , Ligação Proteica , ATPases Translocadoras de Prótons/antagonistas & inibidores , Ratos , Partículas Submitocôndricas/enzimologia , Compostos de Trialquitina/metabolismo , Desacopladores/metabolismoAssuntos
Proteínas de Transporte/metabolismo , Mitocôndrias Hepáticas/metabolismo , Mitocôndrias/metabolismo , Pirrolidinonas/farmacologia , Compostos de Sulfidrila/metabolismo , Animais , Proteínas de Transporte/antagonistas & inibidores , Dípteros/metabolismo , Etilmaleimida/farmacologia , Ácidos Graxos/farmacologia , Membranas Intracelulares/metabolismo , Dilatação Mitocondrial/efeitos dos fármacos , Músculos/metabolismo , Proteínas de Ligação a Fosfato , Ratos , Relação Estrutura-AtividadeAssuntos
Adenosina Trifosfatases/antagonistas & inibidores , Carbodi-Imidas/metabolismo , Óxidos N-Cíclicos/metabolismo , Dicicloexilcarbodi-Imida/metabolismo , Mitocôndrias Cardíacas/metabolismo , Compostos Orgânicos de Estanho/farmacologia , Compostos de Trialquitina , Adenosina Trifosfatases/metabolismo , Animais , Sítios de Ligação , Bovinos , Espectroscopia de Ressonância de Spin Eletrônica , Técnicas In Vitro , Mitocôndrias Cardíacas/efeitos dos fármacos , Ligação ProteicaAssuntos
Adenosina Trifosfatases/metabolismo , Carbodi-Imidas/farmacologia , Dicicloexilcarbodi-Imida/farmacologia , Mitocôndrias/enzimologia , Saccharomyces cerevisiae/enzimologia , Espectroscopia de Ressonância de Spin Eletrônica , Membranas Intracelulares/enzimologia , Substâncias Macromoleculares , Mitocôndrias/efeitos dos fármacos , Mutação , Oligomicinas/farmacologia , Saccharomyces cerevisiae/efeitos dos fármacos , Especificidade da Espécie , Venturicidinas/farmacologiaAssuntos
Adenosina Trifosfatases/isolamento & purificação , Bactérias/enzimologia , Cloroplastos/enzimologia , Mitocôndrias Cardíacas/enzimologia , Mitocôndrias/enzimologia , Partículas Submitocôndricas/enzimologia , Animais , Bovinos , Membranas Intracelulares/enzimologia , Métodos , Micrococcus/enzimologia , Plantas/enzimologia , Rodopseudomonas/enzimologia , Rhodospirillum rubrum/enzimologia , Solubilidade , Especificidade da EspécieAssuntos
Adenosina Trifosfatases/metabolismo , Trifosfato de Adenosina/metabolismo , Cloroplastos/enzimologia , Cromatóforos/enzimologia , Escherichia coli/enzimologia , Mitocôndrias/enzimologia , Fosfotransferases/metabolismo , Animais , Bovinos , Membrana Celular/enzimologia , Membranas/enzimologia , Ácidos Oleicos , Especificidade de Órgãos , Compostos Organofosforados , Especificidade da Espécie , Relação Estrutura-AtividadeRESUMO
1. The synthesis of dibutylchloromethyltin chloride, a new covalent inhibitor of the mitochondrial ATP synthase [oligomycin-sensitive ATPase (adenosine triphosphatase)] complex is described, together with a method for preparing dibutylchloro[(3)H]methyltin chloride. 2. Studies with the yeast mitochondrial oligomycin-sensitive ATPase complex show that dibutylchloromethyltin chloride inhibits both the membrane-bound enzyme and also the purified Triton X-100-dispersed preparation. 3. F(1)-ATPase is not inhibited even at 500nmol of dibutylchloromethyltin chloride/mg of protein, and the general inhibitory properties are similar to those of triethyltin, oligomycin and dicyclohexylcarbodi-imide, known energy-transfer inhibitors of oxidative phosphorylation. 4. Binding studies with yeast submitochondrial particles show that dibutylchloromethyltin chloride antagonizes the binding of triethyl[(113)Sn]tin, indicating that there is an interaction between the two inhibitor-binding sites. 5. Unlike triethyltin, inhibition by dibutylchloromethyltin chloride is due to a covalent interaction which titrates a component of the inner mitochondrial membrane present at a concentration of 8-9nmol/mg of protein. 6. All of the labelled component can be extracted with chloroform/methanol (2:1, v/v), and sodium dodecyl sulphate/polyacrylamide-gel electrophoresis of the chloroform/methanol extract indicates that the labelled component has an apparent mol.wt. of 6000-8000. However, t.l.c. reveals the presence of only one labelled component which is lipophilic and non-protein and is distinct from the free inhibitor, mitochondrial phospholipids and the dicyclohexylcarbodi-imide-binding protein (subunit 9). 7. Inhibition of mitochondrial ATPase and oxidative phosphorylation is correlated with specific interaction with a non-protein lipophilic component of the mitochondrial inner membrane which is proposed to be a co-factor or intermediate of oxidative phosphorylation.