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1.
With the aid of tartryl-bis--aminocaprylazide artificial dimers were produced from F actin from rabbit striated muscle. These derivatives will not polymerize by themselves but are able to copolymerize fully with native G actin. By modification of a single side chain per dimer, this copolymerization was completely inhibited. The dimers are able to activate subfragment I ATPase of myosin and bind to DNase I with inactivation of the enzyme in the same manner as native G actin. Within the dimer, one ADP is immobilized and will exchange against ATP extremely slowly. The dimers do not bind to the mushroom toxin phalloidin.  相似文献   
2.
Zusammenfassung Die Chemodifferenzierung der Herzmuskulatur von Ratte (215 Tiere) und Meerschweinchen (180 Tiere) wird untersucht und zur Morphodifferenzierung und elektrophysiologisch nachweisbaren Funktionsentwicklung in Beziehung gesetzt. Ferner wird die Entwicklung der Arbeitsmuskulatur mit der des Reizleitungssystems verglichen. Prinzipiell verhält sich die Herzentwicklung bei Ratte und Meerschweinchen ähnlich, doch bestehen erhebliche Unterschiede im Terminplan der Entwicklung. Bei der Ratte erfolgen wesentliche Schritte der Herzentwicklung nach der Geburt, beim Meerschweinchen ist die Entwicklung etwa zur Zeit der Geburt abgeschlossen. In der frühen Embryonalzeit ist die Herzmuskulatur reich an Glykogen, aber arm an Enzymen des oxidativen Stoffwechsels (Bernsteinsäuredehydrogenase, Cytochromoxidase) und -Hydroxibuttersäuredehydrogenase. Kapillaren fehlen. Dann — bei der Ratte etwa ab 12. Embryonaltag — beginnt der Glykogenbestand der Arbeitsmuskulatur abzunehmen. Zunächst werden die subepikardial gelegenen Schichten betroffen. Von hier schreitet die Glykogenverminderung nach innen fort. In den glykogenarm gewordenen Zonen vermehrt sich der Bestand an Atmungsfermenten und Kapillaren. Die Chemodifferenzierung in der Kammermuskulatur erfolgt grundsätzlich von außen nach innen. Parallel hierzu verläuft die Strukturentwicklung der Herzmuskelzellen und es kommt zu elektrophysiologisch nachgewiesenen Änderungen in der Permeabilität der Herzmuskelzellmembranen. Abgeschlossen ist die Entwicklung bei der Ratte nach färberisch-lichtmikroskopischen Befunden in der Mitte der 2. Lebenswoche, nach histochemischen Befunden in der 4. Lebenswoche, nach Maßgabe elektrophysiologischer Beobachtungen nach dem 31. Lebenstag. Die Vorhofmuskulatur ist mit Ausnahme frühembryonaler Stadien stets reicher an Glykogen und ärmer an Atmungsfermenten als die Kammermuskulatur. — Das Reizleitungssystem durchläuft eine eigene Entwicklung. Ursprungsgewebe für das Atrioventricularsystem ist der atrioventriculäre Muskelring. Von hieraus wachsen spezifische Fasern in die Kammermuskulatur vor. Sie unterscheiden sich histochemisch von vornherein von der Arbeitsmuskulatur.
Summary The present study deals with the chemodifferentiation of the cardiac muscle in rats (215 animals) and Guinea pigs (180 animals). The results obtained are compared with the morphological differentiation and the functional development, as determined by electrophysiological methods. Finally, the development of the cardiac muscle is compared with the development of the conducting system. Fundamentally the development as such is the same in rats and Guinea pigs; however, there are striking differences as far as the schedule for the development is concerned. In rats, important steps in the development of the heart take place after birth, where as in Guinea pigs the development is terminated at approximately the time of birth. In the early embryonic stages the cardiac muscle has a high content of glycogen, but it is poor in enzymes of the oxidative metabolism (succinate dehydrogenase, cytochrome oxidase) and -hydroxibutyricaciddehydrogenase. There are no capillaries. Approximately from the 12th embryonic day onwards a decrease of the glycogen content is observed in the cardiac muscle of rats. The first layers to undergo this change are the subepicardial layers. From there it progresses to the innermost layers. The activity of the respiratory enzymes and the number of the capillaries increases in the areas where the glycogen content is now relatively low. On principle the chemodifferentiation of the ventricular mucsle progresses always from the outermost to the innermost layer. The structural development of the cells of the cardiac muscle goes parallel with it; at the same time changes in the permeability of the membranes of cardiac muscle cells are demonstrable by electro-physiological methods. According to light microscopical findings the development in rats is terminated in the middle of the second week of life, according to histochemical findings in the 4th week of life, electrophysiologically after the 31st day of life. It seems to be a rule that apart from the early embryonic stages the auricular muscle is richer in glycogen and poorer in respiratory enzymes than the ventricular muscle. The conducting system has a separate pattern of development. The initial form of the atrioventricular system is the atrio-ventricular muscular ring. From there specific fibres penetrate into the ventricular musculature. Histochemically they are a priori different from the cardiac muscle.


Mit Unterstützung durch die Deutsche Forschungsgemeinschaft.

Stipendiatin der Humboldt-Stiftung.

Frau Prof. Berta Scharrer mit herzlichem Glückwunsch zum 60. Geburtstag gewidmet.  相似文献   
3.
The N-terminal 1-34 fragments of the parathyroid hormone (PTH) and parathyroid hormone-related protein (PTHrP) elicit the full spectrum of bone-related biological activities of the intact native sequences. It has been suggested that the structural elements essential for bioactivity are two helical segments located at the N-terminal and C-terminal sequences, connected by hinges or flexible points around positions 12 and 19. In order to assess the relevance of the local conformation around Gly(12) upon biological function, we synthesized and characterized the following PTH(1-34) analogues containing Aib residues: (I) A-V-S-E-I-Q-F-nL-H-N-Aib-G-K-H-L-S-S-nL-E-R-V-E-Nal-L-R-K-K-L-Q-D-V-H-N-Y-NH(2) ([Nle(8,18), Aib(11), Nal(23),Tyr(34)]bPTH(1-34)-NH(2)); (II) A-V-S-E-I-Q-F-nL-H-N-L-Aib-K-H-L-S-S-nL-E-R-V-E-Nal-L-R-K-K-L-Q-D-V-H-N-Y-NH(2) ([Nle(8,18), Aib(12),Nal(23),Tyr(34)]bPTH(1-34)-NH(2)); (III) A-V-S-E-I-Q-F-nL-H-N-L-G-Aib-H-L-S-S-nL-E-R-V-E-Nal-L-R-K-K-L-Q-D-V-H-N-Y-NH(2) ([Nle(8,18), Aib(13), Nal(23),Tyr(34)]bPTH(1-34)-NH(2)); (IV) A-V-S-E-I-Q-F-nL-H-N-Aib-Aib-K-H-L-S-S-nL-E-R-V-E-Nal-L-R-K-K-L-Q-D-V-H-N-YNH(2) ([Nle(8,18), Aib(11,12), Nal(23),Tyr(34)]bPTH(1-34)-NH(2)); (V) A-V-S-E-I-Q-F-nL-H-N-L-Aib-Aib-H-L-S-S-nL-E-R-V-E-Nal-L-R-K-K-L-Q-D-V-H-N-Y-NH(2) ([Nle(8,18), Aib(12,13),Nal(23),Tyr(34)]bPTH(1-34)-NH(2)). (nL= Nle; Nal= L-(2-naphthyl)-alanine; Aib= alpha-amino-isobutyric acid.) The introduction of Aib residues at position 11 in analogue I or at positions 11 and 12 in analogue IV resulted in a 5-20-fold lower efficacy and a substantial loss of binding affinity compared to the parent compound [Nle(8,18), Nal(23),Tyr(34)]bPTH(1-34)-NH(2). Both binding affinity and adenylyl cyclase stimulation activity are largely restored when the Aib residues are introduced at position 12 in analogue II, 13 in analogue III, and 12-13 in analogue V. The conformational properties of the analogues in aqueous solution containing dodecylphosphocholine micelles were studied by CD, two-dimensional (2D) NMR and computer simulations. The results indicated the presence of two helical segments in all analogues, located at the N-terminal and C-terminal sequences. Insertion of Aib residues at positions 12 and 13, or of Aib dyads at positions 11-12 and 12-13, enhances the stability of the N-terminal helix of all analogues. In all analogues the Aib residues are included in the helical segments. These results confirmed the importance of the helical structure in the N-terminal activation domain, as well as of the presence of the Leu(11) hydrophobic side chain in the native sequence, for PTH-like bioactivity.  相似文献   
4.
5.
Zusammenfassung Die Purkinjefasern von Rind, Kalb, Schwein, Ziege, Hund und Katze zeichnen sich durch eine mehr oder weniger intensive positive Perjodsäure-Schiff-Reaktion aus, welche die zytoplasmatischen Abschnitte und zum Teil die Querstreifung der peripheren Fibrillen deutlich darstellt. Die Arbeitsmuskulatur zeigt dagegen wenige, hauptsächlich in Form von granulären Querreihen lokalisierte PJS-positive Substanzen, die sehr fixierungsabhängig sind. Die Millon-Reaktion ist in den Purkinjefasern sehr schwach, in der Arbeitsmuskulatur deutlich positiver. Sie ist an die fibrillären Faserteile gebunden. Nucleinsäuren fehlen. Von den untersuchten Fermenten ist nur saure Phosphatase mit schwachen Reaktionsintensitäten nachweisbar.Die intensive PJS-Reaktion in den Purkinjefasern beruht auf Grund der histochemischen Spezifitätsuntersuchungen auf reichem Glykogenvorkommen. Jedoch unterscheidet sich das Glykogen des Reizleitungssystems histochemisch durch seine Säurefestigkeit und relative Wasserunlöslichkeit von dem anderer glykogenreicher Organe (Arbeitsmuskulatur, Leber). Außerdem nimmt die PJS-Reaktionsintensität durch Hyaluronidasevorbehandlung ab.Die Ursachen des besonderen Glykogenverhaltens werden diskutiert.Durchgeführt mit dankenswerter Unterstützung seitens der Deutschen Forschungsgemeinschaft.  相似文献   
6.
Characterization of synapsin I binding to small synaptic vesicles   总被引:34,自引:0,他引:34  
The binding of synapsin I, a synaptic vesicle-associated phosphoprotein, to small synaptic vesicles has been examined. For this study, synapsin I was purified under nondenaturing conditions from rat brain, using the zwitterionic detergent 3-[(3-cholamidopropyl)dimethylammonio]-1-propanesulfonate (CHAPS), and characterized. Small synaptic vesicles were purified from rat neocortex by controlled pore glass chromatography as the last purification step, and binding was characterized at an ionic strength equivalent to 40 mM NaCl. After removal of endogenous synapsin I, exogenous dephospho-synapsin I bound with high affinity (Kd, 10 +/- 6 nM) to synaptic vesicles. The binding saturated at 76 +/- 40 micrograms synapsin I/mg of vesicle protein, which corresponded to the amount found endogenously in purified vesicles. Synapsin I binding exhibited a broad pH optimum around pH 7. Other basic proteins, specifically myelin basic protein and histone H2b, did not compete with synapsin I for binding to vesicles. Other membranes purified from rat brain and membranes derived from human erythrocytes did not show the high affinity binding site for synapsin I found in vesicles. The binding of three different forms of phosphosynapsin I to vesicles was investigated. Synapsin I, phosphorylated at sites 2 and 3 by purified calcium/calmodulin-dependent protein kinase II, bound with a 5-fold lower affinity to the vesicles than did dephospho-synapsin I. In contrast, synapsin I, phosphorylated at site 1 by purified catalytic subunit of cAMP-dependent protein kinase, bound with an affinity close to that of dephospho-synapsin I. Synapsin I phosphorylated on all three sites bound to the vesicles with an affinity comparable to that of synapsin I phosphorylated on sites 2 and 3. Under conditions of higher ionic strength (150 mM NaCl equivalent), synapsin I bound with a 5-fold lower affinity to vesicles, and no effect of phosphorylation on binding was observed under these conditions.  相似文献   
7.
Zusammenfassung Untersucht wurde der Sinusknoten von 141 Rinderherzen (davon 11 Embryonen und 50 Kälber), 25 Schweinen und 10 Herzen anderer Säuger (5 Schafe, 2 Kaninchen, 2 Katzen, 1 Hund) sowie von 29 menschlichen Herzen verschiedenen Alters.Der Sinusknoten (SK) aller Spezies ist glykogenreich; die Vorhofsmuskulatur (VM) ist vergleichsweise glykogenarm. Bei Rinderkeimlingen tritt die Glykogenvermehrung im Knotengewebe gegenüber der VM ab einer Embryonallänge von 47 cm auf.Fermenthistochemisch zeigt sich, daß im SK von Rind und Schwein nicht nur die Enzyme des oxidativen Stoffwechsels, sondern auch die der Glykolyse schwächer als in der VM reagieren. Hierbei überwiegt in beiden Herzmuskelarten die Glykolyse etwas. — Das LDH-Isozymmuster gleicht sich in SK und VM weitgehend, ebenso die Aktivität der G6P-DH und die der lysomalen Enzyme. — Die Fermente des Glykogenmetabolismus reagieren im Knotengewebe in Übereinstimmung mit seinem höheren Glykogengehalt stärker als in der VM. — Die cholinerge Nervenfaserdichte ist im SK von Rind und Schwein höher als in der VM.Entsprechend dem geringeren Stoffwechsel ist die Kapillar Versorgung des SK beim Rind geringer als die des Vorhofs. Der prozentuale Volumenanteil der Kapillaren am Gesamtvolumen des SK verhält sich zu dem der VM wie 13. Der Radius eines Gewebszylinders, der von einer Kapillare versorgt wird, beträgt im SK 19,9 m, im Vorhof aber 10,9 [im.
On the histochemistry and capillary supply of the sinatrial node
Summary The sinatrial node (SA node) was investigated in the heart of 141 cattle (among which were 11 embryos and 50 calves), 25 pigs, 5 sheep, 2 rabbits, 2 cats, 1 dog, and 29 men of different age.The SA node of all species is rich in glycogen; in the atrial muscle its amount is always lower. Comparing the fetal SA node of cattle with the working myocardium, glycogen increases in the former tissue with an embryonic length of 47 cm.Histochemically in the SA node of cattle and pigs the activities of oxidative as well as of glycolytic enzymes are lower than in the ordinary muscle cells; but in both heart muscle systems the pathway of Embden-Meyerhof seems to predominate.—The LDH-isoenzyme patterns of the pacemaker region and working myocardium resemble one another. This is also true for the activity of G6P-DH and lysosomal enzymes.—According to the higher amount of glycogen the enzymes of the glycogen metabolism are more active in the SA node than in the atrial muscle.—In comparison with the working myocardium the number of cholinergic nerve fibers is somewhat higher in the nodal tissue.In agreement with the reduced overall metabolism the capillary supply of the cow's SA node is lower than that of the atrial muscle. The ratio between the partial volume of the capillaries and the total volumes of the SA node and working myocardium is 13. On the average the radius of a tissue cylinder being supplied by one capillary runs up to 19.9 m in the SA node, but only to 10.9 m in the atrial muscle.The partial volume of the connective tissue in the SA node of cattle, calves, and men exhibits strong individual changes. An increase of connective tissue in the SA node of humans appears around the 50th year of life.


Mit Unterstützung durch die Deutsche Forschungsgemeinschaft.  相似文献   
8.
9.
10.
The 1-34 N-terminal fragments of human parathyroid hormone (PTH) and PTH-related protein (PTHrP) elicit the full spectrum of bone-relevant activities characteristic of the intact hormones. The structural elements believed to be required for receptor binding and biological activity are two helical segments, one N-terminal and one C-terminal, connected by hinges or flexible points located around positions 12 and 19. To test this hypothesis, we synthesized and characterized the following analogues of PTH-(1-34), each containing single or double substitutions with beta-amino acid residues around the putative hinge located at position 12: I. [Nle(8,18),beta-Ala(11,12),Nal(23),Tyr(34)]bPTH-(1-34)NH(2); II. [Nle(8,18),beta-Ala(12,13),Nal(23),Tyr(34)]bPTH-(1-34)NH(2); III. [Nle(8,18),beta-Ala(11),Nal(23),Tyr(34)]bPTH-(1-34)NH(2); IV. [Nle(8,18),beta-hLeu(11),Nal(23),Tyr(34)]bPTH-(1-34)NH(2); V. [Nle(8,18),beta-Ala(12), Nal(23),Tyr(34)]bPTH-(1-34)NH(2); VI. [Nle(8,18),beta-Ala(13), Nal(23),Tyr(34)]bPTH-(1-34)NH(2) (beta-hLeu = beta-homo-leucine; beta-Ala = beta-alanine; Nal = L-2-naphthyl-alanine; Nle = norleucine). Analogues I and III exhibit very low binding affinity and are devoid of adenylyl cyclase activity. Analogue II, despite its very low binding capacity is an agonist. Biological activity and binding capacity are partially restored in analogue IV, and completely restored in analogues V and VI. The conformational properties of the analogues were investigated in aqueous solution containing dodecylphosphocholine (DPC) micelles as a membrane-mimetic environment using CD, 2D-NMR, and molecular dynamics calculations. All peptides fold partially into the alpha-helical conformation in the presence of DPC micelles, with a maximum helix content in the range of 30-35%. NMR analysis reveals the presence of two helical segments, one N-terminal and one C-terminal, as a common structural motif in all analogues. Incorporation of beta-Ala dyads at positions 11,12 and 12,13 in analogues I and II, respectively, enhances the conformational disorder in this portion of the sequence but also destabilizes the N-terminal helix. This could be one of the possible reasons for the lack of biological activity in these analogues. The partial recovery of binding affinity and biological activity in analogue IV, compared to the structurally similar analogue III, is clearly the consequence of the reintroduction of Leu side-chain of the native sequence. In the fully active analogues V and VI, the helix stability at the N-terminus is further increased. Taken together, these results stress the functional importance of the conformational stability of the helical activation domain in PTH-(1-34). Contrary to expectation, insertion of a single beta-amino acid residue in positions 11, 12, or 13 in analogues III-VI does not favor a disordered structure in this portion of the sequence.  相似文献   
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