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91.
The efflux of 20 amino acids, induced by either high K+ concentration or veratrine, was determined in pigeon tectal slices. Ca2+-dependent, K+-induced release of beta-alanine, gamma-aminobutyric acid (GABA), and glutamate was observed. Veratrine caused release of the same amino acids plus glycine in a tetrodotoxin-sensitive manner. beta-Alanine had a strong inhibitory effect on the activity of tectal neurons which was blocked by strychnine but not by bicuculline. The results indicated a transmitter function for beta-alanine in the optic tectum, and were consistent with the previously proposed transmitter role of GABA and glutamate in this structure.  相似文献   
92.
Tyrosine hydroxylase was purified from bovine corpus striatum. The native enzyme had a half-life of 15 +/- 3 min at 50 degrees C. Phosphorylation of tyrosine hydroxylase with protein kinase purified from both corpus striatum and heart activated the enzyme, but activity was rapidly lost with additional preincubation of the enzyme at 30 degrees C. Thermal denaturation studies indicated that phosphorylated tyrosine hydroxylase had a half-life of 5 +/- 2 min at 50 degrees C  相似文献   
93.
94.
The genetic variability of membrane proteins (structure-bound proteins) and cytosol proteins (water-soluble proteins) was investigated in two inbred strains of the mouse, C57BL/6J and DBA/2J. Membrane proteins and cytosol were isolated from the brain and liver of the mouse. The proteins were separated by two-dimensional electrophoresis. A high number of genetic variant proteins (brain, 30; liver, 72) was found in the cytosol. Most of these variants represented changes in the amount of proteins. Electrophoretic mobility changes occurred only in about 1% (brain, 6; liver, 9) of all protein spots of a two-dimensional pattern. In contrast to the cytosol proteins, no genetic variation was detected among the membrane proteins, not even for the quantitative characteristics of the protein spots. The results obtained for the two classes of proteins suggest that the degree of variability in the amount of proteins is related to the degree of variability in the structure of proteins.  相似文献   
95.
A facile chemical synthesis of 1,2-dioleoyl and 1,2-dimyristoyl-sn-glycero-3-phospho-L-serine as well as the synthesis of several deuterated derivatives of phosphatidylserine (2 and 3 positions of serine and in the 3-glycerol position) are described. 360 MHz 1H NMR spectra of phosphatidylserine and the optical activity of various phosphatidylserine diastereomers were measured.  相似文献   
96.
l-(+)-Bornesitol was detected in 23 of 33 genera of Gentianaceae investigated. The only subtribe without l-(+)-bornesitol (3 species tested) was Exacinae. None of the five genera of Menyanthaceae examined were found to contain l-(+)-bornesitol.  相似文献   
97.
Conversion of the inactive form of pyruvate formate-lyase to the catalytically active enzyme is accomplished by the Fe-dependent ‘enzyme II’; reduced flavodoxin, S-adenosyl-L-methionine and the effector pyruvate are required. It was found that adenosylmethionine is reductively processed during activation of pyruvate formate-lyase to yield methionine, adenine and 5-deoxyribose. We suggest that transient adenosylation of enzyme II is required for its function as a converter enzyme.  相似文献   
98.
—The effect of retinal ablation on the high and low affinity uptake of choline, GABA, glutamate, glycine and proline into the crude mitochondrial fraction of the pigeon optic tectum was studied. After 4–8 weeks of degeneration the uptake for glutamate, and to a lesser degree the uptake for GABA, at both the high and the low affinity substrate concentration, decreased. In contrast, the uptake of glycine increased. Kinetic analysis showed that the reduced uptake of glutamate was due to a decrease in the Vmax. By intraocular injection of [3H]proline the retinal endings in the optic tectum were labelled with the fast axoplasmic transport fraction. Optic terminals labelled in this way have the same sedimentation characteristics in continous sucrose gradients as the particles accumulating giutamate in the uptake assay.  相似文献   
99.
Abstract— The distribution of choline acetyltransferase (ChAT) and glutamate decarboxylase (GAD) in different layers of the pigeon optic tectum and in some nuclei of the optic lobe have been investigated. About 40% of GAD and 25% of ChAT were found in the superficial part of tectum, but negligible activity was found in the stratum opticum. The highest GAD activity was found in layers 3-7 (according to the nomenclature of C ajal , 1911) with a peak in layer 4. ChAT activity peaked in layers 3, 5. 8 and 10/11. Its distribution correlated well with the staining pattern of AChE, particularly in the superficial part of the tectum. The distribution of ChAT and GAD did not change significantly 4 weeks after enucleation. ChAT and GAD activities were high in the nucleus isthmi, pars parvocellularis (Ipc). The activity of GAD was also high in the nucleus intercollicularis (ICo), the other nuclei showed less activity of both enzymes.  相似文献   
100.
The cucurbitacins in roots of Bryonia dioica and B. alba have been investigated. Both species contain the cucurbitacins E, B, I, D, J, K and L, the dihydrocucurbitacins E and B, and tetrahydrocucurbitacin I. The detection of certain cucurbitacin aglycones depends upon the date of harvest, the duration of storage and the methods used for extraction.  相似文献   
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