Journal of Neurochemistry

Schwartz, J. C.; Lampart, C.; Rose, C.

doi: 10.1111/j.1471-4159.1970.tb03722.xpmid: 5474655

—Properties of the histamine‐forming enzyme in rat brain were studied, utilizing a sensitive fluorometric assay. The optimum pH was related to substrate concentration and found to be6·4 at 10−2m‐histidine; the apparent Km was about 4·10−4m; enzyme activity was inhibited by α‐hydrazino ‐histidine and brocresine but was not affected by α‐methyl DOPA or benzene. These different data suggest that the 'specific’histidine decarboxylase (EC 4.1.1.22)—and not the aromatic l‐aminoacid decarboxylase—is involved. Determination of enzyme activity and histamine level in different areas of the rat brain revealed important regional differences, the two values being roughly parallel.

Langley, O. K.

doi: 10.1111/j.1471-4159.1970.tb03723.xpmid: 4097507

—A study of the staining characteristics of Alcian blue in mammalian peripheral myelinated nerve in the presence of added electrolyte has enabled a comparison to be made of polyanions, formerly shown to be present at nodes of Ranvier, with other chemically defined macromolecules present in the same tissue. Two types of polyanion were shown to exist at nodes, one probably carboxylated and the other containing in addition sulphate ester groups. The possible physiological functions of such materials are discussed in relation to the role played by the nodes of Ranvier in conduction of the nerve impulse.

Cooper, Mary F.; Webster, G. R.

doi: 10.1111/j.1471-4159.1970.tb03724.xpmid: 5474656

—Lipid‐free extracts of rat and human brain have been prepared and shown to contain phospholipase A1 and A2 activities and a lysophospholipase. The phospholipase Aj activity has pH optima of 4·2 and 4·6 in rat and human brain, respectively; it can be partially purified and isolated in high yields by dialysing the extracts at low pH. The purified preparations hydrolyse the ester bond at the 1‐position in lecithin, phosphatidyl‐ethanolamine and phosphatidylserine, but have little or no action on triglyceride or cholesterol ester. An assay system for the enzyme is described. Phospholipase A2 activity is optimal at pH 5·5 in rat brain extracts and at pH 5·0 in extracts of human brain. The phospholipase A2 activity of human cerebral cortex is largely unaffected by heating extracts at 70°C for 5 min, whereas this treatment substantially inactivates phospholipase A1 and completely destroys lysophospholipase. Phospholipase A1 is widely distributed in both grey and white matter of human brain and is also present in peripheral nerve. Phospholipase A2 activity is lower than A1 in all regions of the CNS examined so far, and is absent from peripheral nerve. Neither enzyme appears to require Ca2+ but both are inhibited by di‐isopropylfluorophosphate (DFP, 2 × 10−6 m) and thus differ from phospholipase A of pancreas. These studies confirm that the phospholipase A1 and A2 activities in brain are due to separate enzymes.

Burdman, J. A.

doi: 10.1111/j.1471-4159.1970.tb03725.xpmid: 5474657

Purified neuronal and glial nuclei were separated from rat brain cells. The fraction rich in neuronal nuclei contained 68 ± 9 per cent neuronal nuclei and the fraction rich in glial nuclei contained 89 ± 6 per cent glial nuclei. The fraction rich in neuronal nuclei isolated from cells of adult rat brain incorporated l‐(4,5‐3H)leucine into TCA‐insoluble material at a rate comparable to those of the microsomal and the soluble fractions of the brain, and at a much higher rate than the fraction rich in glial nuclei. The proteins soluble in buffered‐saline, the acid‐soluble deoxyribonucleoproteins, and the residual proteins of the neuronal nuclei are apparently the proteins which account for the higher specific activity of neuronal proteins compared with glial nuclear proteins. In liver and kidney, the incorporation of (3H)leucine into nuclear proteins was lower than into other subcellular fractions from the same organs.

Sjöstrand, J.; Frizell, M.; Hasselgren, P.‐O.

doi: 10.1111/j.1471-4159.1970.tb03726.xpmid: 4097508

—Colchicine injected intracisternally markedly inhibited the rapid migration (300‐400 mm/day) of labelled proteins in the hypoglossal and vagus nerve of the rabbit. The transport of acetylcholinesterase (EC 3.1.1.7) and choline acetyltransferase (EC 2.3.1.6) previously shown to move with the slow (5‐26 mm/day) phase of axoplasmic transport in these nerves, was only partially blocked. In view of this differential effect on axonal flow, we suggest that the neurotubules, on which colchicine acts preferentially, are primarily involved in the rapid (300‐400 mm/day) axoplasmic flow. After local injection of colchicine into the nerves both the rapidly migrating labelled proteins and the enzymes (AChE and ChAc) accumulated above the site of injection to the same degree as they accumulate above a nerve ligation. Since this blockage of enzyme transport occurred after concentrations of colchicine much higher than those used for intracisternal injections these findings after local injection may represent more severe effects on axonal transport systems.

Watanabe, S.; Oisuki, S.; Mitsunobu, K.; Sannomiya, T.; Okumura, N.

doi: 10.1111/j.1471-4159.1970.tb03727.xpmid: 5474658

—In order to study changes of the glycolytic‐respiratory system and amino acid metabolism associated with blood flow disturbance, the cat brain perfusion was conducted with artificial blood containing (U‐14C)glucose and the results were compared with those of standard perfusion keeping the cerebral blood flow at constant rate. The findings of the present study are briefly summarized: (1) In blood flow disturbance there was observed an accumulation of lactate just as seen in the low functional state observable in the standard perfusion. However the increase in relative specific activity of lactate was not so marked as the rise in cerebral lactate content, and this indicates that there is an increase of lactate production from substrates other than glucose as well as an increase of net flow of glucose carbon to lactate. (2) In blood flow disturbance relative specific activities of glutamate, aspartate, glutamine and respiratory CO2 were decreased as compared with those in the brain of high functional state. The relative specific activity of GABA in the reduced blood flow brain was at the same level as that of the brain at high functional state and it was higher than the relative specific activity of glutamate. (3) The relative specific activity and content of alanine were increased in the low function brain with standard perfusion.

White, H. L.; Cavallito, C. J.

doi: 10.1111/j.1471-4159.1970.tb03728.xpmid: 5474659

—Choline acetyltransferase was extracted from Lactobacillus plantarum by relatively gentle procedures involving penicillin treatment, osmotic shock and passage through a French pressure cell. After partial purification, the extract was compared with choline acetyltransferase of calf caudate nucleus for kinetic properties and response to a class of inhibitors which consists of analogues of styrylpyridine. Both enzymes obeyed a sequential mechanism with Michaelis constants for the bacterial enzyme, Km= 8 μm vs. acetyl‐CoA and 0·44 mm vs. choline; and for the caudate nucleus enzyme, Km= 15 μm vs. acetyl‐CoA and 0·8 mm vs. choline. Both were stabilized by dithiothreitol and EDTA. The extracts differed in that the bacterial enzyme was more labile and apparently was susceptible to conformational changes, which modified its response to the styrylpyridinetype inhibitors. The use of intact cells of Lactobacillus plantarum as an in vivo system for studying the inhibition of choline acetyltransferase by styrylpyridines was possible only for non‐quaternary analogues, which exist as an equilibrium mixture of charged and uncharged species.

SVENNEBY, G.

doi: 10.1111/j.1471-4159.1970.tb03729.xpmid: 5474660

—Pig brain glutaminase (EC 3.5.1.2 L‐glutamine amidohydrolase) has been purified about 5000‐fold from acetone powder. Glutaminase exists in different molecular forms, dependent on the ionic composition of the buffer. The three main forms are similar to those of kidney glutaminase and therefore called the tris‐HCl enzyme, the phosphate enzyme, and the phosphate‐borate enzyme. The sedimentation coefficients, as estimated by sucrose gradient technique, are 7·3, 8·7, and 53, respectively. Glutaminase has a pH optimum of about 9, but the pH curves of the tris‐HCl enzyme and the phosphate‐borate enzyme have different shapes. The apparent pK1 of the tris‐HCl enzyme‐substrate complex is similar to pK2 of inorganic phosphate, the apparent pK2 of both the tris‐HCl and the phosphateborate enzyme complexes is similar to pK2 of glutamine. By use of the electron microscope we were able to see the phosphate‐borate enzyme.

De Iraldi, Amanda Pellegrino; Rodríguez, Georgina; Arnaiz, De Lores

doi: 10.1111/j.1471-4159.1970.tb03730.xpmid: 5474661

—The activity of thiamine pyrophosphatase was determined in segments and segment subfractions from normal and crushed sciatic nerves of the cat. Activity of the enzyme was increased in segments near the site of compression. The highest activity of the enzyme was in a fraction rich in tubular and vesicular elements resembling those observed in intact compressed nerves. On morphological grounds these structures have been interpreted as originating from Golgi‐like structures.

Sims, K. L.; Pitts, F. N.

doi: 10.1111/j.1471-4159.1970.tb03731.xpmid: 5474662