Taurine and other free amino acids in the retina, vitreous, lens, iris-ciliary body, and cornea of the rat eye.

Levels of free amino acids were determined quantitatively in whole ocular tissues of the rat eye with aid of a sensitive amino acid analyzer. The tissues studied were the retina, vitreous, lens, iris-ciliary body, and cornea. The retina and lens contained a more concentrated free amino acid pool than other tissues. The neuroactive amino acids taurine. GABA, glutamic acid, aspartic acid, and glycine were clearly enriched in the retina. Taurine was the most abundant amino acid in all five tissues studied, and its high concentration in non-neural tissues, especially the lens, suggests that it must have other functions as well as neurotransmitter ones in the rat eye.

Comparison of different myelin isolation methods by use of nonequilibrium pH gradient gel electrophoresis.

Myelin was isolated from bovine white matter by five published procedures and several modifications of two of them. Comparison of the protein profiles of the preparations by nonequilibrium pH gradient gel electrophoresis, revealed clear differences in myelin protein content and composition between preparations obtained by different methods. In isolation methods where the medium contained salts, some of the myelin proteins were solubilized, the phenomenon being most pronounced in long-period isolations in buffered CsCl solution.

Macromolecular relationships of liver nuclei and amino acid composition of total histones during bovine ontogeny.

The weight of the liver and the macromolecular composition of the liver and its nuclei during bovine ontogeny were compared. The findings suggest that bovine liver growth proceeds in three phases. The macromolecular composition of the liver nuclei was found to remain fairly constant throughout bovine ontogeny.

Resolution and purification of taurine- and GABA-synthesizing decarboxylases from calf brain.

The present work describes a procedure for the co-purification of cysteine sulfinate decarboxylase (CSAD) and glutamate decarboxylase (GAD) from calf brain. A crude enzyme preparation was first made from brain homogenate by acid precipitation and ammonium sulphate fractionation. Subsequent fractionation of the decarboxylase preparation by cation exchange chromatography on CM-Sepharose CL-6B revealed the existence of a specific CSAD enzyme, which has no GAD activity. The GAD activity peak was found to possess CSAD activity. Further fractionation by gel filtration on Sephacryl S-200 separated the specific CSAD activity into two enzyme forms, one of them having a molecular weight of 150,000 and the other of 71,000. GAD activity was eluted from the gel filtration column in a single peak (mol wt 330,000) and showed CSAD activity. The purification of the specific CSAD enzyme was 920-fold and that of GAD activity 850-fold as compared with the starting material, whole calf brain. SDS gel electrophoresis indicated that the purified CSAD and GAD enzymes consisted of two or more subunits. The crude decarboxylase preparation was analysed by isoelectric focusing in ultra-thin polyacrylamide gel in the pH range 3.5-10.0. The most active fraction of CSAD indicated an isoelectric point of 6.5 and that of GAD 6.8. The pH optimum for CSAD activity in the crude preparation was 7.2 and that for GAD activity 7.9.

Developmental changes in mouse brain polyamine metabolism.

Mouse brain ornithine decarboxylase (ODC) activity is high at the time of birth, whereas S-adenosyl-L-methionine decarboxylase (SAM-DC) activity is low. ODC activity, and putrescine, spermidine and spermine concentrations decline rapidly during postnatal development to the low level characteristic of mature brains, while SAM-DC activity behaves in the opposite manner. The fluctuations in mouse brain polyamine metabolism are in accord with those found in the rat. The apparent Km values of ODC and SAM-DC for their substrates decline parallel with the decrease of substrate and product concentrations during ontogeny suggesting substrate and/or product dependent regulation of polyamine synthesis in the developing brain.

Isoelectric focusing of myelin membrane proteins.

Human myelin was isolated from the white matter of autopsy brains. Myelin proteins were characterized by isoelectric focusing in ultrathin slab gels in a pH range from 3.5 to 10 after solubilization with urea and Nonidet P 40. The protein profile in the acidic region (pH below 6.2) revealed at least twelve faint bands which comprised only a few percent of the total myelin proteins. Most of the myelin proteins were focused in the neutral range (pH 6.2-7.8) which showed two sharper and three broader major bands, the total number of bands in this region being about twenty. The basic pH range (pH above 7.8) contained about 30% of the proteins, and revealed a very intense band near the cathode with seven to nine weaker bands below pH 9.0. When the myelin was partially delipidated prior to solubilization, an additional broad "band" was observed at the area pH 8.0-8.5.

On the metabolism of ornithine in synaptosomal preparations.

The present results show that ornithine is metabolized to glutamate by isolated synaptosomes from mouse cerebral cortex. Under the experimental conditions used the glutamate was channelled further to the tricarboxylic acid cycle, and to a lesser degree to GABA. The possible significance of these metabolic pathways are discussed. Results of an earlier study suggest an excessive metabolism of ornithine via putrescine to GABA in synaptosomes. Those results could not be verified in the present study and a possible reason for the disagreement is demonstrated. However, the present results suggest that putrescine, which is known to be produced from ornithine elsewhere in the nervous tissue, may be metabolized to GABA in synaptosomes.

Characterization of cerebral cysteine sulfinic acid decarboxylase. Molecular parameters and inhibition studies.

The molecular properties of cysteine sulfinic acid decarboxylase (EC 4.1.1.29) from calf brain were examined in a crude enzyme preparation. The Stokes radius (42 A) was determined by gel filtration and the sedimentation coefficient, s20,w (6.1 x 10(-13 s) by density gradient centrifugation. Calculation of the molecular weight and frictional ratio gave values of 73,000 and 1.52, respectively. beta-Mercaptopropionic acid and an arginine reagent, phenylglyoxal, were observed to be potent inhibitors of the enzyme. Pyridoxal phosphate, a cofactor of the decarboxylase, was observed to protect the enzyme against phenylglyoxal inhibition. This result indicates that an arginine residue may be located at the active site of cysteine sulfinic acid decarboxylase. The components of taurine metabolism gave little or no inhibition of the decarboxylase. Glutaric acid, malic acid and C-allylglycine, all widely known as potent inhibitors of glutamic acid decarboxylase, only slightly inhibited cysteine sulfinic acid decarboxylase.

Diurnal levels of polyamines and activities of ornithine and S-adenosyl-L-methionine decarboxylases in mouse brain.

The levels of putrescine and spermine in mouse brain were rather constant at different times of day, as were the activities of ornithine and S-adenosyl-L-methionine decarboxylases. Contrary to an earlier report, the level of spermidine was found to be relatively constant. A possibly significant feature in the present results was the steady decline during the light period and rise during darkness of cerebral spermidine and spermine levels, the differences between maximum and minimum being about 15% for both compounds.

Partial purification of cysteine sulfinic acid decarboxylase from calf brain.

Cysteine sulfinic acid decarboxylase (EC 4.1.1.29) was purified from calf brain by pH precipitation, ammonium sulfate fractionation, gel filtration and DEAE-Sephadex A-50 chromatography. The enzyme preparation decarboxylated both cysteine sulfinic acid and cysteic acid at all steps of the purification and the ratio of the velocity of decarboxylation of cysteine sulfinic acid to that of cysteic acid was constant, about 2, throughout the purification procedure. The pH optimum was 7.2 both for cysteine sulfinic acid and cysteic acid. The molecular weight of the enzyme was estimated at 65 000 using gel filtration on a Sephadex G-200 column. Its Km's were 0.9 mM for cysteine sulfinic acid and 1.6 mM for cysteic acid, with Vmax values of 60.5 and 33.5 nmol/h(mg protein), respectively.

[The radioprotective effect of iodine and its preventive action on renal calcification (author's transl)]. / Der Strahlenschutzeffekt des Jods und seine kalzifikationsverhindernde Wirkung auf die Nieren.

The protective effect of iodine against injurious damage caused by ionizing radiation was studied in 26 rats irradiated with cobalt-60 gamma rays as a single dose of 1000 rads (10 joule/kg). Twelve rats were pretreated 13 times every second day before irradiation. After irradiation they were treated daily during 21 days with 2.5 to 3.0 mg iodine given subcutaneously along with 9 mg Ca2+ (as gluconolactobionate) intramuscularly. In addition, they received 500 micrograms of iodine in their food daily. 67% of the iodine-treated rats remained alive after 30 days in contrast to 36% of the control rats which received Ca2+ only. 10 further rats which received neither iodine nor Ca2+ died within 3 to 5 days after irradiation. Deposition of calcium in the renal parenchyma was observed in 12 out of the 14 control rats, but only in 2 out of the 12 iodine-treated rats. It can be concluded from the results that iodine has a protective effect on ionizing radiation. It is assumed that iodine promotes the energy-conserving mechanism in mitochondria and also prevents the irradiation-induced decrease in calcium efflux.

Stimulation of L-ornithine and S-adenosyl-L-methionine decarboxylases by beta-(p-chlorophenyl)-gamma-aminobutyric acid in mouse tissues.

Injections of beta-(p--chlorophenyl)-gamma-aminobutyric acid caused a monophasic stimulation of the activity of neural L-ornithine decarboxylase, to reach a maximum of 9-fold compared with the control values 3 h after treatment. Stimulation of hepatic L-ornithine decarboxylase was biphasic, the activity reaching its first peak, 48-fold compared with the control values, similarly at about 3 h after administration, and returning to its initial level by 4 h, and rising to a second peak, about one-third of the magnitude of the first, about 25 h after the injection. The effect in the adrenal gland of the mouse was multiphasic, reaching its maximum, 94-fold enzyme activity compared with the control values, 7--8 h after treatment. There were also marked fluctuations in the activity of S-adenosyl-L-methionine decarboxylase in the tissues examined.