Homology of L-gulonolactone oxidase of species belonging to Mammalia,Aves, and Amphibia

Summary Immunological cross-reactivity of L-gulonolactone oxidase of different species (rat, chicken, and bullfrog) was tested by the Ouchterlony technique. Antiserum directed against the enzyme from chicken kidney reacted with rat liver enzyme as well as with bullfrog kidney enzyme. This finding suggests that there is, at least partly, sequence homology among the enzymes from species belonging to the three classes, Mammalia, Aves, and Amphibia.     

A comparative study of the innervation of the choroid plexus in amphibia

The aminergic and cholinergic innervation of choroid plexuses in three species of amphibia was investigated. Plexuses of the Japanese toad and the bullfrog had poor innervation by adrenergic nerves of sympathetic origin, but in the clawed toad, these plexuses were heavily innervated by adrenergic axons from ganglion cells located in the plexus stroma. Nerve fibers positive for acetylcholinesterase were not found in the plexuses, except for a few fibers with very weak enzyme activity in the clawed toad.     

A comparative study of the innervation of the choroid plexus in amphibia

Summary The aminergic and cholinergic innervation of choroid plexuses in three species of amphibia was investigated. Plexuses of the Japanese toad and the bullfrog had poor innervation by adrenergic nerves of sympathetic origin, but in the clawed toad, these plexuses were heavily innervated by adrenergic axons from ganglion cells located in the plexus stroma. Nerve fibers positive for acetylcholinesterase were not found in the plexuses, except for a few fibers with very weak enzyme activity in the clawed toad.Acknowledgment. The authors are very grateful to Prof. T. Wasano (Professor emeritus of Kyushu University) for his encouragement and advice during the course of the present work.     

Purification and properties of ornithine aminotransferase from rat brain

Ornithine aminotransferase (E.C. 2.6.1.13) from rat brain was purified 100-fold by ammonium sulphate fractionation, DEAE cellulose chromatography, calcium phosphate gel and alumina C gamma gel. Pyridoxal phosphate was essential for maximum activity of the enzyme. The brain enzyme did not differ from liver and kidney enzymes in properties such as pH optimum, Km, substrate specificity and the inhibition by branched chain amino acids. Unlike rat liver enzyme, brain ornithine aminotransferase was able to catalyze the reaction between L-lysine and 2-oxoglutarate. Spermidine and spermine inhibited brain ornithine aminotransferase activity.     

Thyroid hormones and cathepsin D activity in the rat liver,kidney and brain

Summary The effect of thyroidectomy and subsequent treatment with tri-iodothyronine (T₃), as well as that of thyrotoxicosis, was examined on cathepsin D activity in the rat liver, kidney and brain. Thyrotoxicosis resulted in a generalized increase in the enzyme activity in the 3 tissues; the effect of other thyroidal states was diverse and tissue-specific.     

Ratio between large and small carboxy-terminal molecular forms of cholecystokinin in brains of different species

The ratio between large and small carboxy-terminal forms of cholecystokinin in brain extracts from man, pig, dog, rat, chicken, frog and trout was determined by two sequence-specific radioimmunoassays. It was found that the relative amounts of large forms of cholecystokinin; are higher in mammalian brain than in brains of lower species.     

Chronic hydrogen peroxide intake and peroxide metabolizing enzyme activities in some tissues of mice and rats

Chronic daily intake of 0.5% H2O2 in drinking water decreased Se-dependent glutathione peroxidase (Se-GSHPx) activity in rat skeletal muscle, kidney and liver. Non-Se GSHPx activity decreased in kidney. Deprivation of drinking water decreased Se-GSHPx activity in kidney and non-Se GSHPx activity in kidney and liver. H2O2 intake decreased activity of catalase in rat skeletal muscle. H2O2 intake or water deprivation caused no changes in these enzyme activities in mice.     

Tissue-specific induction of intestinal glutathione S-transferases by alpha beta-unsaturated carbonyl compounds

Glutathione S-transferase activity in rat intestinal mucosa was increased by the injection of alpha beta-unsaturated carbonyl compounds such as phorone and diethylmaleate, but that in the liver and kidney was not. Since the administration of cycloheximide completely blocked the increase of the enzyme activity by phorone, the increase of the activity may be due to de novo synthesis rather than enzyme activation.     

Comparison of lysine and tryptophan catabolizing enzymes in rat and bovine tissues

Earlier studies indicate that alpha-aminoadipate aminotransferase (AadAT) and kynurenine aminotransferase (KAT) activities from rat tissues are associated with a single protein. However, our recent studies indicate that AadAT activity from bovine liver and kidney is not associated with KAT activity. To test whether the lysine and tryptophan catabolism in bovine tissues differ from that in rat tissues, we compared the activities of enzymes involved in lysine and tryptophan pathways in rat and bovine tissues. The activities of lysine catabolizing enzymes such as AadAT, lysine alpha-ketoglutarate reductase and saccharopine dehydrogenase in the bovine tissues were significantly lower than those found in rat tissues. The activities of tryptophan catabolizing enzymes such as KAT and kynurenine hydroxylase in the bovine tissues were negligible as compared to those in rat tissues. The results suggest that lysine is degraded via the saccharopine pathway in the livers and kidneys of both species but the metabolism of tryptophan in bovine tissues may be different from that in rat tissues.     

Chronic hydrogen peroxide intake and peroxide metabolizing enzyme activities in some tissues of mice and rats

Summary Chronic daily intake of 0.5% H₂O₂ in drinking water decreased Se-dependent glutathione peroxidase (Se-GSHPx) activity in rat skeletal muscle, kidney and liver. Non-Se GSHPx activity decreased in kidney. Deprivation of drinking water decreased Se-GSHPx activity in kidney and non-Se GSHPx activity in kidney and liver. H₂O₂ intake decreased activity of catalase in rat skeletal muscle. H₂O₂ intake or water deprivation caused no changes in these enzyme activities in mice.     

FSH receptor binding inhibiting activity associated with low molecular weight inhibin from sheep,human, rat and chicken

Summary Low molecular weight inhibin (1500 daltons) was obtained from sheep, human, rat and chicken testes by sequential chromatography on Sephadex G-100 and G-25. In addition to its ability to suppress circulating FSH levels in adult castrated male rats, it also exhibits binding inhibition of I¹²⁵hFSH to rat testicular receptors.     

Insoluble zinc-precipitated phosphomonoesterase from rat kidney

Summary The insoluble form of phosphomonoesterase precipitated by means of Zn²⁺-ions was prepared from the partially purified extract of rat kidney. The freeze-dried preparation of the precipitated enzyme is highly active and is stable on heating at 100°C.     

Immunochemical identity of dipeptidyl aminopeptidase IV from pig serum, liver, submaxillary gland and kidney.

The enzymes which were extracted by autodigestion from the microsomal fractions of the pig kidney, liver and submaxillary gland and from the serum showed an immunochemical identity by a double immunodiffusion test. But the kidney enzyme had a different pI-value from the pI-values of the enzymes of other organs.     

Distribution of contractile proteins and adrenergic nerves in the adrenal gland of guinea-pig, rat and ox as revealed by immunofluorescence and the glyoxylic acid technique.

Myosin and actin were localized in the adrenal gland, using antibodies against these proteins which were isolated from chicken gizzard. Myosin and actin were preferentially located in vascular walls including endothelial cells and in the capsule. In rat and guinea-pig adrenal cortex, the amount of contractile elements in vascular walls corresponded well to the density of adrenergic nerves as revealed with the glyoxylic acid method.     

Distribution of contractile proteins and adrenergic nerves in the adrenal gland of guinea-pig,rat and ox as revealed by immunofluorescence and the glyoxylic acid technique

Summary Myosin and actin were localized in the adrenal gland, using antibodies against these proteins which were isolated from chicken gizzard. Myosin and actin were preferentially located in vascular walls including endothelial cells and in the capsule. In rat and guinea-pig adrenal cortex, the amount of contractile elements in vascular walls corresponded well to the density of adrenergic nerves as revealed with the glyoxylic acid method.Supported by grants from Deutsche Forschungsgemeinschaft.     

Purification and properties of ornithine aminotransferase from rat brain

Summary Ornithine aminotransferase (E.C. 2.6.1.13) from rat brain was purified 100-fold by ammonium sulphate fractionation, DEAE cellulose chromatography, calcium phosphate gel and alumina C gel. Pyridoxal phosphate was essential for maximum activity of the enzyme. The brain enzyme did not differ from liver and kidney enzymes in properties such as pH optimum, K_m, substrate specificity and the inhibition by branched chain amino acids. Unlike rat liver enzyme, brain ornithine aminotransferase was able to catalyze the reaction between L-lysine and 2-oxoglutarate. Spermidine and spermine inhibited brain ornithine aminotransferase activity.Acknowledgments. D.R.D. is thankful to U.G.C., India, for the award of a fellowship under the special assistance programme. Present address: Department of Pediatrics and Communicable Diseases, F2815, Box 066, C.S. Mott Children's Hospital, University of Michigan, Ann Arbor, MI 48109, USA.     

Comparison of lysine and tryptophan catabolizing enzymes in rat and bovine tissues

Summary Earlier studies indicate that -aminoadipate aminotransferase (AadAT) and kynurenine aminotransferase (KAT) activities from rat tissues are associated with a single protein. However, our recent studies indicate that AadAT activity from bovine liver and kidney is not associated with KAT activity. To test whether the lysine and tryptophan catabolism in bovine tissues differ from that in rat tissues, we compared the activities of enzymes involved in lysine and tryptophan pathways in rat and bovine tissues. The activities of lysine catabolizing enzymes such as AadAT, lysine -ketoglutarate reductase and saccharopine dehydrogenase in the bovine tissues were significantly lower than those found in rat tissues. The activities of tryptophan catabolizing enzymes such as KAT and kynurenine hydroxylase in the bovine tissues were negligible as compared to those in rat tissues. The results suggest that lysine is degraded via the saccharopine pathway in the livers and kidneys of both species but the metabolism of tryptophan in bovine tissues may be different from that in rat tissues.Acknowledgments. This work was supported by a grant from the Children's Hospital of Michigan and by a Research Career Development Award from the National Institutes of Health to D. R. Deshmukh.     

Inhibition of rat liver transglutaminase by nucleotides

Summary Tissue-type transglutaminase (TGase) was purified from rat liver, and the effects of nucleotides on its activity were examined. The enzyme activity is inhibited by ATP in a concentration-dependent way, with complete inhibition by 3 mM ATP. Partially-purified TGase from human brain was inhibited by ATP in a manner similar to that observed with the rat liver enzyme. This suggests that the inhibition is a common phenomenon for tissue-type TGase in all species and tissues. The inhibition is reversible since full activity is restored by lowering the ATP concentration. CTP has a TGase-inhibitory potency equivalent to that of ATP, whereas GTP and UTP possess about 50% of the inhibitory activity of ATP. ADP inhibits TGase activity to the same extent as ATP, but AMP causes much less inhibition, and there is no inhibition by adenosine or adenine. The inhibition by ATP is insensitive to ionic strength and is non-competitive with the substrate putrescine. Since ATP levels in cells are of mM order, these results suggest that TGase activity is controlled by ATP in vivo.     

Inhibition of rat liver transglutaminase by nucleotides.

Tissue-type transglutaminase (TGase) was purified from rat liver, and the effects of nucleotides on its activity were examined. The enzyme activity is inhibited by ATP in a concentration-dependent way, with complete inhibition by 3 mM ATP. Partially-purified TGase from human brain was inhibited by ATP in a manner similar to that observed with the rat liver enzyme. This suggests that the inhibition is a common phenomenon for tissue-type TGase in all species and tissues. The inhibition is reversible since full activity is restored by lowering the ATP concentration. CTP has a TGase-inhibitory potency equivalent to that of ATP, whereas GTP and UTP possess about 50% of the inhibitory activity of ATP. ADP inhibits TGase activity to the same extent as ATP, but AMP causes much less inhibition, and there is no inhibition by adenosine or adenine. The inhibition by ATP is insensitive to ionic strength and is non-competitive with the substrate putrescine. Since ATP levels in cells are of mM order, these results suggest that TGase activity is controlled by ATP in vivo.     

Molecular cloning and analysis of the protein modules of aggrecans

The large aggregating chondroitin sulfate proteoglycan of cartilage, aggrecan, has served as a prototype of proteoglycan structure. Molecular cloning has elucidated its primary structure and revealed both known and unknown domains. To date the complete structures of chicken, rat and human aggrecans have been deduced, while partial sequences have been reported for bovine aggrecan. A related proteoglycan, human versican, has also been cloned and sequenced. Both aggrecan and versican have two lectin domains, one at the amino-terminus which binds hyaluronic acid and one at the carboxyl-terminus whose physiological ligand is unknown. Both lectins have homologous counterparts in other types of proteins. Within the aggrecans the keratan sulfate domain may be variably present and also has a prominent repeat in some species. The chondroitin sulfate domain has three distinct regions which vary in their prominence in different species. The complex molecular structure of aggrecans is consistent with the concept of exon shuffling and aggrecans serve as suitable prototypes for comprehending the evolution of multi-domain proteins.