Chlorpromazine and other psychoactive drug induced alterations of a membrane bound enzyme in rat brain

Psychoactive drugs like chlorpromazine (CPZ), imipramine, lithium and amphetamine in one way or another affect behaviour. The drug responses are presumably mediated by inducing a change in the activity of membrane bound enzymes. CPZ is very potent in inhibiting the alkaline phosphatase activity in rat brain. The combined effect of CPZ with other drugs shows that CPZ and imipramine together inhibit the enzyme activity significantly greater than the individual inhibition either by CPZ or by imipramine alone. Effective inhibition of the alkaline phosphatase activity with a single drug or combined drugs may lead to a change in neuronal permeability through glucocorticoids thereby affecting mood.     

Production of a thermophilic,extracellular alkaline protease by Bacillus stearothermophilus AP-4

A thermophilic Bacillus stearothermophilus strain AP-4 excreting a thermostable alkaline protease, was isolated from a local compost. Maximum activity of protease (250 U/ml) was after 36 h growth in broth at pH 9.0 and at 55°C. The protease was optimally active at pH 9.0 and 55°C and was stable in 5 mm CaCl₂. The enzyme was completely inactivated by PMSF, EDTA and -mercaptoethanol. It is therefore a metal ion-dependent, alkaline, serine protease.R. Dhandapani and R. Vijayaragavan are with the Centre for Plant Molecular Biology & Biotechnology, Tamil Nadu Agricultural University, Coimbatore 641 003, India     

Alkaline phosphatase and peptidase activities in Caco-2 cells: Differential response to triiodothyronine

Summary Caco-2 cell human colon adenocarcinoma cell line was used to study the hormonal regulation of small intestinal epithelial cell differentiation. We had previously shown that insulin-transferrin-selenium and triiodothyronine (5 × 10⁻⁸ M)-supplemented medium can best replace serum after 2 days of culture for both the maintenance and differentiation of Caco-2 cells. The present study demonstrates that precoating petri dishes with complete serum allows the growth and differentiation of Caco-2 cells seeded directly in serum-free medium. On the other hand, precoating with dialyzed serum inhibits alkaline phosphatase and dipeptidyl-dipeptidase IV activities by more than 50%. The results obtained with complete serum-precoated culture plates indicate that there is no synergy between insulin and triiodothyronine because cells maintained in transferrin-selenium and triiodothyronine-supplemented medium, with or without insulin, express comparable enzyme activities. Moreover, large increases in alkaline phosphatase and dipeptidyl-dipeptidase IV activities were observed when triiodothyronine was added to the culture medium by the time confluency was reached. In contrast, γ-glutamyltransferase was lowered to a greater extent when triiodothyronine was present from the beginning of culture. These findings show that triiodothyronine preferentially stimulates alkaline phosphatase and dipeptidyl-dipeptidase IV activities during the differentiation period whereas it selectively inhibits γ-glutamyltransferase during the proliferation phase. Triiodothyronine acts in a dose-dependent manner.     

Ontogeny of pituitary cell-types and the hypothalamo-hypophysial relationship during early development of chum salmon,Oncorhynchus keta

Tissue non-specific alkaline phosphatase is a membrane-bound glycoprotein enzyme which is characterized by its phosphohydrolytic, protein phosphatase, and phosphotransferase activities. This enzyme is distributed virtually in all mammalian tissues, particularly during embryonic development. Its expression is stagespecific and can be demonstrated in the developing embryo as early as the 2-cell stage. It has been suggested that tissue non-specific alkaline phosphatase might play a role in tissue formation. In the study reported here, a genetransfer approach was employed to investigate possible roles for this enzyme by inserting the cDNA for rat tissue non-specific alkaline phosphatase into CHO and LLC-PK1 cells. Permanently transfected cell-lines expressing varying levels of alkaline phosphatase were estblished. The data showed that functional enzyme was expressed in the transfected cells. Cell spreading and attachment were enhanced in transfected CHO cells expressing high levels of tissue non-specific alkaline phosphatase but not in the LLC-PK1 cells. Further, in CHO cells, proliferation was shown to be inversely proportional to the level of the tissue non-specific alkaline phosphatase expression. Homotypic cell association was demonstrated in both alkaline phosphatase-positive and alkaline phosphatase-negative cells in both CHO and LLC-PK1 celllines. Taken together, these findings suggest that in addition to a role in mineralization of bone, tissue nonspecific alkaline phosphatase might also play a role in other cell activities, including those related to differentiation, such as cell-cell or cell-substrate interaction and proliferation.     

鼠肝抽提液中磷酸酶活性终止方法的改进

改进了一种分析磷酸酶活性的终止酶反应方法.该方法通过在酶反应进行到一定程度时,在反应混合物中加入酶反应终止液(1mol/L NaOH-0.2mol/L EDTA),从而使测定更简捷、精确.     

Analysis of serine/threonine-linked oligosaccharides derived by alkaline-borohydride treatment of mucin glycoproteins electroblotted onto membranes: comparison of the saccharide profiles of the 390 kDa and 350 kDa forms of epitectin

Alkaline borohydride treatment is widely used for the release of carbohydrate moieties from O-glycosylated glycoproteins and mucins. We have adapted this procedure to micro quantities of glycoproteins blotted on membranes. After electrophoresis and transfer to nitrocellulose, nylon or polyvinylidene difluoride membrane, alkaline borohydride treatment was done directly on glycoprotein containing areas of membrane which were cut out with the aid of guide strips stained with Coomassie Blue or lectin-digoxigenin. In combination with standard saccharide fractionation techniques, this procedure can be used to characterize the oligosaccharides of mucins or mucin-type glycoproteins that are separated by gel electrophoresis from crude sources. Using this approach we have characterized the saccharides derived from the two species of epitectin, a malignancy-associated mucin type glycoprotein, isolated from metabolically labelled H.Ep2 cells.     

Superoxide dismutase activity of the captopril-iron complex

With an assay that generates superoxide anion radicals without the intervention of metal ions we investigated the antioxidant properties of captopril, an angiotensin-converting enzyme inhibitor with a sulfhydryl group. Under these conditions, increasing concentrations of the drug were seen not to scavenge O· ₂ ^– directly. However, a combination of captopril and iron could bring about the breakdown of the superoxide anion; a result that may help to understand the free radical-scavenging properties of captopril.     

Kinetic analyses of the membrane-bound alkaline phosphatase activity of hymenolepis diminuta (Cestoda: Cyclophyllidea) in relation to development of the tapeworm in the definitive host

The specific activities of the alkaline phosphatase (APase), type I phosphodiesterase and 5'-nucleotidase activities associated with the brush-border plasma membrane of the tapeworm, Hymenolepis diminuta, decrease significantly as the tapeworm grows and matures. Kinetic analyses of the APase activity associated with membrane preparations from whole 6-, 12-, and 18-d-old H diminuta, and individual pieces of 18-d-old H diminuta cut into ten pieces of equal length, failed to demonstrate qualitative changes in the APase activity. Therefore, the decreased specific activities are apparently due to changes in the ratios of enzymatically active to enzymatically inactive membrane proteins (ie, quantitative changes in the membrane proteins) which occur as the tapeworm grows.     

Biochemical changes during germination and seedling growth in Cuscuta campestris

Changes in the contents of starch, protein, DNA, RNA, total phosphorus, acid soluble phosphorus and inorganic phosphorus, and in the activities of some enzymes of carbohydrate, amino acid, nucleic acid and phosphate metabolism were studied during the germination of Cuscuta campestris seeds. The results are expressed on per seed basis.
Starch content in Cuscuta seeds showed a steady decline with most of it depleted by the end of the eighth day of germination. Protein content increased with germination up to 48 h and then decreased. RNA and DNA contents increased to a maximal level on the fourth day of germination and then decreased. Total phosphorus in the seeds remained almost unchanged during the period of study. Both trichloroacetic acid soluble and inorganic phosphorus increased until the third day and then decreased. Phytin was rapidly hydrolyzed with little being detectable by the seventh day of germination. Glucose-6-phosphate dehydrogenase increased with germination, while fructose bisphosphate aldolase which is indispensable for glycolysis, decreased with germination. Ribonuclease and deoxyribonuclease increased till the third and fourth day, respectively, and then decreased. Aspartate and alanine aminotransferases showed a maximum on the second day and then decreased. Activities of alkaline fructose-1,6-bisphosphatase and phytase were absent in the dry seeds and appeared only on the second day of germination. Both α- and β-amylase activities were present in the dry seed.