The secretory nature of the excretory gland cells of Strephanurus dentatus. 3. Proteinase inhibitors

A proteinase inhibitor(s) was found in extracts of the excretory gland cells, intestines, esophagi, reproductive organs, and body walls from Stephanurus dentatus adults. The specific activity of the inhibitor(s) in the excretory gland cell extract was 45–175 times greater than in the other tissues. It is heat stable at pH 5.0 and inhibits the esterolytic activity of trypsin and chymotrypsin using p-toluenesulfonyl-l-arginine methyl ester hydrochloride (TAME) and benzoyl-l-tyrosine ethyl ester (BTEE) as the substrates, respectively, and also the proteolytic activity of both chymotrypsin and trypsin using casein as the substrate. S. dentatus adults maintained in NCTC 109 medium, secreted a trypsin inhibitor.     

Aspartate carbamoyltransferase from rat liver

1. Aspartate-carbamoyltransferase activity was concentrated from rat-liver preparations. Only l-aspartate, beta-benzyl-l-aspartate and beta-erythro-hydroxy-dl-aspartate were carbamoylated enzymically. The K(m) for l-aspartate and carbamoyl phosphate have been determined by three methods: colorimetric procedure, radioactive assay with [(14)C]aspartate and an assay with [(14)C]carbamoyl phosphate. 2. The K(m) for aspartate has been determined as a function of the pH; the pK of the functional group at the active site of the enzyme, pK(e), was at pH9.0. Enzymic activity was diminished in the presence of N-ethylmaleimide, p-hydroxymercuribenzoate and the heavy metals Ag(+), Hg(2+), or Zn(2+). The inhibitions could be prevented by mercaptoethanol. These findings suggested the association of a thiol group with the enzymic activity. 3. Enzymic activity was also decreased by sodium lauryl sulphate, urea and dioxan. Competitive inhibition (with l-aspartate) was manifested by maleate, succinate, oxaloacetate, beta-erythro-hydroxy-dl-aspartate and beta-benzyl-l-aspartate. The K(i) for most of these inhibitions has been determined. 4. The properties of the liver enzyme are compared with those of Escherichia coli aspartate carbamoyltransferase and the implications of the findings are discussed.     

Some factors stimulating and inhibiting pancreatic deoxyribonuclease

Для выяснения роли ДН-азы в реакции трансформации исследовали действие различных сред, применяемых при трансформации пневмококков, на активность панкреатической ДН-азы. Эти виды среды резко повышали активность фермента. Далее, было установлено, что это повышение вызывается yeast-экстрактом, входящим в состав этих сред. С помщяю спектрального анализа и пламенного спектрофотометра в yeast-экстракте были обнаружены Mg²⁺, Ca²⁺, K⁺ и Na⁺. Изучалось действие этих ионов на активность ДН-азы и было установлено, что в присутствии Mg²⁺ (5×10^?3 m)иCa²⁺(вконцентрации 2×10^?4 m) резко повышается активность фермента, тогда как прибавление к этой системе KCl в концентрации 2×10^?1, 2×10^?2, 2×10^?3 и 2×10^?4 m оказывает угнетающее действие.—Обсуждается возможное влияние этих ионов на peaкцию трансформации.     

Plant-Derived Neurotoxic Amino Acids (β-N-Oxalylamino-l-Alanine and β-N-Methylamino-l-Alanine): Effects on Central Monoamine Neurons

In the present study the subacute effects of beta-N-oxalylamino-L-alanine (BOAA) and beta-N-methylamino-L-alanine (BMAA) on CNS monoamine neurons in rats were investigated following intracisternal injections or local intracerebral administration into substantia nigra. In vitro effects of BOAA and BMAA on high-affinity synaptosomal uptake of dopamine (DA), noradrenaline (NA), and serotonin (5-HT) were also examined. Intracisternal administration of BMAA decreased NA levels in hypothalamus, whereas no effects were seen on DA or 5-HT levels. Following intranigral injections of BOAA, NA levels tended to decrease in several regions, whereas the DA levels and the levels of DA metabolites were unaffected in all regions analyzed. Loss of tyrosine hydroxylase (TH) immunoreactivity in the intranigral injection sites and the presence of TH-immunoreactive pyknotic neurons near the borders of the injection sites were observed following both BOAA and BMAA treatments. Furthermore, substance P-immunoreactive terminals in substantia nigra pars reticulata were also found to have disappeared within the lesioned area following either BOAA or BMAA injections. Incubations with both BOAA and BMAA (10(-5) M) reduced high-affinity [3H]NA uptake in cortical synaptosomes to 69% and 41% of controls, respectively, whereas the striatal high-affinity [3H]DA uptake and the cortical high-affinity [3H]5-HT uptake were unaffected by BOAA or BMAA. The results demonstrate that both BOAA and BMAA can affect central monoamine neurons, although the potency and specificity of these substances on monoamine neurons when administered acutely into cerebral tissue or liquor cerebri seem to be low. However, the in vitro studies indicate selective effects of both compounds on NA neurons in synaptosomal preparations.     

Site of reovirus replication in liver is determined by the type of hepatocellular insult.

Reovirus type 1 strain Lang is restricted from replicating in adult murine livers. In noninjured livers, approximately 1% of hepatocytes express reovirus antigen during infection. However, hepatocytes can be induced to express reovirus antigen if challenged with either toxins or trauma. We used selective hepatotoxins or surgical trauma to demonstrate that reovirus antigen localization in liver is determined by the site of hepatocellular insult and the timing of the virus inoculum.     

Folylpolyglutamate Derivatives of Pisum sativum L. Determination of Polyglutamate Chain Lengths by High Performance Liquid Chromatography Following Conversion to p-aminobenzoylpolyglutamates

The folypolyglutamate derivatives of pea seedlings (Pisum sativumL. cv. Homesteader) were extracted in the presence of 2-mercaptoethanoland cleaved to p-aminobenzoylpolyglutamates by treatment withZn-HCl. Azo dyes were formed by reaction with naphthylethylenediamine and purified by polyacrylamide gel chromatography. p-Aminobenzoylpolyglutamateswere regenerated from these dyes by Zn treatment and then concentratedin vacuo. These derivatives were separated according to glutamylchain length by high performance liquid chromatography on WhatmanPartisil SAX columns. The folylpolyglutamates of 4 day old peacotyledons, pea leaves and isolated chloroplasts were mainlytetra- and pentaglutamates. These and folates of shorter chainlength were labelled when seeds and aerial shoots were incubatedwith p-aminobenzoate-[¹⁴C]. Labelling of the pentaglutamatewas reduced in seeds that were imbibed in the presence of 0.1mM methotrexate. Studies of cotyledon folylpolyglutamate synthetaseshowed that polyglutamate chain length was affected by incubationtime and the concentration of tetra-hydrofolate monoglutamatein the reaction system. ¹Present address: Department of Biology, University of Lethbridge,Alberta, Canada T1K 3M4 ²Present address: Department of Horticulture, Xiong-yue AgriculturalCollege, Xiong-yue, Liaoning Province, China (Received August 4, 1989; Accepted December 5, 1989)     

Polymorphisms of the apolipoprotein and angiotensin converting enzyme genes in young North Karelian patients with coronary heart disease

The genes encoding apolipoproteins (apos) A-I, B, C-III and E as well as that encoding the angiotensin converting enyzme (ACE) have been proposed as candidate genes for coronary heart disease (CHD). We determined the common polymorphisms of the apo genes, previously found to influence serum lipid levels at the population level, and the insertion/deletion polymorphism of the ACE gene, recently reported to reflect the risk of myocardial infarction, in 82 very young (mean, 41 years) North Karelian Finns with symptomatic CHD and 50 controls of similar age. Patients with familial hypercholesterolemia had been excluded from this material. None of the polymorphisms examined, including the apo A-I promoter MspI, apo C-III SstI and apo B XbaI restriction fragment polymorphisms, a common variation of apo E (2, 3 and 4 alleles) and an ACE insertion/deletion (I/D) polymorphism, was significantly associated with the risk of premature CHD. Patients with CHD had a higher mean serum LDL cholesterol/HDL cholesterol ratio than controls (3.15±1.30 vs 2.72±0.98, P < 0.05), but no significant associations between the common apo gene polymorphisms and serum lipid levels were disclosed in either group. It is possible that other genetic loci than those proposed to be associated with accelerated atherosclerosis may be more important as risk factors of symptomatic CHD at the age of 40 years.     

Supercritical carbon dioxide extraction of hydrocarbons from the microalgaBotryococcus braunii

Samples of the microalgaBotryococcus braunii were submitted to supercritical fluid extraction with carbon dioxide at 40 °C and pressures of 12.5, 20.0 and 30.0 MPa. The extraction yield and the fraction of the hydrocarbons in the extracts both increased with pressure and at 30 MPa these compounds were obtained rapidly. This behaviour is associated with the localization of the hydrocarbons outside the cell wall. In the extracts, which are fluid, golden and limpid, chlorophyll and phospholipids were not detected.Author for correspondence