Quantitative determination of the activity of acid peptidases of industrial origin]

Reagent ninhydrine-Cd++, reacts with free alpha and epsilon amino groups of proteins. Horse-heart apomyoglobin was subjected to exhaustive succinylation, rendering the product non reactive to ninhydrine. The succinylglobin was submitted to enzyme digestion at pH 2.0, 4.0, 4.7 and 6.0. The commercially available enzymes contain mainly pepsin-like and chymosin-like enzymes. The enzymatic digests of succinyl-globin contain new free alpha-amino groups reacting with ninhydrin. Enzymatic digestion was performed under various condition (ratio E/S, pH). The results were compared to those obtained with synthetic substrate: PRO-HIS-LEU-SER-PHE(NO2)-NLEU-ALA-LEU-OME. The price of the synthetic substrate used, was more than 100 times the cost of succinyl-globin, thus the use of this substrate is a valuable tool for the quantitative estimation of peptidase activity in commercially available (pepsin, chymosin-like) enzymes.     

Role and origin of the centriole]

The centriole could constitute a system of inertia in the cell, providing the system of references controlling the movement of the cell. It would ensure equally the coherence of cell metabolism and its stability. The origin and functioning of the centriole would be linked to a singel physical phenomenon.     

Macrophage origin of platelet activating factor]

Platelet-activating factor (P.A.F.) is a mediator of anaphylaxis released from human and Rabbit basophils which causes aggregation of platelets and release of their vasoactive amines. We have induced the release of P.A.F. from Rat peritoneal cells (P.C.) with ionophore A 23187. After fractionation of P.C. on 5-15% Ficoll gradients, P.A.F. was obtained from macrophage-rich but not from mastocyte-rich fractions and from adherent cells but not from non adherent cells. These data suggest an important new function for the macrophage: aggregation of platelets and release of their vasoactive amines and others mediators of inflammation.     

Running activity of ovarian tumorigenic mice

Résumé Les ovaires de souris C3B6F1, génotypeW ^xW^v développent des adénomes tubulaires à l'âge de 7 mois. Dans l'essai du tread wheel l'activité spontanée de ces animaux était plus petite que celle des contrôles.     

Detection and localization of a ribonuclease activity associated with vaccinia virus]

A ribonuclease associated with vaccinia virus can be detected when reduced concentrations of nucleotides are used for an in vitro RNA synthesis assay. The non-viral origin of this ribonuclease may be inferred from its external location and from its variable activity on different purified virus stocks. The detection of this ribonuclease activity on purified virus grown without foetal Calf serum may suggest that this enzyme is of cellular origin.     

Influence of testicular fluid, spermatozoa and androgens on physiological activity of rat epididymis]

By ligation of the efferent duct and the corpus epididymis, the GPC concentration in this delimited anterior region decreased. However, HCG infection increased the GPC concentration. When spermatozoa are present in the epididymal tubule there is always a decrease in GPC concentration in these experimental conditions. Activity of the epididymis is disturbed by ligation.     

A gas chromatographic study of the composition of neutral and amino sugars in two neuraminidases, of bacterial and viral origin]

The neutral and aminosugar composition has been determined by gas-liquid chromatography for two neuraminidases, either bacterial, from Streptococcus pneumoniae, or viral, from Myxovirus influenzae A/Hong Kong/1/68.     

Inhibitory effects of LHRH on ovarian LH receptors in rats]

The administration of LHRH or of its analog [D-Ala6, des-Gly-NH10(2)] LHRH ethylamide to the female rat on day 10 of gestation resulted in termination of pregnancy and in a marked decrease in ovarian LH receptors and plasma progesterone level. Asingle injection of either compound during diestrus I also led to a decrease in LH receptors. These data demonstrate the high sensitivity of the control of ovarian LH receptors by circulating gonadotrophins and suggest that the contraceptive action of pre- and postcoitally administered LHRH is mediated by negative control of LH receptors.     

Lipoxygenase activity of wheat seeding chloroplasts]

Chloroplasts have been isolated from Wheat shoots by density gradient centrifugation. When added to a linoleic acid and Tween 20 suspension these chloroplasts induce an oxygen consumption. The hydroperoxides synthesized from linoleic and oxygen have been characterized by spectrophotometry and thin layer chromatography.     

Ligase activity of lig- bacteria infected with mu bacteriophage at non-permissive temperatures]

Infection of bacteria E. coli lig ts7, which contain a thermosensitive ligase by phage Mu results in a decrease in the sensitivity to the lethal action of ultraviolet irradiation and stimulation of lysogenization among the surviving cells. These observations suggest the existence of a phage coded ligase which has the character of an integrase.     

Effects of ovarian steroids on superoxide dismutase activity in the rat brain

The levels of manganese superoxide dismutase (MnSOD) and copper-zinc superoxide dismutase (CuZnSOD) were determined in appropriate subcellular fractions prepared from whole brain homogenates of cycling and long-term (3 week) ovariectomized (OVX) Wistar rats, and were compared to the levels found in corresponding samples prepared from OVX rats treated with progesterone (P) or estradiol 17B-benzoate (EB). The activity of both SODs was steady during the estrous cycle, except at proestrus, when MnSOD activity was elevated significantly. Bilateral ovariectomy resulted three weeks later in an increase of the MnSOD activity even higher than that recorded at proestrus. High post-castration MnSOD activity was lowered profoundly by exogenous P (2 mg) or EB (0.5 g), given s.c. to OVX animals 2 h or 24 h before sacrifice. Neither removal of the ovaries nor the hormone treatments affected the activity of CuZnSOD. These results suggest suppressive effects of ovarian steroids on MnSOD activity in the rat brain.     

The origin,diversity, and structure function relationships of insect luciferases

Luciferases are the enzymes that catalyze the reactions that produce light in bioluminescence. Whereas the oxidative mechanism which leads to light emission is similar for most luciferases, these enzymes and their substrates are evolutionarily unrelated. Among all bioluminescent groups, insects constitute one of the most diverse in terms of biochemistry. In the fungus-gnats (Mycetophilidae: Diptera), for example, bioluminescence is generated by two biochemically distinct systems. Despite the diversity, investigations on insect luciferases and biochemistry have been conducted mostly with fireflies. The luciferases from the related phengodid beetles, which can produce green to red bioluminescence using the same chemistry as firefly luciferases, have been recently investigated. Beetle luciferases originated from ancestral acyl-CoA ligases. Present data suggest that conserved motifs among this class of ligases are involved in substrate adenylation. The three-dimensional structure of firefly luciferase was recently solved and mutagenesis studies have been performed identifying putative residues involved in luciferin binding and bioluminescence color determination in several beetle luciferases. The knowledge gained through these studies is helping in the development of useful reporter gene tools for biotechnological and biomedical purposes. Received 4 March 2002; received after revision 13 May 2002; accepted 21 May 2002     

TRH analogue with C-terminal thioamide group. Synthesis, receptor binding, TSH-releasing activity and alpha-MSH-releasing activity

A new TRH analogue containing a C-terminal thioamide group was synthesized. This peptide was shown to have receptor-binding affinity, and TSH- as well as alpha-MSH-releasing activities very similar to native TRH.     

Alpha-mannosidase activity of different human biological fluids]

Two distinct alpha-mannosidases have been found in biological fluids by investigating the effect of pH on activity, the effect of Co2+ and Zn2+ and by determining the Michaelis constant. The two enzymes are designated as S, predominating in serum (optimum pH about 5.6) and U, predominating in urine (optimum pH about 4.2). In cerebro-spinal fluid, the amount of alpha-mannosidase S is almost the same as that of alpha-mannosidase U. Alpha-mannosidase S activity in sera is significantly higher in children than in adults.     

Interaction of two isomers, N-nitrosomethylphenylamine, N-nitroso derivative, and p-nitrosomethylaniline with microorganisms]

There exists a relationship between the chemical structure C--NO or N--NO and biological effects. p-nitrosomethylaniline, a C-nitroso compound, in contrast to its isomer, N-nitrosomethylphenylamine, a N-nitroso derivate, shows a marked action against microoganisms and is, alone, reduced enzymatically.