Selective Oxidation of 2′-Deoxyguanosine to Imidazolone by the Chemical Nuclease MnTMPyP Associated to KHSO5 or Sulfite/O2.

Abstract

Mn TMPyP in the presence of sulfite/O₂ catalyses the oxidation of dG into dIz as selectively but slower and less efficiently than in the presence of KHSO_5.     

Expression of a C3 plant Rubisco SSU gene in regenerated C4 Flaveria plants

We report the successful transformation, via Agrobacterium tumefaciens infection, and regeneration of two species of the genus Flaveria: F. brownii and F. palmeri. We document the expression of a C₃ plant gene, an abundantly expressed ribulose 1,5-bisphosphate carboxylase/oxygenase small subunit gene isolated from petunia, in these C₄ plants. The organ-specific expression of this petunia gene in Flaveria brownii is qualitatively identical to its endogenous pattern of expression.     

Is phospholipid a required cofactor for the activity of mammalian signal peptidase?

To determine whether phospholipid is required for the activity of mammalian signal peptidase, the enzyme was partially purified from porcine pancreas and then extensively freed of phospholipid by SP-Sephadex C-50 chromatography. The delipidated enzyme showed signal peptidase activity, with a low concentration of detergent. Phospholipid was found to release the enzyme from the inhibition due to excess detergent.     

Effects of muscle glycogen and plasma FFA availability on human metabolic responses in cold water.

The purpose of this study was to investigate whether simultaneous alterations in the availability of plasma free fatty acids and muscle glycogen would impair the maintenance of thermal balance during cold water immersion in humans. Eight seminude subjects were immersed on two occasions in 18 degrees C water for 90 min or until rectal temperature (Tre) decreased to 35.5 degrees C. Each immersion followed 2.5 days of a specific dietary and exercise regimen designed to elicit low (LOW) or high glycogen levels (HIGH) in large skeletal muscle groups. Nicotinic acid (1.6 mg/kg) was administered for 2 h before and during immersion to inhibit white adipose tissue lipolysis. Biopsies from the vastus lateralis showed that the glycogen concentration before the immersion was significantly lower in LOW than in HIGH (223 +/- 19 vs. 473 +/- 24 mmol glucose units/kg dry muscle). However, the mean rates of glycogen utilization were not significantly different between trials (LOW 0.62 +/- 0.14 vs. HIGH 0.88 +/- 0.15 mmol glucose units.kg-1.min-1). Nicotinic acid dramatically reduced plasma free fatty acid levels in both trials, averaging 127 +/- 21 mumol/l immediately before the immersion. Cold water immersion did not significantly alter those levels. Plasma glucose levels were significantly reduced after cold water immersion to a similar extent in both trials (18 +/- 4%). Mean respiratory exchange ratio at rest and during immersion was greater in HIGH than LOW, whereas there were no intertrial differences in O2 uptake. The calculated average metabolic heat production during immersion tended to be lower (P = 0.054) in LOW than in HIGH (15.3 +/- 1.9 vs. 17.5 +/- 1.9 kJ/min).(ABSTRACT TRUNCATED AT 250 WORDS)     

The use of N-urethane-protected N-carboxyanhydrides (UNCAs) in amino acid and peptide synthesis

N-Urethane-protected N-carboxyanhydrides (UNCAs) are very reactives. They have been successfully used in peptide synthesis, in both solution and solid phase. We have demonstrated that UNCAs are interesting starting materials for the synthesis of various amino acid derivatives. Chemoselective reduction of UNCAs with sodium borohydride led the corresponding N-protected β amino alcohols. Reaction of UNCAs with Meldrum's acid, followed by cyclisation, yielded enantiomerially pure tetramic acid derivatives. Diastereoselective reduction of tetramic acid derivatives produced (4S,5S)-N-alkoxycarbonyl-4-hydroxy-5-alkylpyrrolidin-2-ones derived from amino acids, which after hydrolysis yielded statine and statine analogues. Tetramic acid derivatives could also be obtained by reaction of UNCAs with benzyl ethyl followed by hydrogenolytic deprotection and decarboxylation. UNCAs also reacted with phosphoranes to produce the ketophosphorane in excellent yields. Subsequent oxidation with oxone or with [bis(acetoxy)-iodol]-benzene produced vicinal tricarbonyl derivatives. These reactions usually proceeded smoothly and with high yields.     

Evolutionary study of multigenic families mapping close to the human MHC class I region

Summary During a search for novel coding sequences within the human MHC class I region (chromosome 6p21.3), we found an exon (named B30-2) coding for a 166-amino-acid peptide which is very similar to the C-terminal domain of several coding sequences: human 52-kD Sjögren's syndrome nuclear antigen A/Ro (SS-A/Ro) and ret finger protein (RFP), Xenopus nuclear factor 7 (XNF7), and bovine butyrophilin. The first three of these proteins share similarities over the whole length of the molecule whereas butyrophilin is similar in the C-terminal domain. The N-terminal domain of butyrophilin is similar to rat myelin/oligodendrocyte glycoprotein (MOG) and chicken B blood group system (B-G) protein. These domains are components of a new subfamily of the immunoglobulin superfamily (IgSF). Butyrophilin is thus a mosaic protein composed of the MOG/B-G Ig-like domain and the C-terminal domain of 52-kD SS-A/Ro, RFP, and XNF7 (1330-2-like domain). Moreover, in situ hybridization shows that RFP, butyrophilin, and MOG map to the human chromosome 6p2l.3-6p22 region and are thus close to the MHC class I genes. It is therefore possible that the butyrophilin gene is the product of an exon shuffling event which occurred between ancestors of the RFP and MOG genes. To our knowledge, this is the first example of the colocalization of a chimeric gene and its putative progenitors. Finally, regulatory protein T-lymphocyte 1 (Rpt-1) shares similarities with the N-terminal halves of RFP, 52-kD SS-A/Ro, and XNF7, but not with the B30-2-like domain. We show that the ancestral Rpt-l gene evolved by overprinting. Correspondence to: P. Pontarotti     

Isolation, sequence, and expression in Escherichia coli of the Pseudomonas sp. strain ACP gene encoding 1-aminocyclopropane-1-carboxylate deaminase.

Pseudomonas sp. strain ACP is capable of growth on 1-aminocyclopropane-1-carboxylate (ACC) as a nitrogen source owing to induction of the enzyme ACC deaminase and the subsequent conversion of ACC to alpha-ketobutyrate and ammonia (M. Honma, Agric. Biol. Chem. 49:567-571, 1985). The complete amino acid sequence of purified ACC deaminase was determined, and the sequence information was used to clone the ACC deaminase gene from a 6-kb EcoRI fragment of Pseudomonas sp. strain ACP DNA. DNA sequence analysis of an EcoRI-PstI subclone demonstrated an open reading frame (ORF) encoding a polypeptide with a deduced amino acid sequence identical to the protein sequence determined chemically and a predicted molecular mass of 36,674 Da. The ORF also contained an additional 72 bp of upstream sequence not predicted by the amino acid sequence. Escherichia coli minicells containing the 6-kb clone expressed a major polypeptide of the size expected for ACC deaminase which was reactive with ACC deaminase antiserum. Furthermore, a lacZ fusion with the ACC deaminase ORF resulted in the expression of active enzyme in E. coli. ACC is a key intermediate in the biosynthesis of ethylene in plants, and the use of the ACC deaminase gene to manipulate this pathway is discussed.     

Synthesis of Tricyclic Phenylpyrrole Lactams, New Models of Antitubulin Agents

The tricyclic lactams 3 and 4 having a phenylpyrrole framework have been prepared from the arylpyrroles 5 and 16 respectively. These structural analogs of rhazinilam 1 present, like the latter, an interesting antitubulin and cytotoxic activity.     

Metabolic effect at six and twelve months of cyproterone acetate (2 mg) combined with ethinyl estradiol (35 micrograms) in 31 patients

The metabolic effects of cyproterone acetate (2 mg) combined with a new dose level of ethinyl estradiol (35 micrograms) were studied over a one-year period in 31 patients presenting moderate clinical hyperandrogenism. The following tests were performed before treatment, at 6 and 12 months, an oral glucose tolerance test (OGTT) with measurement of insulinemia, total cholesterol, HDL cholesterol and the LDL + VLDL/HDL ratio, A1 and B apoproteins. At six months and at one year of treatment, the weight and body mass index (kg/m2) were not modified. Glucose tolerance and insulinemia had not changed significantly at one year. Lipid test results showed an increase in triglycerides, as well as in total and HDL cholesterol levels. However, the LDL + VLDL/HDL and A1/B apoprotein ratios did not change during the study. We conclude from these results that the new combination does not have any adverse effects on glucose tolerance and has a predominantly estrogenic effect on lipid parameters, characterized by increases in total cholesterol, HDL cholesterol and triglycerides.