Acceptor specificity of the human leukocyte alpha3 fucosyltransferase: role of FucT-VII in the generation of selectin ligands

The alpha3 fucosyltransferase, FucT-VII, is one of the key glycosyltransferases involved in the biosynthesis of the sialyl Lewis X (sLex) antigen on human leukocytes. The sialyl Lewis X antigen (NeuAcalpha(2-3)Galbeta(1-4)[Fucalpha(1-3)]GlcNAc-R) is an essential component of the recruitment of leukocytes to sites of inflammation, mediating the primary interaction between circulating leukocytes and activated endothelium. In order to characterize the enzymatic properties of the leukocyte alpha3 fucosyltransferase FucT-VII, the enzyme has been expressed in Trichoplusia ni insect cells. The enzyme is capable of synthesizing both sLexand sialyl-dimeric-Lexstructures in vitro , from 3'-sialyl-lacNAc and VIM-2 structures, respectively, with only low levels of fucose transfer observed to neutral or 3'-sulfated acceptors. Studies using fucosylated NeuAcalpha(2-3)-(Galbeta(1- 4)GlcNAc)3-Me acceptors demonstrate that FucT-VII is able to synthesize both di-fucosylated and tri-fucosylated structures from mono- fucosylated precursors, but preferentially fucosylates the distal GlcNAc within a polylactosamine chain. Furthermore, the rate of fucosylation of the internal GlcNAc residues is reduced once fucose has been added to the distal GlcNAc. These results indicate that FucT-VII is capable of generating complex selectin ligands, in vitro , however the order of fucose addition to the lactosamine chain affects the rate of selectin ligand synthesis.      

The influence of learning on the "setting" of the spinal apparatus of reciprocal inhibition prior to voluntary motion]

The subjects performed daily for nine days from 200 to 250 single movements, namely a rapid dorsal flexion of the foot. Recording of the EMG of antagonist muscles and testing by the single and paired H-reflexes method has revealed three phenomena of learning: greater ratio of electrical activity (EA) of antagonist muscles owing to the enhanced agonist's EA; stronger reciprocal inhibition of the antagonist motoneurone nucleus at the beginning of the movement; enhanced supraspinal "tuning" of the spinal apparatus of the antagonist reciprocal inhibition before the beginning of the movement. It is suggested that the third phenomenon of learning underlies two phenomena.     

Neuroprotective effect of N-acylethanolamines in chronic morphine dependence. I. Rat brain phospholipids as a target of their action

The influence of saturated and unsaturated N-acylethanolamines (NAEs) mixture on the rat brain lipid composition under the chronic morphine dependence was studied. It was shown that the long-term administration of NAE to rats with experimental morphine dependence restored the morphine-induced alterations of the brain phospholipid composition. This effect can probably be explained by a fatty acyl transfer from NAE to sn-1 position of some brain glycerophospholipids. Another reason of NAE beneficial effect could be due to its antioxidative property, thus providing the remodelling of phospholipid composition. The restoration of the brain essential phospholipids is associated with the decline in morphine consumption in rats with experimental morphine dependence. The mechanism of this phenomenon requires further investigations.     

Phosphinic analog of methionine inhibits growth of leucosis cell L1210 and transforms to phosphinic analog of S-adenosylmethionine

A phosphinic analogue of methionine bearing a phosphinic H(OH)(O)P fragment in place of the carboxyl group inhibited the growth of the L1210 cells and was intracellularly transformed to the phosphinic analogue of S-adenosylmethionine.     

Effect of fungal infection on the composition of acyl lipids in wheat seedlings

Infection of etiolated wheat seedlings with a root rot fungus Bipolaris sorokiniana caused a strong deviation in the fatty acid composition of their total lipids from the control. The deviation occurred at the expense of that lipid group, which predominates in a given plant organ (shoots or roots), and peak deviation coincided with the onset of a severe inhibition of growth.     

Conservative mutation Met8 --> Leu affects the folding process and structural stability of squash trypsin inhibitor CMTI-I

Protein molecules can accommodate a large number of mutations without noticeable effects on their stability and folding kinetics. On the other hand, some mutations can have quite strong effects on protein conformational properties. Such mutations either destabilize secondary structures, e.g., alpha-helices, are incompatible with close packing of protein hydrophobic cores, or lead to disruption of some specific interactions such as disulfide cross links, salt bridges, hydrogen bonds, or aromatic-aromatic contacts. The Met8 --> Leu mutation in CMTI-I results in significant destabilization of the protein structure. This effect could hardly be expected since the mutation is highly conservative, and the side chain of residue 8 is situated on the protein surface. We show that the protein destabilization is caused by rearrangement of a hydrophobic cluster formed by side chains of residues 8, Ile6, and Leu17 that leads to partial breaking of a hydrogen bond formed by the amide group of Leu17 with water and to a reduction of a hydrophobic surface buried within the cluster. The mutation perturbs also the protein folding. In aerobic conditions the reduced wild-type protein folds effectively into its native structure, whereas more then 75% of the mutant molecules are trapped in various misfolded species. The main conclusion of this work is that conservative mutations of hydrophobic residues can destabilize a protein structure even if these residues are situated on the protein surface and partially accessible to water. Structural rearrangement of small hydrophobic clusters formed by such residues can lead to local changes in protein hydration, and consequently, can affect considerably protein stability and folding process.     

Neuroprotective effect of N-acylethanolamines in chronic morphine dependence. II. Effect on the rat brain fatty acid composition

The effect of N-acylethanolamines mixture (NAE) with saturated and unsaturated acyl chains on the fatty acid composition of the rat brain under chronic morphine dependence was investigated. Long-term administration of NAE reduced morphine-induced decrease of mono- and polyunsaturated fatty acids in the rat brain crude lipid extract. Furthermore, NAE restored the acyl chain spectrum, especially the content of docosahexaenoic acid in essential phospholipids--phosphatidylcholine and phosphatidylethanolamine. Pharmacological activity of NAE depended on a dose.