Hyaluronan recognition mode of CD44 revealed by cross-saturation and chemical shift perturbation experiments

CD44 is the main cell surface receptor for hyaluronic acid (HA) and contains a functional HA-binding domain (HABD) composed of a Link module with N- and C-terminal extensions. The contact residues of human CD44 HABD for HA have been determined by cross-saturation experiments and mapped on the topology of CD44 HABD, which we elucidated by NMR. The contact residues are distributed in both the consensus fold for the Link module superfamily and the additional structural elements consisting of the flanking regions. Interestingly, the contact residues exhibit small changes in chemical shift upon HA binding. In contrast, the residues with large chemical shift changes are localized in the C-terminal extension and the first alpha-helix and are generally inconsistent with the contact residues. These results suggest that, upon ligand binding, the C-terminal extension and the first alpha-helix undergo significant conformational changes, which may account for the broad ligand specificity of CD44 HABD.     

2,4-Decadienals are produced via (R)-11-HPITE from arachidonic acid in marine green alga Ulva conglobata

Marine green alga Ulva conglobata was investigated for the biogeneration of oxygenated products from exogenously added arachidonic acid (ARA). A crude enzyme from the alga afforded the detectable amount of a hydroperoxyicosatetraenoic acid (HPITE), which was identified as (R)-11-HPITE by HPLC and GC-MS. Headspace-SPME method indicated that ARA was selectively used to form 2,4-decadienals. These results showed that 2,4-decadienals are produced via (R)-11-HPITE from ARA exclusively.     

Fatty acid hydroperoxide lyase in tobacco cells cultured in vitro

Fatty acid hydroperoxide lyase (HPO lyase) was found in green and non-green tobacco cells cultured in vitro. The HPO lyase activity in non-green cells was $\text{1}\text{3}$-$\text{1}\text{2}$ of that in green cells. When the cells were transferred from the light to dark conditions or vice versa, cells turned non-green or green according to the light conditions. The HPO lyase activity also changed according to the light conditions, but the changes in HPO lyase activities were not proportional to the changes in chlorophyll contents. These results suggest that at least two types of HPO lyases are present in the green cells. One type of HPO lyase is perhaps common both to the green and non-green cells; another one is chloroplastic. The fatty acid compositions of cells and substrate specificities of HPO lyase differed between green and non-green cells.     

Distribution of an enzyme system producing seaweed flavor: conversion of fatty acids to long-chain aldehydes in seaweeds

The long chain aldehyde-forming enzyme (LCAE) activity that catalyzes formation of long chain aldehydes, such as (8Z, 11Z, 14Z)-heptadecatrienal, (8Z, 11Z)-heptadecadienal, (8Z)-heptadermal, (7Z, 10Z, 13Z)-hexadecatrienal and pentadecanal from linolenic acid, linoleic acid, oleic acid and palmitic acid, in that order, occurs in a wide range of green, brown and red seaweeds. The LCAE activity increased with maturation of juvenile fronds of Enteromorpha sp. in culture. Thus, cultivation of seaweeds for flavor foods is of interest. The release of long chain aldehydes from the thallus into the medium was confirmed by a quantitative high performance liquid chromatography of volatile compounds, using a closed loop stripping technique, during the culture of the green alga, Ulva pertusa. This finding suggests physiological roles of long chain aldehydes and LCAE activity in marine ecosystems.     

Subunit composition of alcohol dehydrogenase from Thea sinensis seeds and its substrate specificity for monoterpenes

Alcohol dehydrogenase (alcohol: NAD oxidoreductase, E.C. 1.1.1.1.) was purified from Thea sinensis seeds. Its M.W was 95000 and it was composed of two homogeneous subunits with MWs of 47000. The dissociation into subunits was caused by o-phenanthroline. Substrate specificity for monoterpene alcohols and aldehydes is discussed.     

Na-K-dependent ATPase in red cells and thyroid status

The Relationship between ouabain-sensitive ATPase (Na-K ATPase) activity in erythrocytes and the thyroid status was studied in 36 patients with Graves' disease and 58 patients receiving L-thyroxine (T4) replacement therapy. Forty normal children served as control. Total ATPase activity in 4 untreated hypothyroid patients was significantly reduced (11.0 +/- 4.6 vs 17.3 +/- 4.1 micrograms-P/h/mg-protein, P less than 0.01), and Na-K ATPase was undetectable, both of which were normalized after 4 weeks of L-T4 therapy. Na-K ATPase in hyperthyroid patients was also decreased (0.9 +/- 0.8 vs. 4.0 +/- 2.7, P less than 0.01), but was gradually normalized after 3 months of euthyroid state. Clinically euthyroid children treated with L-T4 were divided into 2 groups with regard to Na-K ATPase activity, normal and low. Analysis of the possible factors producing this difference revealed that, in primary hypothyroidism, the factor appeared to be the endogenous T4 level, while in patients with dwarfism, the secretory capacity of TSH or TSH-releasing hormone (TRH) was contributory. Thus Na-K ATPase activity in red cells remains within the normal range after L-T4 replacement in the presence of a severe degree of primary hypothyroidism or in association with secondary or tertiary hypothyroidism. Other factors such as the L-T4 dose, duration of the therapy, serum T4 and T3 concentrations, were not significantly different in the two groups. These results indicate that (1) Na-K ATPase in red cells is decreased in hyper- or hypothyroid state, (2) restoration of normal activity requires 1-3 months of euthyroid period, and (3) it is a sensitive index of peripheral thyroid status over the preceding few months.     

Molecular cloning and expression of Arabidopsis fatty acid hydroperoxide lyase.

Fatty acid hydroperoxide lyase (HPOL), an enzyme of the octadecanoid pathway that forms carbon-6 aldehydes such as n-hexanal or (Z)-3-hexenal, was cloned from Arabidopsis thaliana as a full-length cDNA. The HPOL activity obtained by expressing the cDNA in Escherichia coli formed n-hexanal from linoleic acid 13-hydroperoxide, whereas linoleic acid 9-hydroperoxide was not a substrate for the enzyme. The HPOL mRNA is expressed at low level in leaves; however, its accumulation can be found in the inflorescence. Wounding or methyl jasmonate treatments increase the mRNA level in leaves. These results indicate that the HPOL gene is up-regulated in leaves in response to wounding and that the enzyme may be an active component of the octadecanoid defense response.     

Immune gene therapy of experimental mouse brain tumor with adenovirus-mediated gene transfer of murine interleukin-4

 We examined the antitumor activity of replication-deficient adenoviral vectors carrying the murine interleukin-4 (IL-4) gene (AdCIL4) using a syngeneic brain tumor model in mice. Mice implanted with malignant astrocytoma cells infected with AdCIL4 survived significantly longer than those in the control groups. Immunocytochemical analysis of the tumors showed that AdCIL4 caused the strong up-regulation of MHC class II antigen expression by the tumor cells and macrophages, and consequent infiltration by CD8⁺ T lymphocytes. This study demonstrates the efficacy of IL-4 gene transfection mediated by adenoviral vectors for intracerebral tumor and characterizes the immunoreaction caused by AdCIL4. Received: 27 August 1999 / Accepted: 12 November 1999