Deodorizing effects of tea catechins on amines and ammonia

Deodorizing effects of tea catechins on amines were examined under alkaline conditions to eliminate the neutralization reaction. They showed deodorizing activity on ethylamine, but none on dimethylamine or trimethylamine. Deodorizing activity on ethylamine was found to be in the order of (-)-epigallocatechin gallate > gallic acid > (-)-epigallocatechin (EGC) > (-)-epicatechin gallate > ethyl gallate > (+)-catechin = (-)-epicatechin. Further, reaction products of EGC with methylamine, ethylamine, and ammonia were detected by HPLC, indicating that a deodorizing reaction other than neutralization occurs. From structural analysis of the reaction product with the methylamine isolated as a peracetylated derivative, the product was presumed to be methylamine substituted EGC, in which the hydroxyl group of EGC at the 4' position is replaced by the methylamino group. The same replacement reaction took place in the case of ethylamine and ammonia.     

cDNA microarray analysis of altered gene expression in Ara-C-treated leukemia cells

The acute lymphoblastic leukemia cell line CCRF-CEM is sensitive to Ara-C and undergoes apoptosis. In contrast, the chronic myelogenous leukemia (CML) cell line K562 is highly resistant to Ara-C, which causes the cells to differentiate into erythrocytes before undergoing apoptosis. We used cDNA microarrays to monitor the alterations in gene expression in these two cell lines under conditions leading to apoptosis or differentiation. Ara-C-treated CCRF-CEM cells were characterized by a cluster of down-regulated chaperone genes, whereas Ara-C-treated K562 cells were characterized by a cluster of up-regulated hemoglobin genes. In K562 cells, Ara-C treatment induced significant down-regulation of the asparagine synthetase gene, which is involved in resistance to L-asparaginase. Sequential treatment with Ara-C and L-asparaginase had a synergistic effect on the inhibition of K562 cell growth, and combination therapy with these two anticancer agents may prove effective in the treatment of CML, which cannot be cured by either drug alone.     

Complex protein interactions within the human polyadenylation machinery identify a novel component

Polyadenylation of mRNA precursors is a two-step reaction requiring multiple protein factors. Cleavage stimulation factor (CstF) is a heterotrimer necessary for the first step, endonucleolytic cleavage, and it plays an important role in determining the efficiency of polyadenylation. Although a considerable amount is known about the RNA binding properties of CstF, the protein-protein interactions required for its assembly and function are poorly understood. We therefore first identified regions of the CstF subunits, CstF-77, CstF-64, and CstF-50, required for interaction with each other. Unexpectedly, small regions of two of the subunits participate in multiple interactions. In CstF-77, a proline-rich domain is necessary not only for binding both other subunits but also for self-association, an interaction consistent with genetic studies in Drosophila. In CstF-64, a small region, highly conserved in metazoa, is responsible for interactions with two proteins, CstF-77 and symplekin, a nuclear protein of previously unknown function. Intriguingly, symplekin has significant similarity to a yeast protein, PTA1, that is a component of the yeast polyadenylation machinery. We show that multiple factors, including CstF, cleavage-polyadenylation specificity factor, and symplekin, can be isolated from cells as part of a large complex. These and other data suggest that symplekin may function in assembly of the polyadenylation machinery.     

Native and non-native conformation-specific antibodies directed to the loop region of hen egg-white lysozyme

Two types of antibodies were differentiated in conventional guinea pig anti-hen egg-white lysozyme (HEL) antisera. The specificities of both antibodies were directed to the loop I region (mainly directed to Cys64--Cys80 loop) but the antibodies were distinct in respect of reactivities with native HEL. One type of antibody reacted with HEL and loop-peptides of HEL but not with the completely reduced and carboxymethylated form of loop-peptides (native conformation specific antibody: NC-Ab). On the other hand, the other type of antibody did not react with HEL but reacted with loop-peptides and also with the completely reduced and carboxymethylated form of loop-peptides (non-native conformation specific antibody: NNC-Ab). The percentage of NNC-Ab in loop I reactive antibody fraction from pooled guinea pig anti-HEL antisera obtained by two different immunization methods was about 25%. Since the affinities of the NNC-Ab to loop-related peptides were higher by one order of magnitude than those of the NC-Ab to the same peptides, care is necessary in evaluating antigenic determinants in native protein. The immunization of guinea pigs with Ploop I . II [sequence 57-107 (Cys64-Cys80, Cys76-Cys94)] evoked an antibody population having specificity similar to but not identical with that of the NNC-Ab type anti-loop I antibody in conventional anti-HEL antisera.     

Preparation and application of a fluorogenic substrate for endo-beta-xylosidase

The present paper describes a fluorometric assay for galactosaminoglycan-degrading endo-beta-xylosidase, utilizing glycosaminoglycan chains bearing a 4-methylumbelliferyl group at the reducing terminus as a substrate. This fluorogenic substrate is synthesized by human skin fibroblasts cultured in the presence of a fluorogenic xyloside, 4-methylumbelliferyl-beta-D-xyloside. The assay is based on measurement of the fluorescence of 4-methylumbelliferone, enzymatically liberated from the synthetic substrate by endo-beta-xylosidase. We examined the applicability of the assay for analysis of endo-beta-xylosidase activity.     

Cleavage of the xylosyl serine linkage between a core peptide and a glycosaminoglycan chain by cellulases

We previously found that endo-beta-xylosidase from Patinopecten is an endo-type glycosidase that cleaves the xylosyl serine linkage between a glycosaminoglycan chain and its core protein (Takagaki, K., Kon, A., Kawasaki, H., Nakamura, T., Tamura, S., and Endo, M. (1990) J. Biol. Chem. 265, 854-860). Screening for endo-beta-xylosidase activity in several cellulases detected this activity in the enzymes from Aspergillus niger, Penicillium funiculosum, Trichoderma reesei, Trichoderma viride, and Irpex lacteus. The cellulase derived from A. niger was purified, and its molecular weight was determined to be 26,000 by SDS-PAGE. Examination of the specificity of the cellulase revealed that 1) the enzyme acts on the linkage region (xylosyl serine) between a core peptide and a glycosaminoglycan chain; 2) enzymatic activity is greater with shorter glycosaminoglycan chains; 3) the enzyme readily hydrolyzes the linkage in glycosaminoglycan peptides, but intact proteoglycan is cleaved only slowly; and 4) the activity is unaffected by the glycosaminoglycan component (chondroitin sulfate, dermatan sulfate, and heparan sulfate). Judging from these enzymatic characteristics, this cellulase is different from the endo-beta-xylosidase of Patinopecten. We believe that this cellulase will become a useful tool in the further development of glycotechnology, because, like the endo-beta-xylosidase of Patinopecten, it enables the release of intact glycosaminoglycans from glycosaminoglycan peptides.     

Junctional sequences of T cell receptor gamma delta genes: implications for gamma delta T cell lineages and for a novel intermediate of V-(D)-J joining

Nucleotide sequences of a large number of V-(D)-J junctions of T cell receptor (TCR) gamma and delta genes show that most fetal thymocytes express on their surface one of just two gamma delta TCRs known to be expressed by epidermal gamma delta T cells (s-IEL) or intraepithelial gamma delta T cells associated with female reproductive organs (r-IEL). In contrast, gamma delta TCRs expressed on adult thymocytes are highly diverse as a result of multiple combinations of gene segments as well as junctional deletions and insertions, indicating that developmental time-and cell lineage-dependent mechanisms exist that control the extent of gamma delta TCR diversity. In addition, this study revealed a new type of junctional insertion (P nucleotides), which led to a new model of V-(D)-J joining generally applicable to immunoglobulin and TCR genes.     

Casein digestion by Debaryomyces hansenii isolated from cheese

To understand the possible proteolytic contribution of yeast during cheese ripening, Debaryomyces hansenii 212 was isolated from commercial blue-veined cheese and incubated in a medium containing casein. Growth and casein degradation were recognized at the cheese-ripening temperature. Proteolytic activity was found in the intracellular fraction, and the enzyme, which was attached to the cell wall, primarily acted on beta-casein. The cytosol contained more than 90% of the total proteolytic activity which was responsible for the degradation of both alpha(s)- and beta-casein. These results suggest that the contribution of yeast to cheese ripening would depend on the susceptibility to cell lysis in addition to its proteolytic activity.     

Monoclonal antibodies that recognize the trisaccharide epitope Galα1-3Galβ1-4GlcNAc present on Ehrlich tumor cell membrane glycoproteins

Monoclonal antibodies were prepared against the trisaccharide Gal1-3Gal1-4GlcNAc, a sequence which occurs on the surface of Ehrlich ascites tumor cells as well as in thyroglobulin, laminin and a variety of other proteins. This was accomplished by immunizing BALB/c mice with the fraction of Ehrlich cell membrane glycoproteins obtained by affinity chromatography on aGriffonia simplicifolia I (GS I) column which selectively binds -d-galactosyl-terminated structures. Detection of Gal1-3Gal1-4GlcNAc-specific antibodies was accomplished by employing glycoproteins containing the trisaccharide sequence; fusion with spleen cells from an immunized mouse was accomplished in the presence of polyethylene glycol (PEG1500). An enzyme-linked immunosorbent assay (ELISA) system was used to identify two clones (2.10G and 6.8E), which recognized the desired trisaccharide conjugate. These clones also recognized a thyroglobulin fraction isolated by GS I affinity chromatography and murine laminin, both of which possess the Gal1-3Gal1-4GlcNAc sequence. Inhibition of antibody-trisaccharide reactivity, examined employing an ELISA assay, revealed that two trisaccharides, Gal1-3Gal1-4GlcNAc/Glc, were the best inhibitory haptens; Gal1-4GlcNAc (LacNAc), Gal1-3Gal and Gal1-4Glc (lactose) were poor inhibitors. Indirect immunofluorescence staining of unfixed Ehrlich cells using the monoclonal antibody at 4° C revealed fluorescence over the entire cell surface. Indirect immunogold labeling of semithin and ultrathin sections of aldehyde fixed and Lowicryl K4M-embedded Ehrlich cells resulted in specific labeling of the cell surface and internal structure. Immunoblot analysis revealed that removal of the -galactosyl residues of laminin by -galactosidase abolished reactivity with the monoclonal antibodies. The availability of this antibody, which belongs to the IgM family of immunoglobulins, now makes possible the detection of this sugar sequence on cells and tissue sections, as well as on glycoproteins in solution.