Effects of lipid-derivatized glycosaminoglycans (GAGs), a novel probe for functional analyses of GAGs, on cell-to-substratum adhesion and neurite elongation in primary cultures of fetal rat hippocampal neurons

The effects of glycosaminoglycans (GAG) on cell-to-substratum adhesion and neurite elongation were examined in primary cultures of fetal rat hippocampal neurons using tissue culture dishes coated with GAGs coupled to dipalmitoylphosphatidylethanolamine (PE), a novel probe for biological functions of GAGs. Both chondroitin sulfate conjugate to PE (CS-PE) and hyaluronic acid conjugate to PE (HA-PE) promoted neurite elongation from neurons in a dose-dependent manner when immobilized onto polylysine-coated dishes at various concentrations up to 1.0 microg/ml. The coating of CS-PE or HA-PE at a concentration higher than 1.0 microg/ml resulted in failure of neurite extension and adhesion of neurons to the substrata. In contrast, heparin conjugate to PE (HP-PE) did not exert any effects on neurite elongation or on cell attachment at these concentrations. These findings suggest that GAGs serve as a modulator for neurite elongation during neuronal network formation in the developing central nervous system.

Molecular cloning and expression of chondroitin 4-sulfotransferase

Chondroitin 4-sulfotransferase (C4ST) catalyzes the transfer of sulfate from 3'-phosphoadenosine 5'-phosphosulfate to position 4 of N-acetylgalactosamine residue of chondroitin. The enzyme has been previously purified to apparent homogeneity from the serum-free culture medium of rat chondrosarcoma cells (Yamauchi, A., Hirahara, Y., Usui, H., Takeda, Y., Hoshino, M., Fukuta, M., Kimura, J. H., and Habuchi, O. (1999) J. Biol. Chem. 274, 2456-2463). The purified enzyme also catalyzed the sulfation of partially desulfated dermatan sulfate. We have now cloned the cDNA of the mouse C4ST on the basis of the amino acid sequences of peptides obtained from the purified enzyme by protease digestion. This cDNA contains a single open reading frame that predicts a protein composed of 352 amino acid residues. The protein predicts a Type II transmembrane topology. The predicted sequence of the protein contains all of the known amino acid sequence and four potential sites for N-glycosylation, which corresponds to the observation that the purified C4ST is an N-linked glycoprotein. The amino acid sequence of mouse C4ST showed significant sequence homology to HNK-1 sulfotransferase. Comparison of the sequence of mouse C4ST with human HNK-1 sulfotransferase revealed approximately 29% identity and approximately 48% similarity at the amino acid level. When the cDNA was introduced in a eukaryotic expression vector and transfected in COS-7 cells, the sulfotransferase activity that catalyzes the transfer of sulfate to position 4 of GalNAc residue of both chondroitin and desulfated dermatan sulfate was overexpressed. Northern blot analysis showed that, among various mouse adult tissues, 5.7-kilobase message of C4ST was mainly expressed in the brain and kidney.

Expression of heparan sulphate L-iduronyl 2-O-sulphotransferase in human kidney 293 cells results in increased D-glucuronyl 2-O-sulphation

Functionally important interactions between heparan sulphate and a variety of proteins depend on the precise location of O-sulphate groups. Such residues occur at C-2 of L-iduronic (IdoA) and D-glucuronic acid (GlcA) units, and at C-3 and C-6 of D-glucosamine (GlcN) units. Stable transfection of human embryonic kidney 293 cells with a cDNA encoding mouse mastocytoma IdoA 2-O-sulphotransferase resulted in an approx. 6-fold increase in O-sulphotransferase activity, compared with control cells, as determined using O-desulphated heparin as an acceptor. Structural analysis of endogenous heparan sulphate in the transfected cells, following metabolic labelling with either [(3)H]GlcN or [(35)S]sulphate, showed appreciable formation of -GlcA(2-OSO(3))-GlcNSO(3)- disaccharide units (6% of total disaccharide units; 17% of total O-sulphated disaccharide units) that were essentially absent from heparan sulphate from control cells. The increase in GlcA 2-O-sulphation was accompanied by a decrease in the amount of IdoA formed, whereas overall 2-O-sulphation or 6-O-sulphation remained largely unaffected. These findings indicate that 2-O-sulphation of IdoA and GlcA residues is catalysed by the same enzyme in heparan sulphate biosynthesis.

The occurrence of three isoforms of heparan sulfate 6-O-sulfotransferase having different specificities for hexuronic acid adjacent to the targeted N-sulfoglucosamine

We previously cloned heparan sulfate 6-O-sulfotransferase (HS6ST) (Habuchi, H., Kobayashi, M., and Kimata, K. (1998) J. Biol. Chem. 273, 9208-9213). In this study, we report the cloning and characterization of three mouse isoforms of HS6ST, a mouse homologue to the original human HS6ST (HS6ST-1) and two novel HS6STs (HS6ST-2 and HS6ST-3). The cDNAs have been obtained from mouse brain cDNA library by cross-hybridization with human HS6ST cDNA. The three cDNAs contained single open reading frames that predicted type II transmembrane proteins composed of 401, 506, and 470 amino acid residues, respectively. Amino acid sequence of HS6ST-1 was 51 and 57% identical to those of HS6ST-2 and HS6ST-3, respectively. HS6ST-2 and HS6ST-3 had the 50% identity. Overexpression of each isoform in COS-7 cells resulted in about 10-fold increase of HS6ST activity. The three isoforms purified with anti-FLAG antibody affinity column transferred sulfate to heparan sulfate and heparin but not to other glycosaminoglycans. Each isoform showed different specificity toward the isomeric hexuronic acid adjacent to the targeted N-sulfoglucosamine; HS6ST-1 appeared to prefer the iduronosyl N-sulfoglucosamine while HS6ST-2 had a different preference, depending upon the substrate concentrations, and HS6ST-3 acted on either substrate. Northern analysis showed that the expression of each message in various tissues was characteristic to the respective isoform. HS6ST-1 was expressed strongly in liver, and HS6ST-2 was expressed mainly in brain and spleen. In contrast, HS6ST-3 was expressed rather ubiquitously. These results suggest that the expression of these isoforms may be regulated in tissue-specific manners and that each isoform may be involved in the synthesis of heparan sulfates with tissue-specific structures and functions.

In vitro synthesis of hyaluronan by a single protein derived from mouse HAS1 gene and characterization of amino acid residues essential for the activity

HAS1 was expressed as a FLAG-tagged HAS1 fusion protein in COS-1 cells. This recombinant protein was extracted with CHAPS (3-[(3-cholamidopropyl)dimethylammonio]-1-propanesulfonic acid) from the membrane fraction and purified by anti-FLAG affinity chromatography and subsequent SDS-polyacrylamide gel electrophoresis. A protein solubilized from the one single band on the gel was able to synthesize hyaluronan when incubated with UDP-GlcNAc and UDP-GlcA as donor substrates without any further additions. The detergent-solubilized and purified HAS1 protein, however, exhibited quite different kinetic properties from the membrane-bound protein. When assayed under the reconstitutive conditions where the reaction mixture was layered onto the buffer containing high concentration of CHAPS, the activity was enhanced and the kinetic properties became similar to those of the membrane-bound protein. In addition, a HAS1 gene product by an in vitro transcription/translation system also showed HAS1 activity under the reconstitutive conditions. To our surprise, when incubated with UDP-GlcNAc alone, the protein was found to synthesize chito-oligosaccharide. Taking advantage of these enzyme reaction properties, active sites on the protein involved in for hyaluronan and chito-oligosaccharide synthesis were characterized. Site-directed mutagenesis induced in the cytoplasmic central loop domain of the protein revealed that several amino acid residues conserved among those domains of various proteins of a HAS family were essential for both hyaluronan and chito-oligosaccharide syntheses but one of them was not for chito-oligosaccharide synthesis. The substitutions that caused partial or severe loss of the activity gave no significant changes of the K(m) values of the mutated proteins, suggesting that no conformational or other indirect changes were involved in the effect. Taken together, the results suggest that the HAS1 protein alone is able to synthesize hyaluronan and different amino acid residues on the cytoplasmic central loop domain are involved in transferring GlcNAc and GlcA residues, respectively.

Increased synthesis of hyaluronate enhances motility of human melanoma cells

Hyaluronate plays a unique role in the cancer cell microenvironment. In particular, melanoma is the tumor type in which hyaluronate and hyaluronate recognition have been most closely linked to malignancy. In this study we show that a human melanoma cell line stably transfected with hyaluronate synthase cDNA displays enhanced motility. We used a fixed erythrocyte exclusion assay to isolate subsets of the WM793 human melanoma cell line that expressed either high or low amounts of hyaluronate. A cell line with a high level of hyaluronate on its surface (WM793H) displayed significantly higher cell motility on colloidal-gold-coated coverslips than did a line with a low level (WM793L). Next, in order to directly investigate the effects of hyaluronate on melanoma cell migration, we transfected cDNA encoding mouse hyaluronate synthase HAS1 or HAS2 into the re-cloned human melanoma cell line that produced a low amount of hyaluronate (WM793L) by the lipofection method. Several clonal transfectants differentially producing hyaluronate were obtained. There was a positive correlation between total hyaluronate synthesis and formation of the pericellular hyaluronate-rich matrix. We observed an increase in the migration ability of hyaluronate cDNA (HAS1 or HAS2)-transfected cells compared with control cells on glass plates covered with colloidal gold particles. A migration-inhibition assay with anti-CD44 monoclonal antibody showed blocking of the cell motility. It is speculated that the tumor cells might migrate through a hyaluronate-rich extracellular environment when they invade nearby host tissues and that hyaluronate production by the tumor cells could increase this migration. These results suggest that hyaluronate may play a role in the aggressiveness of human melanoma cells.

Metabolic activities of partially degenerated hypertrophic chondrocytes: gene expression of hyaluronan synthases

Ultrastructural aspects of hypertrophic chondrocytes in hamster and mouse epiphysial cartilage were examined in relation to their metabolic activities. With the hypertrophic change, cytoplasmic vacuolization proceeded leaving the partially intact endoplasmic reticulum (ER). In the hypertrophic cells, cytoplasmic hyaluronan was stained with the biotinylated hyaluronan-binding region (b-HABR) of aggrecan, and mRNAs of hyaluronan synthase (Has 1, Has 2 and Has 3) were detected by in situ hybridization. When the epiphysial cartilage was cultured in the presence of 35S, 3H-GlcNAc, 3H-proline or 14C-palmitic acid, vacuolated late hypertrophic chondrocytes were labeled with these radioactive precursors. The evidence indicates that late hypertrophic chondrocytes are metabolically active, which appears to be essential for the enlargement of chondrocytes.

[Cancer metastasis and extracellular matrix]

We investigated the roles of the extracellular matrix, especially of hyaluronan, in cancer metastasis. A positive relationship was shown between hyaluronan synthetic activity and the metastatic ability of cancer cells by manipulating regulation of gene expression of hyaluronan synthases. These techniques may provide future therapeutic methods for cancer metastasis.

Receptor for hyaluronan-mediated motility and CD44 expressions in colon cancer assessed by quantitative analysis using real-time reverse transcriptase-polymerase chain reaction

Receptor for hyaluronan (HA)-mediated motility (RHAMM) is a receptor for HA-mediated motility and its expression is correlated with malignancy of ras-transformed cells in that binding of HA to this receptor activates their migratory ability. CD44, a cell surface receptor for HA is also implicated in metastatic behavior of some cancer cells. In this study we examined the relationships of cancer progression with mRNA levels of RHAMM, CD44 (all forms), and exon 6 of CD44 using the real-time reverse transcriptase-polymerase chain reaction method in specimens of colon cancers at different diagnostic stages from 30 patients. Increased mRNA levels of RHAMM were observed in 29 specimens (97%), CD44s (all forms) in 21 specimens (70%), and its exon 6 in 19 specimens (63%) in comparison with those in the corresponding noncancerous tissue specimens. A statistically significant correlation between RHAMM expression and cancerous specimens at any of Dukes' stages A, B, and C was found, and the overexpression of CD44 mRNAs was confirmed in specimens at Dukes' stage C. Thus, our present study for the first time suggests that RHAMM expression may be a clinically useful indicator of colon cancer.

Three isoforms of mammalian hyaluronan synthases have distinct enzymatic properties

Three mammalian hyaluronan synthase genes, HAS1, HAS2, and HAS3, have recently been cloned. In this study, we characterized and compared the enzymatic properties of these three HAS proteins. Expression of any of these genes in COS-1 cells or rat 3Y1 fibroblasts yielded de novo formation of a hyaluronan coat. The pericellular coats formed by HAS1 transfectants were significantly smaller than those formed by HAS2 or HAS3 transfectants. Kinetic studies of these enzymes in the membrane fractions isolated from HAS transfectants demonstrated that HAS proteins are distinct from each other in enzyme stability, elongation rate of HA, and apparent K(m) values for the two substrates UDP-GlcNAc and UDP-GlcUA. Analysis of the size distributions of hyaluronan generated in vitro by the recombinant proteins demonstrated that HAS3 synthesized hyaluronan with a molecular mass of 1 x 10(5) to 1 x 10(6) Da, shorter than those synthesized by HAS1 and HAS2 which have molecular masses of 2 x 10(5) to approximately 2 x 10(6) Da. Furthermore, comparisons of hyaluronan secreted into the culture media by stable HAS transfectants showed that HAS1 and HAS3 generated hyaluronan with broad size distributions (molecular masses of 2 x 10(5) to approximately 2 x 10(6) Da), whereas HAS2 generated hyaluronan with a broad but extremely large size (average molecular mass of >2 x 10(6) Da). The occurrence of three HAS isoforms with such distinct enzymatic characteristics may provide the cells with flexibility in the control of hyaluronan biosynthesis and functions.

Preparation of uniformly sized polymeric separation media potentially suitable for small-scale high-performance liquid chromatography and/or capillary electrochromatography

Uniformly sized polymer particles were prepared by either a two-step swelling and polymerization method or a Shirasu porous glass (SPG) emulsification technique to compare their suitability as a uniformly sized packing material for small-scale high-performance liquid chromatography (HPLC) or capillary electrochromatography (CEC). The SPG emulsification technique afforded slightly worse size uniformity compared to the two-step swelling and polymerization technique. However, fairly nice spherical shapes with reproducible outward appearance and internal pore size distribution were obtained for both of 3- or 6-micron sized particles. On the other hand, the two-step swelling and polymerization method afforded broken particles with quite different outward appearances due to the polymeric porogen effects of seed polymer utilized as the shape template. In HPLC, the column packed with the 3-micron particles prepared with the SPG emulsification technique proved to have a fairly high column efficiency with good column stability, as assessed under repeated use in gradient elution. On the other hand, the column packed with the packing material obtained through the two-step swelling and polymerization method showed much poorer column stability, while initial column efficiency was compatible to that obtained using the SPG emulsification method. In addition, the packing material prepared with the SPG emulsification technique could be modified with ion-exchangeable monomers and showed fairly good column efficiency in the CEC mode.

Negative regulation of the pts operon by Mlc: mechanism underlying glucose induction in Escherichia coli

BACKGROUND

The pts operon of Escherichia coli consists of three genes ptsH, ptsI and crr, each encoding for central components of the phosphoenolpyruvate: carbohydrate phosphotransferase system, HPr, enzyme I and IIAGlc, respectively. Transcription of the pts operon is stimulated when glucose is present in the culture medium. One of the two major promoters, P0, is responsible for this glucose induction. However, no regulatory protein responsible for the glucose induction of the pts operon has been identified yet and molecular mechanism by which glucose stimulates the pts transcription is not known.

RESULTS

We found by Northern blotting that the pts mRNA levels in cells lacking Mlc, a new global repressor of carbohydrate metabolism, were increased without external glucose and that the addition of glucose had no effect on the pts mRNA levels in the mutant cells. Western blotting revealed that the enzyme I level in the mlc- cells was also elevated without glucose and no further increase in the enzyme I level was observed in the presence of glucose. S1 analysis revealed that transcription of the glucose-sensitive promoter, P0, occurs constitutively in the mlc- cells independently from the external glucose. In vitro transcription studies indicated that Mlc strongly inhibited P0 transcription. DNase I footprinting experiment revealed that Mlc bound to P0 promoter region to prevent RNA polymerase binding at P0.

CONCLUSION

We conclude that Mlc is a repressor for the pts transcription acting as a major regulatory protein involved in the glucose induction of pts operon. We propose that glucose induces the pts transcription by modulating the Mlc activity. The mechanism by which glucose modulates the Mlc action remains to be studied.

The SHAP-HA complex in sera from patients with rheumatoid arthritis and osteoarthritis

OBJECTIVE

To investigate serum derived hyaluronan (HA) associated protein-hyaluronan (SHAP-HA) complex in sera from patients with rheumatoid arthritis (RA) and osteoarthritis (OA) and determine levels of the complex in comparison with those of hyaluronan (HA), in order to assess the role of the complex as an indicator of joint inflammation.

METHODS

ELISA and HA binding assays were used for quantitation of the SHAP-HA complex and HA levels in serum samples from 142 patients (114 with RA, 28 with OA) and 31 healthy controls. Clinical evaluations were also performed.

RESULTS

In some RA sera, SHAP-HA complex levels were extremely high compared to control levels, but in OA sera no marked increase was observed compared to controls. This was also the case with the HA levels compared between RA and OA sera. However, in RA the levels of the SHAP-HA complex appear to be more related to clinical variables than are levels of HA, and the most significant correlations between levels of SHAP-HA complex and HA were found in the RA group.

CONCLUSION

Quantitation of the SHAP-HA complex in sera may be useful as a joint marker that directly correlates to the degree of joint inflammation in RA, and offers new insight into the pathogenesis of arthritis. It may also serve as an independent criterion in the subsequent classification of RA and OA.

Relationship between hyaluronan production and metastatic potential of mouse mammary carcinoma cells

To investigate the roles of hyaluronan produced by cancer cells in cancer metastasis, the metastatic potential of the highly metastatic mouse mammary carcinoma FM3A HA1 cell line was compared with those of hyaluronan-deficient mutant cells. Five different mutant clones showed markedly reduced hyaluronan production and lacked the ability to form hyaluronan-rich pericellular coats. These mutant clones displayed significant decreases in metastatic ability compared with the parental cells after i.v. injection into syngeneic mice. These results suggested that the decreased hyaluronan production caused not only the lack of matrix formation but also decreased metastatic potential of the cancer cells. Expression of mouse hyaluronan synthase 1 (HAS1) by transfection into HAS- cells defective in hyaluronan synthase activity rescued hyaluronan matrix formation as well as hyaluronan production. Lung metastasis after i.v. injection of HAS1 transfectants was also recovered significantly. The results provide direct evidence for the involvement of hyaluronan in cancer metastasis.

Variable expression of heparan sulfate epitopes in crescents of human glomerulonephritis

Crescentic glomerulonephritis leads to a rapid loss of renal function. Although glomerular crescents are rich in extracellular matrix (ECM), the composition and genesis of the ECM are incompletely understood. Heparan sulfate (HS) is a major ECM molecule and has polymeric structure of great variability. Recent findings that alterations in HS epitopes are associated with renal pathology prompted us to hypothesize that specific HS epitopes might be expressed in the evolution of crescents. We reviewed clinical records of 724 patients who underwent renal biopsy and found 21 patients with rapidly progressive glomerulonephritis. Immunohistochemistry was performed using monoclonal antibodies (mAbs) against well-defined HS epitopes. One mAb was directed against unsaturated uronic acid residues generated during the selective removal of HS by heparitinase (a), and a further two different mAbs against N-sulfate-enriched and O-sulfate-poor portions of HS (b). Results showed that mAb (a) reacted to ECM of normal, sclerosed and crescentic glomeruli and that mAbs (b) reacted strongly to ECM of fibrocellular crescents but not to fibrous crescents, the periglomerular areas and noncrescentic intraglomerular areas. We concluded there are regional differences in HS epitope expression, although HS are ubiquitous components of glomerular ECM. N-sulfate-enriched and O-sulfate-poor portions of HS might play a role in crescent formation.

Immunohistochemical evaluation of the small and large proteoglycans in pleomorphic adenoma of salivary glands

This study investigated the immunolocalization of small and large proteoglycans (PGs), including decorin, biglycan, PG-M/versican and aggrecan, in salivary pleomorphic adenoma (PA) using monoclonal and polyclonal antibodies. In addition, a polyclonal antibody, A0082, recognizing blood vessels was also used to help identify truly mesenchymal tissues in PA. Decorin reactivity was detected only in tumor capsule and interstitial tissue of non-neoplastic salivary gland, but not in the tumor tissue. Biglycan was frequently revealed throughout the matrix of small chondroid regions and in the peripheral portion of larger chondroid regions. PG-M/versican was mainly localized to the truly mesenchymal tissues in PA and the innermost portion of tumor capsule. On the contrary, aggrecan was extensively expressed in the non-luminal epithelial areas as well as in the myxoid and chondroid areas, but not in the truly mesenchymal tissues. These findings suggest that aggrecan is the most widely distributed PG in PA and may be produced mainly by non-luminal tumor cells. The absence of aggrecan from the truly mesenchymal tissues argues against its origin from this source. Both aggrecan and biglycan may play important roles in the chondroid differentiation and morphogenesis of PA.

Solution structure of human acidic fibroblast growth factor and interaction with heparin-derived hexasaccharide

Fibroblast growth factors (FGFs) bind to extracellular matrices, especially heparin-like carbohydrates of heparan-sulfate proteoglycans which stabilize FGFs to protect against inactivation by heat, acid, proteolysis and oxidation. Moreover, binding of FGFs to cell surface proteoglycans promotes to form oligomers, which is essential for receptor oligomerization and activation. In the present study, we determined the solution structure of acidic FGF using a series of triple resonance multi-dimensional NMR experiments and simulated annealing calculations. Furthermore, we prepared the sample complexed with a heparin-derived hexasaccharide which is a minimum unit for aFGF binding. From the chemical shift differences between free aFGF and aFGF-heparin complex, we concluded that the major heparin binding site was located on the regions 110-131 and 17-21. The binding sites are quite similar to those observed for bFGF-heparin hexasaccharide complex, showing that both FGFs recognize heparin-oligosaccharides in a similar manner.

Retention behavior of positional isomers of disubstituted cyclomalto-oligosaccharide (cyclodextrin) derivatives on an ODS column

The correlation between hydrophobic effects and structures of three and four positional isomers of 6(1),6n-di-O-triphenylmethyl (trityl)- or 6(1),6n-di-O-tert.- butyldimethylsilyl (tert.-BuMe2Si)-cyclomaltohexaoses (cG6s, alpha-cyclodextrin) (n = 2-4), -cyclomaltoheptaoses (cG7s, beta-cyclodextrin) (n = 2-4), and -cyclomaltooctaoses (cG8s, gamma-cyclodextrin) (n = 2-5) on an ODS column are discussed. Cyclodextrins with two hydrophobic-substituted groups bonded to hydroxyl groups tended to show low retention of positional isomers in which the binding positions of the two substituted groups on the cyclodextrin ring were far apart from each other.

Roles of aggrecan, a large chondroitin sulfate proteoglycan, in cartilage structure and function

Aggrecan, a large aggregating proteoglycan, is one of the major structural components of cartilage. Its core protein contains three glubular domains and two glycosaminoglycan-attachment domains. These domains play various roles to maintain cartilage structure and function. An N-terminal globular domain binds hyaluronan and link protein to form huge aggregates. The chondroitin sulfate (CS) chains attach to the CS domain and provide a hydrated, viscous gel that absorbs compressive load. Two autosomal recessive chondrodysplasias, cartilage matrix deficiency (cmd) in mice and nanomelia in chicken are both caused by aggrecan gene mutations. Cmd homozygotes die shortly after birth, while the heterozygotes are born normal. However, cmd heterozygotes develop late onset of spinal disorder, which suggests aggrecan as a candidate gene predisposing individuals to spinal problems. Nanomelia is a useful model to elucidate intracellular trafficking of proteoglycans. Further studies on aggrecan will lead to prophylaxis and treatment of joint destructive diseases such as osteoarthrosis and to elucidation of cartilage development, which is essential for skeletal formation.

A global repressor (Mlc) is involved in glucose induction of the ptsG gene encoding major glucose transporter in Escherichia coli

Glucose stimulates the expression of ptsG encoding the major glucose transporter in Escherichia coli. We isolated Tn 10 insertion mutations that confer constitutive expression of ptsG. The mutated gene was identified as mlc, encoding a protein that is known to be a repressor for transcription of several genes involved in carbohydrate utilization. Expression of ptsG was eliminated in a mlc crp double-negative mutant. The Mlc protein was overproduced and purified. In vitro transcription studies demonstrated that transcription of ptsG is stimulated by CRP-cAMP and repressed by Mlc. The action of Mlc is dominant over that of CRP-cAMP. DNase I footprinting experiments revealed that CRP-cAMP binds at two sites centred at -40.5 and -95.5 and that Mlc binds at two regions centred around -8 and -175. The binding of CRP-cAMP stimulated the binding of RNA polymerase to the promoter while Mlc inhibited the binding of RNA polymerase but not the binding of CRP-cAMP. Gel-mobility shift assay indicated that glucose does not affect the Mlc binding to the ptsG promoter. Our results suggest that Mlc is responsible for the repression of ptsG transcription and that glucose modulates the Mlc activity by unknown mechanism.

Effects of compositions of dimethyl-beta-cyclodextrins on enantiomer separations by cyclodextrin modified capillary zone electrophoresis

In enantiomeric separation by capillary zone electrophoresis using dimethyl-beta-cyclodextrin (DM-beta-CD) as a chiral selector, enantioselectivities were sometimes significantly different among DM-beta-CDs from five different suppliers. The reason was due to the difference in the compositions among these commercial products, which was shown by the liquid chromatographic (LC) analysis. As for commercial DM-beta-CD from one supplier, two major components were obtained by preparative LC. NMR spectroscopic and mass spectrometric analyses of these two components were performed to estimate the structure of each component. The results implied that the commercial products consist of heptakis(2,6-di-O-dimethyl)-beta-CD and hexakis(2,6-di-O-methyl)-mono(2,3,6-tri-O-methyl)-beta-CD. Sometimes different enantioselectivities were observed between these two components including the original DM-beta-CD.

Molecular cloning and expression of human chondroitin 6-sulfotransferase

Using cDNA of chick chondroitin 6-sulfotransferase (C6ST), human C6ST cDNA has been isolated. The amino acid sequence of human C6ST displayed 74% identity to chick C6ST. The major difference in amino acid sequence between chick C6ST and human C6ST was the presence of a unique hydrophilic domain in human C6ST. A 7.8-kb message of C6ST was expressed ubiquitously in various human adult tissues, indicating a rather diverse function of C6ST.