Hyaluronidase assay using fluorogenic hyaluronate as a substrate

Direct detection of hyaluronidase in urine using cationic gold nanoparticles: a potential diagnostic test for bladder cancer

Hyaluronidase (HAase) was reported as a urinary marker of bladder cancer. In this study, a simple colorimetric gold nanoparticle (AuNP) assay was developed for rapid and sensitive detection of urinary HAase activity. Charge interaction between polyanionic hyaluronic acid (HA) and cationic AuNPs stabilized with cetyl trimethyl ammonium bromide (CTAB) led to formation of gold aggregates and a red to blue color shift. HAase digests HA into small fragments preventing the aggregation of cationic AuNPs. The nonspecific aggregation of AuNPs in urine samples was overcome by pre-treatment of samples with the polycationic chitosan that was able to agglomerate all negatively charged interfering moieties before performing the assay. The developed AuNP assay was compared with zymography for qualitative detection of urinary HAase activity in 40 bladder carcinoma patients, 11 benign bladder lesions patients and 15 normal individuals, the assay sensitivity was 82.5% vs. 65% for zymography, while the specificity for both assays was 96.1%. The absorption ratio, A530/A620 of the reacted AuNP solution was used to quantify the HAase activity. The best cut off value was 93.5 μU/ng protein, at which the sensitivity was 90% and the specificity was 80.8%.The developed colorimetric AuNP HAase assay is simple, inexpensive, and can aid noninvasive diagnosis of bladder cancer.

Synthesis of neoproteoglycans using the transglycosylation reaction as a reverse reaction of endo-glycosidases

A method for the synthesis of carbohydrate chains (glycosaminoglycans) and their coupling to peptides was investigated using proteoglycans. Glycosidases generally catalyze a hydrolytic reaction, but can also mediate the reverse reaction, which in this case is a transglycosylation. In the transglycosylation reaction of bovine testicular hyaluronidase, which is an endoglycosidase, glycosaminoglycans (hyaluronan and chondroitin sulfates) release disaccharide (uronic acid-N-acetylhexosamine) moieties from non-reducing terminal sites, and then the liberated disaccharides are transferred immediately to the non-reducing termini of other glycosaminoglycan chains. Using such continuous reactions, it is possible to synthesize glycosaminoglycan chains according to a specific design. It then becomes possible to transfer glycosaminoglycan chains synthesized on a peptide to other peptides using the transglycosylation reaction of endo-β-xylosidase acting on the linkage region between a peptide and glycosaminoglycan chains of proteoglycans. We believe this approach will open a new field for the synthesis of homogeneous proteoglycans or their corresponding analogues.

A simple assay for hyaluronidase activity using fluorescence polarization

Hyaluronan is a large glycosaminoglycan and is a major constituent of the extracellular matrix, interacting with cell surface receptors such as CD44. We previously reported that fragmented hyaluronan, with the size frequently detected in cancer patients, induces CD44 cleavage and concomitantly enhances tumor cell migration. Although hyaluronan degradation to smaller fragments has been revealed to be a key reaction in regulating cancer progression, simple methods for continuously detecting hyaluronidase activity have not been established. Here, we show that fluorescently-labeled hyaluronan serves as a substrate for continuous assay of hyaluronidase activity. A very simple assay was established to measure degradation of hyaluronan based on fluorescence polarization. The developed assay method would provide a way for continuous measurement of cellular hyaluronidase activity and also for measurement of binding of hyaluronan to its receptors, and thus should be useful for investigation of the function of hyaluronan in cancer progression.

New potent indole derivatives as hyaluronidase inhibitors

Because of the physiologic importance of hyaluronidases, the identification of potent and selective inhibitors of hyaluronidases has become increasingly important. A variety of assay methods have been used for such a purpose, i.e. classical turbidimetric, viscometric and colorimetric. In this study, a modified enzymatic assay has been used to obtain a microtiter plate-based sensitive activity screening. All inhibitors were tested in a stains-all assay at pH 7 and in a Morgan-Elson assay at pH 3.5. Among the tested compounds, 1, 2, 3, 6, 7, 8, 16, 17 and 18 showed good inhibition of more than 50%, so the IC(50) values of these derivatives were determined in the range of 25-41 microm. The IC(50) value of the most active hyaluronidase inhibitor Vcpal (6-palmitoyl-L-ascorbic acid) was measured as 8.36 microm. All inhibitors including Vcpal showed twofold less activity at pH 3.5 in a Morgan-Elson assay. Examination of substituent effects on the activity showed that para-positions of benzamide needs to be chlorinated or fluorinated to obtain good inhibitory effect. It was found that the introduction of a p-fluoro benzyl ring in the indole nitrogen has a positive effect for the inhibitory effects of both indole-2- and 3-carboxamide derivatives.

Development of highly sensitive fluorescent assays for fatty acid amide hydrolase

Fatty acid amide hydrolase (FAAH) is a pharmaceutical target whose inhibition may lead to valuable therapeutics. Sensitive substrates for high-throughput assays are crucial for the rapid-screening FAAH inhibitors. Here we describe the development of novel and highly sensitive fluorescent assays for FAAH based on substituted aminopyridines. Examining the relationship between the structure and the fluorescence of substituted aminopyridines suggested that a methoxy group in the para position relative to the amino group in aminopyridines greatly increased the fluorescence (i.e., quantum yields approach unity). These novel fluorescent reporters had a high Stokes' shift of 94 nm, and their fluorescence in buffer systems increased with pH values from neutral to basic. Fluorescent substrates with these reporters displayed a very low fluorescent background and high aqueous solubility. Most importantly, fluorescent assays for FAAH based on these substrates were at least 25 times more sensitive than assays using related compounds with published colorimetric or fluorescent reporters. This property results in shorter assay times and decreased protein concentrations in the assays. Such sensitive assays will facilitate distinguishing the relative potency of powerful inhibitors of FAAH. When these fluorescent substrates were applied to human liver microsomes, results suggested that there was at least one amide hydrolase in addition to FAAH that could hydrolyze long-chain fatty acid amides. These results show that these fluorescent substrates are very valuable tools in FAAH activity assays including screening inhibitors by high-throughput assays instead of using the costly and labor-intensive radioactive ligands. Potential applications of novel fluorescent reporters are discussed.

A fluorimetric Morgan–Elson assay method for hyaluronidase activity

Despite their physiological importance, hyaluronidases (HAases) have long been "neglected enzymes," due, presumably, in part to the lack of rapid, sensitive assays. Currently, the colorimetric Morgan-Elson assay method, which is based upon the generation of a new reducing N-acetyl-D-glucosamine terminus with each cleavage reaction, is most widely employed but is yet insensitive. We, therefore, reinvestigated the colorimetric method and established the fluorimetric Morgan-Elson assay for HAase activity, with the optimized tetraborate reagent. The fluorimetric assay, requiring neither specialized reagents nor a long time to perform, provided high sensitivity, nearly comparable to that of enzyme-linked immunosorbent assay (ELISA)-like assays, with a detection limit of 5 x 10(-3)NFU/ml of bovine testicular HAase after 1-h incubation. The increased sensitivity permitted rapid measurement of low HAase activity in biological samples such as human and rabbit serum HAases, the latter of which has not been detected either by an ELISA-like assay or by zymography. Human serum HAase was easily characterized it along with its optimum pH and kinetic parameters.

Changes in glycosaminoglycan, galactosyltransferase-I, and sialyltransferase during rat liver regeneration

After partial hepatectomy, the liver is capable of complete restoration to its normal size. The extracellular matrix, which surrounds the cells, plays important roles in this regeneration. Glycosaminoglycans (GAGs), which are components of the extracellular matrix, interact with several other matrix components and growth factors, and are involved in hepatocyte growth. In this study, the content of heparan sulfate, a major GAG in rat liver, reached a minimum at 12 hours after partial hepatectomy. Galactosyltransferase-I activity, related to the synthesis of GAGs, and sialyltransferase activity, related to the synthesis of glycoconjugates, reached a minimum at 6 hours. The serum and liver contents of hyaluronic acid reached a maximum at 1 day and returned gradually to their preoperative levels. These results suggest that polysaccharide synthesis was decreased in the Golgi apparatus of hepatocytes at the beginning of regeneration, and that hyaluronic acid degradation decreased in the lysosomes of hepatocytes. The ability to synthesize polysaccharides recovered ahead of the ability to degrade hyaluronic acid. The changes in these GAGs with time in the early regeneration period might play an important role in organ regeneration.

Quantitation of hyaluronidases by the Morgan-Elson reaction: comparison of the enzyme activities in the plasma of tumor patients and healthy volunteers

The Morgan-Elson reaction, a method for the determination of hyaluronidase activity, was optimized for the quantitation of the enzyme in biological material. Based on HPLC and spectrometric (UV-Vis, LC-MS) studies, the structure of the red-colored product (mesomeric forms of N3-protonated 3-acetylimino-2-(4-dimethylaminophenyl)methylidene-5-(1,2-++ +dihydroxyethyl)furane) formed by condensation of chromogen III with p-dimethylaminobenzaldehyde is proposed. Activities corresponding to > or = 0.1 IU of endogenous and therapeutically administered hyaluronidase can be detected in 50 microl samples. Application of the method for the determination of the enzyme in plasma of tumor patients revealed no difference in activity levels, interindividual variability and pH profile compared to healthy volunteers.

Ion-spray mass spectrometry for identification of the nonreducing terminal sugar of glycosaminoglycan

Various oligosaccharides from hyaluronic acid, which have glucuronic acid or N- acetylglucosamine at the nonreducing terminal, were prepared by digestion with a combination of testicular hyaluronidase and beta-glucuronidase. These oligo saccharides were analyzed by negative-mode ion-spray mass spectrometry (MS) with an atmospheric pressure ion source. Introduction of collisionally activated dissociation tandem mass spectrometry (CAD-MS/MS) produced ions derived from cleavage of the glycosidic bonds, allowing the structure to be analyzed. The CAD-MS/MS spectrum showed an intense and characteristic fragment ion at m/z 193 for oligosaccharides having glucuronic acid at the nonreducing terminal. On the other hand, this ion was not observed in the spectra of oligosaccharides having N- acetylglucosamine at the nonreducing terminal. Therefore, the fragmentation pattern revealed by CAD-MS/MS provides useful information for distinguishing glucuronic acid and N- acetylglucosamine at the nonreducing terminal of oligosaccharides derived from hyaluronic acid and other glycosaminoglycans. This ion-spray CAD-MS/MS technique was also applied successfully to the characterization of glycosaminoglycans reconstructed by glycotechnology.

Characterization of glycosaminoglycans in regenerating canine liver

BACKGROUND/AIMS

Liver regeneration after partial hepatectomy is accompanied by hepatocyte proliferation and alteration of the extracellular matrix. Glycosaminoglycans, which are components of the extracellular matrix, interact with other matrix components, and are related to hepatocyte growth. The aim of this study was to investigate the relationship between hepatocyte proliferation and changes in glycosaminoglycan.

METHODS

Hepatocyte proliferation and changes in glycosaminoglycan were investigated in dogs after 55% partial hepatectomy. Hepatocyte mitosis was investigated by immunohistochemistry using anti-proliferating cell nuclear antigen antibody. The amount of glycosaminoglycan was determined by the carbazole-sulfuric acid method. We used a new method for analysis of glycosaminoglycan chains, involving endo-beta-xylosidase digestion and fluorescence labelling, to investigate the components of glycosaminoglycan.

RESULTS

Hepatocyte mitosis was increased after hepatectomy, reaching a peak at postoperative day 7. The total amount of hepatic glycosaminoglycan reached a maximum at 1 to 2 weeks afer hepatectomy, and the ratio of the components showed a concomitant change, the amount of heparan sulfate increasing, and that of chondroitin sulfate/dermatan sulfate decreasing. Increased heparan sulfate has shorter chains at 1 to 2 weeks after hepatectomy.

CONCLUSIONS

These results suggest that the transient changes in heparan sulfate with a decreased chain length and chondroitin sulfate/dermatan sulfate and observed during liver regeneration are associated with hepatocyte proliferation.

Enzymic reconstruction of glycosaminoglycan oligosaccharide chains using the transglycosylation reaction of bovine testicular hyaluronidase

The reconstruction of glycosaminoglycan chains using the transglycosylation reaction of testicular hyaluronidase was investigated. First, the optimal conditions for the transglycosylation reaction catalyzed by the enzyme were determined by incubation with the enzyme, using hyaluronic acid (M(r) = 800,000) as a donor and pyridylaminated hyaluronic acid hexasaccharide having glucuronic acid at the nonreducing terminal as an acceptor. The carbohydrate chains as reaction products were determined by high performance liquid chromatography and mass spectrometry. The optimal pH for hydrolysis by the enzyme was found to be about 5.0, whereas that for the transglycosylation reaction was about 7.0. Sodium chloride in the reaction medium inhibited the transglycosylation reaction. Under the optimal conditions, the carbohydrate chains were sequentially transferred along with disaccharide units to the nonreducing terminal of the acceptor and elongated up to docosasaccharide from the acceptor, pyridylaminated hexasaccharide. Using a combination of hyaluronic acid, chondroitin, and chondroitin 4- and 6-sulfate as an acceptor and a donor, it was possible to reconstruct hybrid chains, which were natural or unnatural types of glycosaminoglycan chains. Therefore, it is highly likely that application of the transglycosylation reaction using testicular hyaluronidase would facilitate artificial reconstruction of glycosaminoglycans having some physiological functions.

Hyaluronate depolymerization activity induced by progesterone in cultured fibroblasts derived from human uterine cervix

High-molecular-weight [14C]hyaluronate was incubated with cultured fibroblasts from human uterine cervix and skin, and then the depolymerization of the hyaluronate was investigated. [14C]Hyaluronate in the medium of skin fibroblasts was depolymerized into a constant molecular weight (M(r) about 40,000), whereas that of cervix fibroblasts was not depolymerized, irrespective of incubation period. However, when progesterone was added to the medium of cervix fibroblasts, hyaluronate was depolymerized to the same extent as that in skin fibroblasts. The reducing terminal sugar of the depolymerized hyaluronate was N-acetylglucosamine. These results suggest that a hyaluronate-depolymerizing enzyme, endo-beta-N-acetylglucosaminidase, was induced by progesterone in cultured fibroblasts derived from human uterine cervix.

Analysis of glycosaminoglycans by high-performance liquid chromatography

Glycosaminoglycan chains were liberated from proteoglycan by successive digestion with protease and endo-beta-xylosidase. The glycosaminoglycan chains were then labeled with a fluorescent reagent, 2-aminopyridine, by reductive amination. The resulting pyridylamino-glycosaminoglycans, including hyaluronic acid, heparan sulfate, chondroitin sulfate/dermatan sulfate and heparin, were separated by ion-exchange high-performance liquid chromatography using a TSK gel SAX analytical column with a limit of sensitivity in the picomol range. With the combined use of a dermatan sulfate-degrading enzyme, chondroitinase B, chondroitin sulfate and dermatan sulfate were identified and quantified, separately. About 50 mg of wet animal tissue was enough for analysis of each glycosaminoglycan with satisfactory results. This method facilitates rapid separation and microanalysis of glycosaminoglycans.

Partial purification and characterization of an endo-alpha-N-acetylgalactosaminidase from the culture medium of Streptomyces sp. OH-11242

For the purification of a new type of endo-alpha-N-acetylgalactosaminidase from the culture medium of Streptomyces sp. OH-11242 (endo-GalNAc-ase-S) [Iwase, Ishii, Ishihara, Tanaka, Omura & Hotta (1988) Biochem. Biophys. Res. Commun. 151, 422-428], a method for assaying enzyme activity was established. Using purified pig gastric mucus glycoprotein (PGM) as the substrate, oligosaccharides liberated from PGM were pyridylaminated, and the reducing terminal sugars of oligosaccharides larger than Gal beta 1-3GalNAc were analysed by h.p.1.c. The crude enzyme of endo-GalNAc-ase-S was prepared as an 80% (w/v) ammonium sulphate precipitate from the concentrated culture medium. The enzyme was partially purified by gel chromatofocusing and subsequent DEAE-Toyopearl chromatography. Endo-enzyme activity eluted around pI 4.8 on a gel chromatofocusing column and eluted with 0.19-0.25 M-NaCl on a DEAE-Toyopearl column. In the enzyme fraction obtained, no exo-glycosidases or proteases could be detected. The molecular mass of the enzyme was estimated as 105 kDa by gel filtration, and the optimum pH was 5.5. Endo-GalNAc-ase-S hydrolysed the O-glycosidic linkage between GalNAc and Ser (Thr) in 3H-labelled and unlabelled asialofetuin, liberating both the disaccharide (Gal beta 1-3GalNAc) and the tetrasaccharide [Gal beta 1-3 (Gal beta 1-4GlcNAc beta 1-6)GalNAc]. When endo-alpha-N-acetylgalactosaminidase from Alcaligenes sp. (endo-GalNac-ase-A) was incubated with 3H-labelled and unlabelled asialofetuin, only the disaccharide (Gal beta 1-3GalNAc) was liberated.

An ELISA-like assay for hyaluronidase and hyaluronidase inhibitors

Hyaluronic acid (HA) is a prominent molecule in the extracellular matrix and is enriched whenever there is rapid tissue proliferation, regeneration and repair. HA is degraded in part by hyaluronidases (HA'ases) that are not well characterized. We have developed a novel ELISA-like rapid assay for HA'ases and their inhibitors. The assay is based on a high affinity biotinylated HA-binding peptide derived from tryptic digests of proteoglycan core protein of bovine nasal cartilage and the avidin-biotin reaction. HA-coated plates were incubated with serial dilutions of Streptomyces HA'ase, and the undegraded HA was measured. This established a standard curve for HA'ase activity against which all unknown enzyme samples were compared. The assay is easily modified to also serve a measure of HA'ase inhibitors. For detection of inhibitors, aliquots of sample were preincubated with a known activity of HA'ase and inhibition of HA degradation by the mixture was measured. We have used this assay to document the presence of potent HA'ase inhibitors in fetal calf sera. These techniques will aid in the purification and characterization of Ha'ases and their inhibitors.

A substrate-gel assay for hyaluronidase activity

Hyaluronic acid (HA) is a key structural element of the extracellular matrix. Turnover rates of HA are determined in part by hyaluronidases, that are themselves modulated by hyaluronidase inhibitors. A substrate polyacrylamide gel electrophoresis procedure is described here that separates enzyme from inhibitors. The HA is embedded in the gel, and following electrophoretic separation, enzymatic digestion of the HA is allowed to occur. The gel is stained with Alcian blue and can be secondarily stained with Coomassie blue. Enzymatic activities appear as cleared bands on a light blue background, while major proteins appear as dark blue bands. The procedure can be performed in the presence or absence of sodium dodecylsulfate, though levels of hyaluronidase activity decrease when the detergent is used. Hyaluronidases active in the neutral or acid pH range can be detected. This technique will facilitate characterization of hyaluronidases and inhibitors from a wide variety of sources.

Ion-spray mass spectrometric analysis of glycosaminoglycan oligosaccharides

Oligosaccharides from hyaluronic acid and chondroitin 6-sulfate were prepared by digestion with testicular hyaluronidase and separated according to their degree of polymerization by gel-permeation chromatography. These materials were successively analyzed by negative-mode ion-spray mass spectrometry with an atmospheric-pressure ion source. An ion-spray interface was used to produce ions via the ion evaporation process, producing mass spectra containing a series of molecular species carrying multiple charges. Using two adjacent multiply charged molecular ions, the exact molecular weights up to the tetradecasaccharide were calculated with a precision of +/- 1 dalton. This type of mass spectrometry was also demonstrated to be feasible for the analysis of mixtures of oligosaccharides, including tetra-, hexa-, octa- and decasaccharides, from hyaluronic acid or chondroitin 6-sulfate without separation. Ion-spray mass spectrometry was thus shown to be applicable to the structural analysis of oligosaccharides from glycosaminoglycans.

Hyaluronate synthesized by cultured skin fibroblasts derived from patients with Werner's syndrome

Hyaluronate in cultured skin fibroblasts derived from patients with Werner's syndrome, who excrete large amounts of urinary hyaluronate, was investigated. The amount of hyaluronate secreted into the medium by Werner's fibroblasts was 2-3-times that of normal fibroblasts, whereas no difference in enzyme activities related to the degradation of hyaluronate was found. Werner's fibroblasts were then cultured in the presence of [3H]glucosamine, and the amount of [3H]hyaluronate and its chain lengths in the medium and matrix (trypsinate) fractions were compared with those of normal cells. No significant difference in the chain length of hyaluronate was observed between normal and Werner's fibroblasts. On the other hand, a significant increase of hyaluronate was found in the matrix fraction of Werner's fibroblasts when the cells reached confluency. In addition, a hyaluronate of small chain length was found in the matrix fraction of Werner's fibroblasts, although this was absent from that of normal cells. It was concluded that the constituents of the extracellular matrix of Werner's fibroblasts differed from those of normal cells, characterized by the presence of a large amount of hyaluronate and a relatively small hyaluronate chain.