Characterization of hydrolysis and transglycosylation by testicular hyaluronidase using ion-spray mass spectrometry

Enzymatic Production of Low-Molecular-Weight Hyaluronan and Its Oligosaccharides: A Review and Prospects

Hyaluronic acid (HA) is a nonsulfated linear glycosaminoglycan with a negative charge. Different from the high-molecular-weight HAs, the low-molecular-weight HAs (LMW-HAs, 4-120 kDa) and hyaluronan oligosaccharides (O-HAs, <4 kDa) exhibit certain unique biological properties, owing to which these have a wide range of applications in the field of medicine. However, the chemical synthesis of high-purity LMW-HAs and O-HAs requires complex procedures, which renders this process difficult to achieve. The degradation of HA is achieved under the catalysis of hyaluronidases. In recent years, various hyaluronidase genes have been identified, and their enzymatic properties have been analyzed. In this context, the present review summarizes the hyaluronidases from different sources, which have been characterized. The review focuses on the crystal structure and the catalytic mechanism underlying the biological properties of hyaluronidases. In addition, the molecular weight distributions and the preparation approaches of the enzymatic products LMW-HAs and O-HAs are described. The general orientation of the research on hyaluronidases was speculated based on the existing literature. Accordingly, the efficient large-scale production of LMW-HAs and O-HAs using the green enzymatic approach was anticipated.

Active Expression of Human Hyaluronidase PH20 and Characterization of Its Hydrolysis Pattern

Hyaluronidases are a group of glycosidases catalyzing the degradation of hyaluronic acid (HA). Because of the advantages of effectively hydrolyzing the HA-rich matrix and low immunogenicity, human hyaluronidase PH20 (hPH20) is widely used in the medical field. Here, we realized the active expression of recombinant hPH20 by Pichia pastoris under a methanol-induced promoter PAOX1. By optimizing the composition of the C-terminal domain and fusing protein tags, we constructed a fusion mutant AP2-△491C with the extracellular hyaluronidase activity of 258.1 U·L-1 in a 3-L bioreactor, the highest expression level of recombinant hPH20 produced by microbes. Furthermore, we found recombinant hPH20 hydrolyzed the β-1,4 glycosidic bonds sequentially from the reducing end of o-HAs, with HA6 NA as the smallest substrate. The result will provide important theoretical guidance for the directed evolution of the enzyme to prepare multifunctional o-HAs with specific molecular weights.

Matters of size: Roles of hyaluronan in CNS aging and disease

Involvement of extracellular matrix (ECM) components in aging and age-related neurodegeneration is not well understood. The role of hyaluronan (HA), a major extracellular matrix glycosaminoglycan, in malignancy and inflammation is gaining new understanding. In particular, the differential biological effects of high molecular weight (HMW-HA) and low molecular weight hyaluronan (LMW-HA), and the mechanism behind such differences are being uncovered. Tightly regulated in the brain, HA can have diverse effects on cellular development, growth and degeneration. In this review, we summarize the homeostasis and signaling of HA in healthy tissue, discuss its distribution and ontogeny in the central nervous system (CNS), summarize evidence for its involvement in age-related neurodegeneration and Alzheimer Disease (AD), and assess the potential of HA as a therapeutic target in the CNS.

Mammal Hyaluronidase Activity on Chondroitin Sulfate and Dermatan Sulfate: Mass Spectrometry Analysis of Oligosaccharide Products

Mammalian hyaluronidases are endo-N-acetyl-D-hexosaminidases involved in the catabolism of hyaluronic acid (HA) but their role in the catabolism of chondroitin sulfate (CS) is also examined. HA and CS are glycosaminoglycans (GAGs) implicated in several physiological and pathological processes, and understanding their metabolism is of significant importance. Data have been previously reported on the degradation of CS under the action of hyaluronidase, yet a detailed structural investigation of CS depolymerization products remains necessary to improve our knowledge of the CS depolymerizyng activity of hyaluronidase. For that purpose, the fine structural characterization of CS oligosaccharides formed upon the enzymatic depolymerization of various CS sub-types by hyaluronidase has been carried out by high resolution Orbitrap mass spectrometry and extreme UV (XUV) photodissociation tandem mass spectrometry. The exact mass measurements show the formation of wide size range of even oligosaccharides upon digestion of CS-A and CS-C comprising hexa- and octa-saccharides among the main digestion products, as well as formation of small quantities of odd-numbered oligosaccharides, while no hyaluronidase activity was detected on CS-B. In addition, slight differences have been observed in the distribution of oligosaccharides in the digestion mixture of CS-A and CS-C, the contribution of longer oligosaccharides being significantly higher for CS-C. The sequence of CS oligosaccharide products determined XUV photodissociation experiments verifies the selective β(1 → 4) glycosidic bond cleavage catalyzed by mammal hyaluronidase. The ability of the mammal hyaluronidase to produce hexa- and higher oligosaccharides supports its role in the catabolism of CS anchored to membrane proteoglycans and in extra-cellular matrix.

Essential hyaluronan structure for binding with hyaluronan-binding protein (HABP) determined by glycotechnological approach

Hyaluronan specifically binds to aggrecan globular domain 1, which is often referred to as just hyaluronan binding protein (HABP), however, the hyaluronan carbohydrate structure recognized by HABP had not been studied in detail. The aim of the present study was to investigate the important structure of hyaluronan for binding to HABP. We prepared hybrid oligosaccharides from hyaluronan and chondroitin, with or without modification of the reducing or non-reducing terminus, as tools to determine the preferred structure of hyaluronan for binding to the HABP by a competitive ELISA-like method. The non-reducing terminal structure was critical, especially, the glucuronic acid (GlcUA) and N-acetylglucosamine (GlcNAc) of the hyaluronan-unit are essential for complete HABP binding activity, and for any HABP binding activity, respectively. It is possible to replace GlcUAβ-1-3GlcNAc of the internal disaccharide units with GlcUAβ-1-3N-acetylgalactosamine (GalNAc), if the chain length is decasaccharide or larger.

Endoglycosidases for the Synthesis of Polysaccharides and Glycoconjugates

Recent advances in glycobiology have implicated essential roles of oligosaccharides and glycoconjugates in many important biological recognition processes, including intracellular signaling, cell adhesion, cell differentiation, cancer progression, host-pathogen interactions, and immune responses. A detailed understanding of the biological functions, as well as the development of carbohydrate-based therapeutics, often requires structurally well-defined oligosaccharides and glycoconjugates, which are usually difficult to isolate in pure form from natural sources. To meet with this urgent need, chemical and chemoenzymatic synthesis has become increasingly important as the major means to provide homogeneous compounds for functional glycocomics studies and for drug/vaccine development. Chemoenzymatic synthesis, an approach that combines chemical synthesis and enzymatic manipulations, is often the method of choice for constructing complex oligosaccharides and glycoconjugates that are otherwise difficult to achieve by purely chemical synthesis. Among these, endoglycosidases, a class of glycosidases that hydrolyze internal glycosidic bonds in glycoconjugates and polysaccharides, are emerging as a very attractive class of enzymes for synthetic purposes, due to their transglycosylation activity and their capability of transferring oligosaccharide units en bloc in a single step, in contrast to the limitation of monosaccharide transfers by common glycosyltransferases. In this chapter, we provide an overview on the application of endoglycosidases for the synthesis of complex carbohydrates, including oligosaccharides, polysaccharides, glycoproteins, glycolipids, proteoglycans, and other biologically relevant polysaccharides. The scope, limitation, and future directions of endoglycosidase-catalyzed synthesis are discussed.

Inhibitory effect of chondroitin sulfate oligosaccharides on bovine testicular hyaluronidase

Hyaluronan and chondroitin sulfates are prominent components of the extracellular matrices of animal tissues; however, their functions in relation to their oligosaccharide structures have not yet been fully elucidated. The oligosaccharides of hyaluronan and chondroitin sulfate were prepared and used to investigate their effects on the hydrolysis and transglycosylation reactions of bovine testicular hyaluronidase when hyaluronan was used as a substrate. Hydrolysis and transglycosylation activities were assessed in independent reaction systems by analyzing the products by HPLC. The hydrolysis and transglycosylation reactions of bovine testicular hyaluronidase were dose-dependently inhibited by chondroitin sulfate oligosaccharides, but not by hyaluronan or chondroitin oligosaccharides. A kinetic analysis of the hydrolysis reaction using hyaluronan octasaccharide revealed that the inhibition mode by chondroitin sulfate oligosaccharides was competitive.

A new affinity method for purification of bovine testicular hyaluronidase enzyme and an investigation of the effects of some compounds on this enzyme

In this study, a new affinity gel for the purification of bovine testicular hyaluronidase (BTH) was synthesized. L-Tyrosine was added as the extension arm to the Sepharose-4B activated with cyanogen bromide. m-Anisidine is a specific inhibitor of BTH enzyme. m-Anisidine was clamped to the newly formed Sepharose-4B-L-tyrosine as a ligand. As a result, an affinity gel having the chemical structure of Sepharose-4B-L-tyrosine-m-anisidine was obtained. BTH purified by ammonium sulfate precipitation and affinity chromatography was obtained with a 16.95% yield and 881.78 degree of purity. The kinetic constants K(M) and V(Max) for BTH were determined by using hyaluronic acid as a substrate. K(M) and V(Max) values obtained from the Lineweaver-Burk graph were found to be 2.23 mM and 19.85 U/mL, respectively. In vitro effects of some chemicals were determined on purified BTH enzyme. Some chemically active ingredients were 1,1-dimethyl piperidinium chloride, β-naphthoxyacetic acid and gibberellic acid. Gibberellic acid showed the best inhibition effect on BTH.

Hyaluronan-chondroitin hybrid oligosaccharides as new life science research tools

Hyaluronan and chondroitin are glycosaminoglycans well-known as components of pharmaceutical agents and health foods. From these attractive molecules, using transglycosylation reaction of testicular hyaluronidase, we synthesized hybrid neo-oligosaccharides not found in nature. We also found a new site between the chondroitin disaccharide unit and hyaluronan disaccharide unit recognized by a hyaluronan lyase specific to hyaluronan using these hybrid oligosaccharides as substrates. We hope that these hybrid oligosaccharides will help to elucidate the involvement of hyaluronan, chondroitin, and chondroitin sulfates in the mechanisms of cell functions and diseases, based on the structures of these glycosaminoglycans.

Exploiting enzyme specificities in digestions of chondroitin sulfates A and C: production of well-defined hexasaccharides

Interactions between proteins and glycosaminoglycans (GAGs) of the extracellular matrix are important to the regulation of cellular processes including growth, differentiation and migration. Understanding these processes can benefit greatly from the study of protein-GAG interactions using GAG oligosaccharides of well-defined structure. Materials for such studies have, however, been difficult to obtain because of challenges in synthetic approaches and the extreme structural heterogeneity in GAG polymers. Here, it is demonstrated that diversity in structures of oligosaccharides derived by limited enzymatic digestion of materials from natural sources can be greatly curtailed by a proper selection of combinations of source materials and digestive enzymes, a process aided by an improved understanding of the specificities of certain commercial preparations of hydrolases and lyases. Separation of well-defined oligosaccharides can then be accomplished by size-exclusion chromatography followed by strong anion-exchange chromatography. We focus here on two types of chondroitin sulfate (CS) as starting material (CS-A, and CS-C) and the use of three digestive enzymes with varying specificities (testicular hyaluronidase and bacterial chondroitinases ABC and C). Analysis using nuclear magnetic resonance and mass spectrometry focuses on isolated CS disaccharides and hexasaccharides. In all, 15 CS hexasaccharides have been isolated and characterized. These serve as useful contributions to growing libraries of well-defined GAG oligosaccharides that can be used in further biophysical assays.

Structural interactions in chondroitin 4-sulfate mediated adherence of Plasmodium falciparum infected erythrocytes in human placenta during pregnancy-associated malaria

Infection with Plasmodium falciparum during pregnancy results in the adherence of infected red blood cells (IRBCs) in placenta, causing pregnancy-associated malaria with severe health complications in mothers and fetuses. The chondroitin 4-sulfate (C4S) chains of very low sulfated chondroitin sulfate proteoglycans (CSPGs) in placenta mediate the IRBC adherence. While it is known that partially sulfated but not fully sulfated C4S effectively binds IRBCs, structural interactions involved remain unclear and are incompletely understood. In this study, structurally defined C4S oligosaccharides of varying sulfate contents and sizes were evaluated for their ability to inhibit the binding of IRBCs from different P. falciparum strains to CSPG purified from placenta. The results clearly show that, with all parasite strains studied, dodecasaccharide is the minimal chain length required for the efficient adherence of IRBCs to CSPG and two 4-sulfated disaccharides within this minimal structural motif are sufficient for maximal binding. Together, these data demonstrate for the first time that the C4S structural requirement for IRBC adherence is parasite strain-independent. We also show that the carboxyl group on nonreducing end glucuronic acid in dodecasaccharide motif is important for IRBC binding. Thus, in oligosaccharides containing terminal 4,5-unsaturated glucuronic acid, the nonreducing end disaccharide moiety does not interact with IRBCs due to the altered spatial orientation of carboxyl group. In such C4S oligosaccharides, 14-mer but not 12-mer constitutes the minimal motif for inhibition of IRBC binding to placental CSPG. These data have important implications for the development and evaluation of therapeutics and vaccine for placental malaria.

On-line separations combined with MS for analysis of glycosaminoglycans

The glycosaminoglycan (GAG) family of polysaccharides includes the unsulfated hyaluronan and the sulfated heparin, heparan sulfate, keratan sulfate, and chondroitin/dermatan sulfate. GAGs are biosynthesized by a series of enzymes, the activities of which are controlled by complex factors. Animal cells alter their responses to different growth conditions by changing the structures of GAGs expressed on their cell surfaces and in extracellular matrices. Because this variation is a means whereby the functions of the limited number of protein gene products in animal genomes is elaborated, the phenotypic and functional assessment of GAG structures expressed spatially and temporally is an important goal in glycomics. On-line mass spectrometric separations are essential for successful determination of expression patterns for the GAG compound classes due to their inherent complexity and heterogeneity. Options include size exclusion, anion exchange, reversed phase, reversed phase ion pairing, hydrophilic interaction, and graphitized carbon chromatographic modes and capillary electrophoresis. This review summarizes the application of these approaches to on-line MS analysis of the GAG classes.

Isoenzyme-specific differences in the degradation of hyaluronic acid by mammalian-type hyaluronidases

Bovine testicular hyaluronidase (BTH) has been used as a spreading factor for many years and was primarily characterized by its enzymatic activity. As recombinant human hyaluronidases are now available the bovine preparations can be replaced by the human enzymes. However, data on the pH-dependent activity of hyaluronidases reported in literature are inconsistent in part or even contradictory. Detection of the pH-dependent activity of PH-20 type hyaluronidases, i.e. recombinant human PH-20 (rhPH-20) and BTH, showed a shift of the pH optimum from acidic pH values in a colorimetric activity assay to higher pH values in a turbidimetric activity assay. Contrarily, recombinant human Hyal-1 (rhHyal-1) and bee venom hyaluronidase (BVH) exhibited nearly identical pH profiles in both commonly used types of activity assays. Analysis of the hyaluronic acid (HA) degradation products by capillary zone electrophoresis showed that hyaluronan was catabolized by rhHyal-1 continuously into HA oligosaccharides. BTH and, to a less extent, rhPH-20 exhibited a different mode of action: at acidic pH (pH 4.5) HA was degraded as described for rhHyal-1, while at elevated pH (pH 5.5) small oligosaccharides were produced in addition to HA fragments of medium molecular weight, thus explaining the pH-dependent discrepancies in the activity assays. Our results suggest a sub-classification of mammalian-type hyaluronidases into a PH-20/BTH and a Hyal-1/BVH subtype. As the biological effects of HA fragments are reported to depend on the size of the molecules it can be speculated that different pH values at the site of hyaluronan degradation may result in different biological responses.

Diversity in the degree of sulfation and chain length of the glycosaminoglycan moiety of urinary trypsin inhibitor isomers

Five isomers with different electric charge were fractionated from human urinary trypsin inhibitor (UTI) by anion exchange HPLC. Intact low-sulfated chondroitin 4-sulfate chains from the isomers were analyzed by HPLC and mass spectrometry. Unsaturated disaccharide composition analysis of the chondroitin sulfate chain revealed that the five isomers differ in the numbers of 4-sulfated disaccharide units. Intriguingly, we detected the presence of multiple novel isomers with different numbers of non-sulfated disaccharide units even in the same charge isomer fraction. Our results demonstrate that UTI can vary in terms of both the degree of sulfation and the length of the low-sulfated chondroitin 4-sulfate chain.

Tandem mass spectrometric strategies for determination of sulfation positions and uronic acid epimerization in chondroitin sulfate oligosaccharides

Chondroitin sulfate (CS) is a glycosaminoglycan consisting of repeating (HexA-GalNAc sulfate) disaccharides, the functions of which depend on patterns of sulfation and uronic acid epimerization. The correlation of biological activities with structure requires a strategy to determine the sequences of CS oligosaccharides without the need for total isolation. Tandem mass spectrometry has enabled the development of proteomics, based on CID fragmentation of ions produced from complex mixtures of proteolytic peptides, and has the potential for rapid sequencing of CS and other glycosaminoglycan classes. The most challenging aspects of CS sequencing are to distinguish GalNAc residues sulfated at the 4- versus the 6-position and uronic acid epimers. This work describes the utility of (1) reducing terminal derivatives and (2) control of precursor ion charge state for tandem mass spectrometric strategies for determining GalNAc sulfation positional isomers of CS. The capability of tandem MS to differentiate uronic acid epimers is also shown, providing evidence that complete or nearly complete information on CS covalent structure may be obtained using tandem MS.

Tandem mass spectrometry of sulfated heparin-like glycosaminoglycan oligosaccharides

The structural characterization of heparin-like glycosaminoglycans (HLGAGs) is a major challenge in glycobiology. These linear, sulfated oligosaccharides are expressed on animal cell surfaces, in extracellular matrixes, basement membranes, and mast cell granules and bind with varying degrees of specificity to families of proteases, growth factors, chemokines, and blood coagulation proteins. Cell surface HLGAGs bind growth factors and growth factor receptors and serve as coreceptors in these interactions. Understanding of the mechanism and regulation of growth factor-receptor binding requires efficient determination of cell surface HLGAG structures and the variations in their expression in response to the cellular environment. The solution to this problem entails rapid, sensitive structural analysis of these molecules. To date, HLGAG sequencing requires multistep processes that combine chemical and enzymatic degradation with gel-based or mass spectrometry-based detection systems. Although tandem mass spectrometry has revolutionized proteomics, the fragility of sulfate groups has limited its usefulness in the analysis of HLGAGs. This work demonstrates that tandem mass spectrometry can be effectively used to determine HLGAG structures while minimizing losses of SO3. First, collision-induced dissociation (CID) is shown to produce abundant backbone cleavage ions for HLGAG oligosaccharides, provided that most sulfate groups are deprotonated. Fragmentation of different precursor ion charge states produces complementary data on the structure of the HLGAG. Second, calcium ion complexation of HLGAGs stabilizes the sulfate groups, increases the relative abundances of backbone cleavage ions, and decreases the abundances of ions produced from SO3 losses.

Comparative characterization of bovine testicular hyaluronidase and a hyaluronate lyase from Streptococcus agalactiae in pharmaceutical preparations

Although bovine testicular hyaluronidase (BTH) has been used in several medical fields for many years, these drugs are poorly characterized. We compared pharmaceutical BTH preparations (Neopermease, Hylase "Dessau") and a hyaluronate lyase from Streptococcus agalactiae. The BTH preparations were complex mixtures of proteins (SDS-PAGE, gel filtration) with enzymatic activity in different fractions. In the case of Neopermease the highest specific activity was found in the 58 kDa fraction (optimum at pH 3.6), whereas the 77 and 33 kDa fractions showed markedly lower specific activities at an optimal pH of 6.2. Maximum specific activity of the bacterial enzyme (approx. 1000 micromol min(-1) mg(-1)) was found at pH 5.0, being 410- and 5100-times higher compared to Neopermease and Hylase "Dessau", respectively. The hyaluronate lyase preparation was separated into two main proteins [100 kDa (pI=8.9) and 85 kDa (pI=9.2)] which were enzymatically active in SDS substrate-PAGE. Zymography after limited proteolysis of the bacterial enzyme with trypsin revealed active fragments (75-50 kDa). Our results suggest that hyaluronate lyase is an alternative for BTH, of which there has been a shortage, since companies have stopped the production of BTH preparations due to the risk of BSE.

Monte Carlo simulation of hyaluronidase reaction involving hydrolysis, transglycosylation and condensation

The action of hyaluronidase on oligosaccharides from hyaluronan is complicated due to branched reaction paths containing hydrolysis, transglycosylation and condensation. The unit component of hyaluronan is a disaccharide, namely GlcA-(beta 1-->3)-GlcNAc where GlcA and GlcNAc are d-glucuronic acid and d-N-acetylglucosamine respectively. Hyaluronan is the linear polymer formed by these disaccharide units, linked together with beta 1-->4 glycosidic bonds. Bovine testicular hyaluronidase acts only at beta 1-->4 glycosidic bonds of hyaluronan. The progress of product distribution from short oligosaccharides was simulated with the Monte Carlo method using the probabilistic model. The model consists only of a single enzyme molecule and a finite number of substrate and water molecules. The simulation is based on a simple reaction scheme and proceeds via an algorithm with minimum adjustable parameters generating random numbers and probabilities. The experimental data for bovine testicular hyaluronidase using [GlcA-(beta 1-->3)-GlcNAc](4) as the starting substrate were quantitatively simulated with only three adjustable parameters. The simulated data for [GlcA-(beta 1-->3)-GlcNAc](3) and [GlcA-(beta 1-->3)-GlcNAc](5) as the starting substrates agreed semi-quantitatively with experimental data using the same parameters. The mechanism of the hyaluronidase reaction is a combination of branched probabilistic cycles. The condensation reaction is much weaker than the transglycosylation reaction but contributes to product distribution at the final stage of the reaction, preventing complete hydrolysis of the substrates.

Syntheses of the 4-nitrophenyl glycosides of hyalobiuronic acid and chondrosine

4-Nitrophenyl [sodium beta-D-glucopyranosyluronate]-(1-->3)-2-acetamido-2-deoxy-beta-D-glucopyranoside (1) and 4-nitrophenyl [sodium beta-D-glucopyranosyluronate]-(1-->3)-2-acetamido-2-deoxy-beta-D-galactopyranoside (2) were prepared from the zwitterions hyalobiuronic acid [beta-D-glucopyranuronic acid-(1-->3)-2-amino-2-deoxy-D-glucopyranose] and chondrosine [beta-D-glucopyranuronic acid-(1-->3)-2-amino-2-deoxy-D-galactopyranose], respectively. Compounds 1 and 2 were not hydrolysed by bovine testicular hyaluronidase.

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.

Domain structure of chondroitin sulfate E octasaccharides binding to type V collagen

We demonstrated previously that chondroitin sulfate E (ChS-E) binds to type V collagen (Munakata, H., Takagaki, K., Majima, M., and Endo, M. (1999) Glycobiology 9, 1023--1027). In this study, we investigated the structure and binding of ChS-E oligosaccharides. Eleven oligosaccharides were isolated from ChS-E by gel filtration chromatography and anion-exchange high performance liquid chromatography after hydrolysis with testicular hyaluronidase. Separately, seven oligosaccharides were custom synthesized using the transglycosylation reaction of testicular hyaluronidase. Structural analysis was performed by enzymatic digestions in conjunction with high performance liquid chromatography and mass spectrometry. This library of 18 oligosaccharides was used as a source of model molecules to clarify the structural requirements for binding to type V collagen. Binding was analyzed by a biosensor based on surface plasmon resonance. The results indicated that to bind to type V collagen the oligosaccharides must have the following carbohydrate structures: 1) octasaccharide or larger in size; 2) a continuous sequence of three GlcAbeta1--3GalNAc(4S,6S) units; 3) a GlcAbeta1--3GalNAc(4S,6S) unit, GlcAbeta1--3GalNAc(4S) unit or GlcAbeta1--3GalNAc(6S) unit at the reducing terminal; 4) a GlcAbeta1--3GalNAc(4S,6S) unit at the nonreducing terminal. It is likely that these characteristic oligosaccharide sequences play key roles in cell adhesion and extracellular matrix assembly.

Anomalous migration of hyaluronic acid oligomers in capillary electrophoresis: correlation to susceptibility to hyaluronidase

During high-resolution capillary electrophoresis analysis in an electrolyte solution containing a neutral polymer, small oligomers of regularly arranged acidic polysaccharides such as hyaluronic acid and N-acetylneuraminic acid polymers showed reversal of the migration order. This anomalous migration was well correlated with their reported biological activity. In the present study, we analyzed hyaluronidase action on the purified hyaluronic acid oligomers using capillary electrophoresis and found that hydrolytic and transglycosylation actions by hyaluronidase were dependent on the molecular sizes of hyaluronic acid oligomers, and well correlated to their migration profiles. Furthermore, fluorescent polarization technique was employed for understanding the relationship between molecular size of hyaluronic acid oligomers and their electromigrations.

Characterization of Hyaluronidase Isolated from Agkistrodon contortrix contortrix (Southern Copperhead) Venom

Snake venoms are a rich source of enzymes including many hydrolytic enzymes. Some enzymes such as phospholipase A2, proteolytic enzymes, and phosphodiesterases are well characterized. However many enzymes, such as the glycosidase, hyaluronidase, have not been studied extensively. Here we describe the characterization of snake venom hyaluronidase. In order to determine which venom was the best source for isolation of the enzyme, the hyaluronidase activity of 19 venoms from Elapidae, Viperidae, and Crotalidae snakes was determined. Since Agkistrodon contortrix contortrix venom showed the highest activity, this venom was used for purification of hyaluronidase. Molecular weight was determined by matrix-assisted laser desorption ionization mass spectroscopy and was found to be 59,290 Da. The molecular weight value as determined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis was 61,000 Da. Substrate specificity studies indicated that the snake venom enzyme was specific only for hyaluronan and did not hydrolyze similar polysaccharides of chondroitin, chondroitin sulfate A (chondroitin 4-sulfate), chondroitin sulfate B (dermatan sulfate), chondroitin sulfate C (chondroitin 6-sulfate), chondroitin sulfate D, chondroitin sulfate E, or heparin. The enzyme is an endo-glycosidase without exo-glycosidase activity, as it did not hydrolyze p-nitrophenyl-beta-D-glucuronide or p-nitrophenyl-N-acetyl-beta-D-glucosaminide. The main hydrolysis products from hyaluronan were hexa- and tetrasaccharides with N-acetylglucosamine at the reducing terminal. The cleavage point is at the beta1,4-glycosidic linkage and not at the beta1,3-glycosidic linkage. Thus, snake venom hyaluronidase is an endo-beta-N-acetylhexosaminidase specific for hyaluronan.

Crystal structure of hyaluronidase, a major allergen of bee venom

BACKGROUND

Hyaluronic acid (HA) is the most abundant glycosaminoglycan of vertebrate extracellular spaces and is specifically degraded by a beta-1,4 glycosidase. Bee venom hyaluronidase (Hya) shares 30% sequence identity with human hyaluronidases, which are involved in fertilization and the turnover of HA. On the basis of sequence similarity, mammalian enzymes and Hya are assigned to glycosidase family 56 for which no structure has been reported yet.

RESULTS

The crystal structure of recombinant (Baculovirus) Hya was determined at 1.6 A resolution. The overall topology resembles a classical (beta/alpha)(8) TIM barrel except that the barrel is composed of only seven strands. A long substrate binding groove extends across the C-terminal end of the barrel. Cocrystallization with a substrate analog revealed the presence of a HA tetramer bound to subsites -4 to -1 and distortion of the -1 sugar.

CONCLUSIONS

The structure of the complex strongly suggest an acid-base catalytic mechanism, in which Glu113 acts as the proton donor and the N-acetyl group of the substrate is the nucleophile. The location of the catalytic residues shows striking similarity to bacterial chitinase which also operates via a substrate-assisted mechanism.

Hyaluronidase can be used to reduce interstitial edema in the presence of heparin

BACKGROUND

Treatment with the hyaluronan-degrading enzyme, hyaluronidase, reduces rejection-induced interstitial edema of transplanted organs. Hyaluronidase has also been demonstrated to reduce tissue necrosis after experimentally induced myocardial infarction, but its clinical use has been limited by an observed interaction between heparin and hyaluronan. In the present work, we investigated whether it is also possible to retain the effect of the enzyme in heparinized animals.

METHODS

Day 5 after heterotopic heart transplantation, recipient rats received a 2-hour intravenous infusion of hyaluronidase, either of ovine or of bovine origin. Concomitantly, the animals received intravenous heparin, either as 2 bolus doses or as a constant infusion.

RESULTS

Both hyaluronidase preparations effective reduced the hyaluronan content as well as the water content of the rejecting cardiac grafts. The concomitant use of heparin did not hamper the positive results, neither when heparin was administered intermittently nor when it was given continuously.

CONCLUSIONS

Our results in the transplantation model clearly demonstrate that hyaluronidase can be successfully used in heparinized individuals, provided that sufficient doses of the enzyme are given.

Enzymatic reconstruction of dermatan sulfate

We investigated the enzymatic reconstruction of dermatan sulfate (DS) using the transglycosylation reaction of testicular hyaluronidase. First, in order to insert the IdoA-GalNAc disaccharide unit into chondroitin sulfate chains consisting of GlcA-GalNAc disaccharide units, desulfated DS as a donor and pyridylaminated (PA) chondroitin 6-sulfate (Ch6S) hexasaccharide as an acceptor were subjected to a transglycosylation reaction using testicular hyaluronidase. The products were analyzed by HPLC, mass spectrometry, and enzymatic digestions, and the results indicated that one of the products was IdoA-GalNAc-(GlcA-GalNAc6S)(3)-PA. Next, when the resulting PA-Ch6S (hexa-)desulfated DS (di-)octasaccharide was used as an acceptor and chondroitin as a new donor, a decasaccharide having a GlcA-GalNAc-IdoA-GalNAc-(GlcA-GalNAc6S)(3) sequence was reconstructed. Using suitable combinations of donors and acceptors, it was possible to custom synthesize DS having any IdoA sequence as its uronic acid component. It is likely that application of this system would facilitate artificial reconstruction of variant DS having different specific functions.

Enzymatic reconstruction of a hybrid glycosaminoglycan containing 6-sulfated, 4-sulfated, and unsulfated N-acetylgalactosamine

Using the transglycosylation reaction of testicular hyaluronidase, reconstructions of hybrid glycosaminoglycans (GAGs) containing 6-sulfated (GalNAc6S), 4-sulfated (GalNAcS) and unsulfated N-acetylgalactosamine (GalNAc) were investigated. First, chondroitin 4-sulfate (Ch4S) as a donor containing GalNAc4S and the pyridylaminated (PA) chondroitin 6-sulfate (Ch6S) hexasaccharide as an acceptor containing GalNAc6S were subjected to transglycosylation reaction. Second, when the resulting PA-Ch6S(hexa-)-Ch4S(di-)octasaccharide and chondroitin (Ch) were used as an acceptor and as a donor containing GalNAc, respectively, a new decasaccharide having a hybrid structure composed of disaccharide units derived from Ch6S, Ch4S and Ch was reconstructed. Using a systematic combination of each donor and acceptor molecule, it was possible to reconstruct various types of hybrid GAGs.

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.

Specificity of the hyaluronate lyase of group-B streptococcus toward unsulphated regions of chondroitin sulphate

The purification and properties of a hyaluronate lyase secreted by Streptococcus agalactiae, which is believed to facilitate the invasion of host tissues by the organism, have been described previously [Pritchard, Lin, Willingham and Baker (1994) Arch. Biochem. Biophys. 315, 431-436]. The specificity of the limited cleavage of chondroitin sulphate by the enzyme is the subject of this report. To simplify the task, a chondroitin sulphate from the Swarm rat chondrosarcoma, which contains only 4-sulphated and unsulphated disaccharide repeats, was used in this study. Tetrasaccharides from an ovine testicular hyaluronidase digest of the chondroitin sulphate were isolated, identified and tested as substrates of the streptococcal hyaluronate lyase. Only tetrasaccharides with an unsulphated disaccharide at the reducing end were cleaved (by elimination at the N-acetylgalactosaminidic bond). Thus chondroitin sulphate chains are cleaved by the action of this lyase at every unsulphated disaccharide repeat, but release of unsaturated unsulphated disaccharides only occurs from sites where two or more sequential unsulphated disaccharide repeats are present. Analysis of the chondrosarcoma chondroitin sulphate showed that of approximately five unsulphated disaccharide repeats per chain, two are clustered. The ability of group-B streptococcal hyaluronate lyase to cleave chondroitin sulphate may allow the organisms to invade tissues more efficiently. The demonstrated specific and highly limited cleavage of chondroitin sulphate by this bacterial lyase promises to be a useful tool in the determination of chondroitin sulphate structure and variability.

In vitro mutagenesis of PH-20 hyaluronidase from human sperm

The cDNA encoding PH-20 hyaluronidase from human sperm has been mutated at five positions by in vitro mutagenesis. We have changed three acidic amino acids and two arginine residues that are conserved in the sequence of mammalian PH-20 polypeptides as well as in the hyaluronidases from bee and hornet venom. Of the former, the mutants [Gln113]PH-20 and [Gln249]PH-20 had no detectable enzymatic activity; the mutant [Asn111]PH-20 had about 3% activity. The mutant [Thr252]PH-20 was also inactive, while [Gly176]PH-20 had only about 1% activity. This indicates that the PH-20 hyaluronidases, like numerous enzymes that hydrolyze glycosidic bonds, have acidic amino acids in their active site. Moreover, for the binding of the substrate, the polyanion hyaluronan, arginine residues appear to be essential.

Neoglycoconjugates and their applications in glycobiology

Within the past two years new developments in neoglycoconjugate formation have increased the accessibility and usefulness of these probes for the analyses of glycan structure and function. This article reviews several simple chemical and enzymatic methods for tagging oligosaccharides with chromophores, biotin, peptides, proteins and lipids, and describes some representative applications of these neoglycoconjugates.

Hyaluronidases--a group of neglected enzymes

Hyaluronan is an important constituent of the extracellular matrix. This polysaccharide can be hydrolyzed by various hyaluronidases that are widely distributed in nature. The structure of some bacterial and animal enzymes of this type has recently been elucidated. It could be shown that the hyaluronidases from bee and hornet venom and the PH-20 hyaluronidase present on mammalian spermatozoa are homologous proteins.

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.