Kinetics of Hyal-1 and PH-20 hyaluronidases: comparison of minimal substrates and analysis of the transglycosylation reaction

The availability of recombinant expression systems for the production of purified human hyaluronidases PH-20 and Hyal-1 facilitated the first detailed analysis of the enzymatic reaction products. The human recombinant enzymes, both expressed by Drosophila Schneider-2 (DS-2) cells, were compared to bovine testicular hyaluronidase (BTH), a commercially available hyaluronidase preparation, which has long been considered a prototype of mammalian hyaluronidases. The conversion of low molecular weight hyaluronic acid (HA) fragments was detected by a capillary zone electrophoresis (CZE) method. Surprisingly, the HA hexasaccharide, which is generally accepted to be the minimum substrate of BTH, was not a substrate of recombinant human PH-20 and Hyal-1. However, HA octasaccharide was converted efficiently by both enzymes, thus representing the minimum substrate for human PH-20 and Hyal-1. Additionally, BTH was shown to catabolize the HA hexasaccharide at pH 4.0 mainly by hydrolysis, while at pH 6.0 transglycosylation prevailed. Human PH-20 was found to catalyze both hydrolysis and transglycosylation of the HA octasaccharide. On the contrary, human Hyal-1 converted the HA octasaccharide mainly by hydrolysis with transglycosylation products occurring only at high substrate concentrations (> or = 500 microM). The differences between the hyaluronidase subtypes and isoenzymes were much more prominent than expected. Obviously, the different hyaluronidase subtypes have evolved into very specialized enzymes with respect to their catalytic mechanism of action.     

CD44-dependent intracellular and extracellular catabolism of hyaluronic acid by hyaluronidase-1 and -2

Hyaluronic acid (HA) is a high molecular weight glycosaminoglycan involved in a wide variety of cellular functions. However, its turnover in living cells remains largely unknown. In this study, CD44, a receptor for HA, and hyaluronidase-1, -2, and -3 (Hyal-1, -2 and -3) were stably expressed in HEK 293 cells and the mechanism of HA catabolism was systematically investigated using fluorescein-labeled HA. CD44 was essential for HA degradation by both endogenous and exogenously expressed hyaluronidases. Hyal-1 was not able to cleave HA in living cells in the absence of CD44. Intracellular HA degradation was predominantly mediated by Hyal-1 after incorporation of HA by CD44. Although Hyal-1 was active only in intracellular space in vivo, a certain amount of the enzyme was secreted to extracellular space. This extracellular Hyal-1 was found to be incorporated by cells and such uptake of Hyal-1 was, in part, involved in the intracellular degradation of HA. Hyal-2 was involved in the extracellular degradation of HA. Hyal-2 activity was also dependent on the expression of CD44 in both living cells and enzyme assays. Immunofluorescent microscopy demonstrated that both Hyal-2 and CD44 are present on the cell surface. Without CD44 expression, Hyal-2 existed in a granular pattern, and did not show hyaluronidase activity, suggesting that localization change could contribute to Hyal-2 function. A convenient and quantitative enzyme assay was established for the measurement of Hyal-2 activity. Hyal-2 activity was detected in the membrane fraction of cells co-expressing Hyal-2 and CD44. The pH optimum for Hyal-2 was 6.0-7.0. The membrane fraction of cells expressing Hyal-2 alone did not show hyaluronidase activity. Hyal-3 did not show any hyaluronidase activity in our experimental conditions. Based on these findings, Hyal-1 and -2 contribute to intracellular and extracellular catabolism of HA, respectively, in a CD44-dependent manner, and their HA degradation occurs independently from one another.     

Hyaluronidase expression in human skin fibroblasts

Hyaluronidase activity has been detected for the first time in normal human dermal fibroblasts (HS27), as well as in fetal fibroblasts (FF24) and fibrosarcoma cells (HT1080). Enzymatic activity was secreted predominantly into the culture media, with minor amounts of activity associated with the cell layer. In both classes of fibroblasts, hyaluronidase expression was confluence-dependent, with highest levels of activity occurring in quiescent, post-confluent cells. However, in the fibrosarcoma cell cultures, expression was independent of cell density. The enzyme had a pH optimum of 3.7 and on hyaluronan substrate gel zymography, activity occurred as a single band corresponding to an approximate molecular size of 57 kDa. The enzyme could be immunoprecipitated in its entirety using monoclonal antibodies raised against Hyal-1, human plasma hyaluronidase. PCR confirmed that fibroblast hyaluronidase was identical to Hyal-1. The conclusion by previous investigators using earlier technologies that fibroblasts do not contain hyaluronidase activity should be reevaluated.     

Mouse liver lysosomes contain enzymatically active processed forms of Hyal-1

It has long been known that liver lysosomes contain an endoglycosidase activity able to degrade the high molecular mass glycosaminoglycan hyaluronic acid (HA). The identification and cloning of a hyaluronidase with an acidic pH optimum, Hyal-1, suggested it might be responsible for this activity. However, we previously reported that this hydrolase could only be detected in pre-lysosomal compartments of the mouse liver using a zymography technique that allows the detection of Hyal-1 activity after SDS–PAGE (“renatured protein zymography”). Present work reveals that the activity highlighted by this technique belongs to a precursor form of Hyal-1 and that the lysosomal HA endoglycosidase activity of the mouse liver is accounted for by a proteolytically processed form of Hyal-1 that can only be detected using “native protein zymography”. Indeed, the distribution of this form follows the distribution of β-galactosidase, a well-established lysosomal marker, after fractionation of the mouse liver in a linear sucrose density gradient. In addition, both activities shift toward the lower density region of the gradient when a specific decrease of the lysosomal density is induced by Triton WR-1339 injection. The fact that only native protein zymography but not renatured protein zymography is able to detect Hyal-1 activity in lysosomes points to a non-covalent association of Hyal-1 proteolytic fragments or the existence of closely linked partners supporting Hyal-1 enzymatic activity. The knockdown of Hyal-1 results in an 80% decrease of total acid hyaluronidase activity in the mouse liver, confirming that Hyal-1 is a key actor of HA catabolism in this organ.     

The six hyaluronidase-like genes in the human and mouse genomes.

The human genome contains six hyaluronidase-like genes. Three genes (HYAL1, HYAL2 and HYAL3) are clustered on chromosome 3p21.3, and another two genes (HYAL4 and PH-20/SPAM1) and one expressed pseudogene (HYALP1) are similarly clustered on chromosome 7q31.3. The extensive homology between the different hyaluronidase genes suggests ancient gene duplication, followed by en masse block duplication, events that occurred before the emergence of modern mammals. Very recently we have found that the mouse genome also has six hyaluronidase-like genes that are also grouped into two clusters of three, in regions syntenic with the human genome. Surprisingly, the mouse ortholog of HYALP1 does not contain any mutations, and unlike its human counterpart may actually encode an active enzyme. Hyal-1 is the only hyaluronidase in mammalian plasma and urine, and is also found at high levels in major organs such as liver, kidney, spleen, and heart. A model is proposed suggesting that Hyal-2 and Hyal-1 are the major mammalian hyaluronidases in somatic tissues, and that they act in concert to degrade high molecular weight hyaluronan to the tetrasaccharide. Twenty-kDa hyaluronan fragments are generated at the cell surface in unique endocytic vesicles resulting from digestion by the glycosylphosphatidyl-inositol-anchored Hyal-2, transported intracellularly by an unknown process, and then further digested by Hyal-1. The two beta-exoglycosidases, beta-glucuronidase and beta-N-acetyl glucosaminidase, remove sugars from reducing termini of hyaluronan oligomers, and supplement the hyaluronidases in the catabolism of hyaluronan.     

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.     

Enhanced activity of serum and urinary hyaluronidases in streptozotocin-induced diabetic Wistar and GK rats

Using streptozotocin-induced diabetic Wistar and GK rats as models of type 1 and type 2 diabetes, respectively, we investigated the changes in serum and urinary hyaluronidase activity with the pathological progress. The serum hyaluronidase levels of streptozotocin-induced rats started to increase on the third day after injection and thereafter maintained approximately threefold higher levels compared with control rats; those of GK rats were already higher ( approximately twofold) from the beginning of the experiment. The increases of serum hyaluronidase activity in both diabetic rats were similar to those of blood glucose level, indicating that diabetes mellitus was accompanied by enhanced activity of circulating hyaluronidase from the early phase of its development. In zymography, every serum from diabetic and control rats gave two hyaluronidase isomers, a major 73-kDa band (Hyal-1 type) and a minor 132-kDa band, suggesting that the increases in serum hyaluronidase activity were not due to the appearance of novel isomers. The hyaluronidase activity in 24-h urine of streptozotocin-induced rats was 3-, 7-, and 11-fold higher at the 8th, 15th, and 18th week than that of control rats, respectively, and the urinary hyaluronidase activity of GK rats was not significantly different from controls. There was a good correlation between the urinary hyaluronidase activity and the albumin excretion. Thus the increase in urinary hyaluronidase activity may reflect enhanced glomerular permeability in streptozotocin-induced diabetic rats and may be a useful marker for diabetic nephropathy. Relative resistance to SDS-denaturation in zymography of rat serum and urinary hyaluronidases compared with human serum hyaluronidase are also shown.     

Xenopus kidney hyaluronidase-1 (XKH1), a novel type of membrane-bound hyaluronidase solely degrades hyaluronan at neutral pH

In search for Xenopus laevis hyaluronidase genes, a cDNA encoding a putative PH-20-like enzyme was isolated. In the adult frog, this mRNA was only found to be expressed in the kidney and therefore named XKH1. When expressed by means of cRNA injection into frog oocytes, XKH1 solely exhibited at physiologic ionic strength hyaluronidase activity at neutral pH and in weakly acidic solutions. The enzyme was inactive below pH 5.4. In addition to hyaluronic acid hydrolysis, chondroitin sulfate also was degraded at low yield as assessed by fluorophore-assisted carbohydrate electrophoresis analysis of the degradation products. The enzyme is sorted to the outer surface of the cell membrane of XKH1 expressing oocytes. From there, it could not be removed by phospholipase C nor was secreted hyaluronidase activity detectable. We conclude that XKH1 represents a membrane-bound hyaluronan-degrading enzyme exclusively expressed in cells of the adult frog kidney where it either may be involved in the reorganization of the extracellular architecture or in supporting physiological demands for proper renal functions.     

CD44 interaction with Na+-H+ exchanger (NHE1) creates acidic microenvironments leading to hyaluronidase-2 and cathepsin B activation and breast tumor cell invasion

We have explored CD44 (a hyaluronan (HA) receptor) interaction with a Na(+)-H(+) exchanger (NHE1) and hyaluronidase-2 (Hyal-2) during HA-induced cellular signaling in human breast tumor cells (MDA-MB-231 cell line). Immunological analyses demonstrate that CD44s (standard form) and two signaling molecules (NHE1 and Hyal-2) are closely associated in a complex in MDA-MB-231 cells. These three proteins are also significantly enriched in cholesterol and ganglioside-containing lipid rafts, characterized as caveolin and flotillin-rich plasma membrane microdomains. The binding of HA to CD44 activates Na(+)-H(+) exchange activity which, in turn, promotes intracellular acidification and creates an acidic extracellular matrix environment. This leads to Hyal-2-mediated HA catabolism, HA modification, and cysteine proteinase (cathepsin B) activation resulting in breast tumor cell invasion. In addition, we have observed the following: (i) HA/CD44-activated Rho kinase (ROK) mediates NHE1 phosphorylation and activity, and (ii) inhibition of ROK or NHE1 activity (by treating cells with a ROK inhibitor, Y27632, or NHE1 blocker, S-(N-ethyl-N-isopropyl) amiloride, respectively) blocks NHE1 phosphorylation/Na(+)-H(+) exchange activity, reduces intracellular acidification, eliminates the acidic environment in the extracellular matrix, and suppresses breast tumor-specific behaviors (e.g. Hyal-2-mediated HA modification, cathepsin B activation, and tumor cell invasion). Finally, down-regulation of CD44 or Hyal-2 expression (by treating cells with CD44 or Hyal-2-specific small interfering RNAs) not only inhibits HA-mediated CD44 signaling (e.g. ROK-mediated Na(+)-H(+) exchanger reaction and cellular pH changes) but also impairs oncogenic events (e.g. Hyal-2 activity, hyaluronan modification, cathepsin B activation, and tumor cell invasion). Taken together, our results suggest that CD44 interaction with a ROK-activated NHE1 (a Na(+)-H(+) exchanger) in cholesterol/ganglioside-containing lipid rafts plays a pivotal role in promoting intracellular/extracellular acidification required for Hyal-2 and cysteine proteinase-mediated matrix degradation and breast cancer progression.     

Serum hyaluronidase aberrations in metabolic and morphogenetic disorders

Hyaluronidases are endo-glycosidases that degrade both hyaluronan (hyaluronic acid) (HA) and chondroitin sulfates. Deficiency of hyaluronidase activity has been predicted to result in a phenotype similar to that observed in mucopolysaccharidosis (MPS). In the present study, we surveyed a variety of patients with phenotypes similar to those observed in MPS, but without significant mucopolysacchariduria to determine if some are based on aberrations in serum hyaluronidase (Hyal-1) activity. The study included patients with well-characterized dysmorphic disorders occurring on genetic basis, as well as those of unkown etiology. The purpose of the study was to establish how wide spread were abnormalities in levels of circulating Hyal-1 activity. A simple and sensitive semi-quantitative zymographic procedure was used for the determination of activity. Levels of both beta-N-acetylglucosaminidase and beta-glucuronidase whose activities contribute to the total breakdown of hyaluronan (HA) were also measured, as well as the concentration of circulating HA. Among 48 patients with bone or connective tissue abnormalities, low levels of Hyal-1 activity were found in six patients compared to levels in 100 healthy donors (2.0-3.2 units/microL vs 6(+/- 1 SE) units/microL). These six patients exhibited a wide spectrum of clinical abnormalities, in particular shortened extremities: they included three patients with unknown causes of clinical symptoms, one patient with Sanfilippo disease, one of the seven patients with achondroplasia, and one with hypophosphotemic rickets. Normal levels of serum Hyal-1 activities were found in patients with Morquio disease, GM1 gangliosidosis, I cell-disease, 6 of the 7 patients with achondroplasia, Marfan's-syndrome and Ehlers-Danlos syndrome. No patient totally lacked serum Hyal-1 activity. Serum HA concentration was elevated in patients with Sanfilippo A and I-cell disease. Determination of serum and leukocyte Hyal-1 and serum HA may be useful to evaluate patients with metabolic and morphogenetic disorders.     

Expression of Torpedo californica creatine kinase in Escherichia coli and purification from inclusion bodies

The pET17 expression vector was used to express creatine kinase from the electric organ of Torpedo californica as inclusion bodies in Escherichia coli BL21(DE3) cells. The insoluble aggregate was dissolved in 8M urea and, following extraction with Triton X-100, the enzyme was refolded by dialysis against Tris buffer (pH 8.0) containing 0.2M NaCl. After two buffer changes, chromatography on Blue Sepharose was used as a final step in the purification procedure. Approximately 54mg active protein was recovered from a 1L culture and the refolded enzyme had a specific activity of 75U/mg. The molecular mass of the purified protein was consistent with that predicted from the amino acid sequence and the CD spectrum of the refolded enzyme was essentially identical to that of creatine kinase from human muscle (HMCK). The K(m) values of ATP and ADP were also similar to those of HMCK, while the K(m) values for both phosphocreatine and creatine were approximately 5-10-fold higher. The purification described here is in marked contrast with earlier attempts at purification of this isozyme where, in a process yielding less than 1mg/L culture, enzyme with a specific activity of ca. 5U/mg was obtained.     

Hyaluronidase in sera of tumour-bearing nude mice

Cancer cell lines often secrete hyaluronidase, suggesting that this enzyme could be used as a marker of growing tumours. We have measured hyaluronidase in the sera of non-grafted mice and mice grafted with human tumour-derived hyaluronidase-secreting H460M and SA87 cells or non-secreting CB 193 cells. Mouse serum hyaluronidase was measured at pH 3.8 using the enzyme-linked sorbent assay (ELSA) technique by reference to human serum whose activity at pH 3.8 was determined by the Reissig technique. The serum hyaluronidase in non-grafted mice ranged from 310-520 mU l^-1 (mean±SD 432±70 mU l^-1, median 440 mU l^-1). Hyaluronidase increased in the sera of tumour-bearing mice grafted with H460M cells or with SA87 cells, but not in the sera of mice grafted with CB 193 cells. Serum hyaluronidase activity in H460M or SA87 tumour-bearing mice correlated with the tumour mass, increased with time, and decreased after tumour removal. Zymography detected two different hyaluronidase forms in the sera of non-grafted mice: type 1 had only one hyaluronidase band and type 2 had five different bands. In both types, enzyme augmentation in tumour-bearing mice correlated with the presence of an additional enzyme band that was not seen in normal sera and that migrated as the cancer cell enzyme did; there was no augmentation of the normal isoform(s). These results show that serum hyaluronidase can be used to follow the development of tumours in mice grafted with hyaluronidase-secreting cells.     

Hyaluronidase in sera of tumour-bearing nude mice

Cancer cell lines often secrete hyaluronidase, suggesting that this enzyme could be used as a marker of growing tumours. We have measured hyaluronidase in the sera of non-grafted mice and mice grafted with human tumour-derived hyaluronidase-secreting H460M and SA87 cells or non-secreting CB 193 cells. Mouse serum hyaluronidase was measured at pH 3.8 using the enzyme-linked sorbent assay (ELSA) technique by reference to human serum whose activity at pH 3.8 was determined by the Reissig technique. The serum hyaluronidase in non-grafted mice ranged from 310-520 mU l^?1 (mean±SD 432±70 mU l^?1, median 440 mU l^?1). Hyaluronidase increased in the sera of tumour-bearing mice grafted with H460M cells or with SA87 cells, but not in the sera of mice grafted with CB 193 cells. Serum hyaluronidase activity in H460M or SA87 tumour-bearing mice correlated with the tumour mass, increased with time, and decreased after tumour removal. Zymography detected two different hyaluronidase forms in the sera of non-grafted mice: type 1 had only one hyaluronidase band and type 2 had five different bands. In both types, enzyme augmentation in tumour-bearing mice correlated with the presence of an additional enzyme band that was not seen in normal sera and that migrated as the cancer cell enzyme did; there was no augmentation of the normal isoform(s). These results show that serum hyaluronidase can be used to follow the development of tumours in mice grafted with hyaluronidase-secreting cells.     

Hyaluronidase in sera of tumour-bearing nude mice.

Cancer cell lines often secrete hyaluronidase, suggesting that this enzyme could be used as a marker of growing tumours. We have measured hyaluronidase in the sera of non-grafted mice and mice grafted with human tumour-derived hyaluronidase-secreting H460M and SA87 cells or non-secreting CB 193 cells. Mouse serum hyaluronidase was measured at pH 3.8 using the enzyme-linked sorbent assay (ELSA) technique by reference to human serum whose activity at pH 3.8 was determined by the Reissig technique. The serum hyaluronidase in non-grafted mice ranged from 310-520 mU l(-1) (mean+/-SD 432+/-70 mU l(-1), median 440 mU l(-1)). Hyaluronidase increased in the sera of tumour-bearing mice grafted with H460M cells or with SA87 cells, but not in the sera of mice grafted with CB 193 cells. Serum hyaluronidase activity in H460M or SA87 tumour-bearing mice correlated with the tumour mass, increased with time, and decreased after tumour removal. Zymography detected two different hyaluronidase forms in the sera of non-grafted mice: type 1 had only one hyaluronidase band and type 2 had five different bands. In both types, enzyme augmentation in tumour-bearing mice correlated with the presence of an additional enzyme band that was not seen in normal sera and that migrated as the cancer cell enzyme did; there was no augmentation of the normal isoform(s). These results show that serum hyaluronidase can be used to follow the development of tumours in mice grafted with hyaluronidase-secreting cells.     

Production d'hyaluronidase par les cellules cancéreuses humaines en culture

The presence of hyaluronidase was detected at pH 3.8 in eight out of twelve human cancer cell line culture media. Eight cell lines derived from primary tumours and four from metastases. In three culture media the enzymatic activity was lower than 0.035 pU/cell/h. In five others (in a hepatoma cell line and in four metastasis-derived cell lines) the activity was higher than 0.057 pU/cell/h. A tumour-derived fibroblast culture was negative. The optimal activity was observed at a pH comprised between 3.6 and 4. Salt inhibition of hyaluronidase was reversible. The enzyme was denaturated by a 10-min heating at 70 °C. The enzyme was not strictly specific for hyaluronan hydrolysis but also digested chondroitin sulfates. PH20, a spermatozoid protein that has homologies with the bee venom hyaluronidase, was not expressed by cell lines tested.     

Synthesis of 1-(2,6,6-Trimethyl-4-hydroxy-1-cyclohexen-1-yl)-1,3-butanedione

Streptococcus dysgalactiae IID 678, belonging to group C of the streptococci, secreted a large amount of hyaluronidase (hyaluronate lyase, EC 4.2.2.1) into a culture medium containing hyaluronic acid. The purification procedures of hyaluronidase were 70% ammonium sulfate precipitation, ECTEOLA-cellulose chromatography, phospho-cellulose chromatography, and gel filtration on Sephacryl S-300. The hyaluronidase was purified approximately 27,000-fold from the culture filtrate. The purified enzyme was homogeneous by SDS-poIyacrylamide gel electrophoresis. The enzyme degradated only hyaluronic acid and chondroitin to zl 4,5-unsaturated disaccharides and did not act on other glycosaminoglycans containing sulfate groups, while the degradation rate of chondroitin was about 1/60 of that of hyaluronic acid. The optimum pH was wide, from pH 5.8 to pH 6.6, and the optimum temperature was 37°C. Fe^{2 +}, Cu^{2 +}, Pb^{2 +}, and Hg^{2 +} ions inhibited the activity strongly and Zn²⁺ inhibited it by half. The molecular weight of the enzyme was estimated to be 125,000 by gel filtration and 117,000 by SDS-polyacrylamide gel electrophoresis. The enzyme was different immunochemically from the hyaluronidase from Streptococcus pyogenes belonging to group A.     

Transforming growth factor-β1 blocks the enhancement of tumor necrosis factor cytotoxicity by hyaluronidase Hyal-2 in L929 fibroblasts

Background  

Functional antagonism between transforming growth factor beta (TGF-β) and hyaluronidase has been demonstrated. For example, testicular hyaluronidase PH-20 counteracts TGF-β1-mediated growth inhibition of epithelial cells. PH-20 sensitizes various cancer cells to tumor necrosis factor (TNF) cytotoxicity by upregulating proapoptotic p53 and WW domain-containing oxidoreductase (WOX1). TGF-β1 blocks PH-20-increased TNF cytotoxicity. In the present study, the functional antagonism between TGF-β1 and lysosomal hyaluronidases Hyal-1 and Hyal-2 was examined.     

东亚钳蝎毒透明质酸酶的纯化和部分性质的研究

用CM-SephadexC50,CM-SephadexC25和SephadexG-75凝胶过滤,从东亚钳蝎毒中提纯蝎毒透明质酸酶,应用低pH系统不连续聚丙烯酰胺凝胶圆盘电泳,SDS-不连续聚丙烯酰胺凝胶垂直板电泳鉴定均为单一条带,活力提高34倍,产率为12％,纯品无出血活性,无神经毒性。用凝胶过滤法和SDS电泳法测得分子量为54000,PAS染色证实为糖蛋白。 纯化的透明质酸酶的最适pH为4.5～6.5,最适温度为37℃,该酶对热的稳定性比蛇毒透明质酸酶高一些,但在碱性环境中也易失活。0.15MNaCl对酶活性有明显稳定作用,Fe~(2+)、Fe~(3+)及肝素对酶活性有明显的抑制作用,Cu~(2+)对酶活力也有一定影响。     

A recommended procedure for the estimation of bovine testicular hyaluronidase in the presence of human serum

A procedure is described for the assay of bovine testicular hyaluronidase in human blood following intravenous administration of the enzyme. Inhibition of hyaluronidase by the reported nonspecific serum inhibitor is minimal. However, the presence of human serum does alter the pH profile of hyaluronidase and enhances the activity of the enzyme at low pH values. Preliminary data indicates that the effects caused by serum on the pH optimum and activity of the enzyme are largely associated with the albumin fraction and are not due to the presence of endogenous serum hyaluronidase. The activation effect is not specific for any particular blood type and is independent of whether serum or citrated plasma is used. A similar effect to that of serum on hyaluronidase activity is produced by different buffer mixtures or increased NaCl concentration. It is recommended that bovine testicular hyaluronidase be measured at pH 4.0 in 0.1 m sodium citrate buffer containing 0.15 m NaCl as under these conditions the addition of human serum or citrated plasma does not alter the pH optimum of the enzyme. These recommendations necessitate certain modifications of the reducing N-acetylhexosamine assay method of Reissig et al. (J. L. Reissig, J. L. Strominger, and L. F. Leloir, 1955, J. Biol. Chem.217, 959–966).     

An affinity adsorbent, 5'-adenylate-aminohexyl-sepharose. I. Purification and properties of two forms of RNase U2

An affinity adsorbent, 5'-adenylate-aminohexyl-Sepharose 4B, was prepared by the periodate oxidation of AMp followed by coupling and condensation with amino-hexyl-Sepharose 4B. RNase U2, a purine-specific RNase, was specifically bound to this adsorbent at pH 4.5 and eluted critically at pH 5.9 in the presence of 1 M NaCl, corresponding to the pH dependence of the binding of 2'-AMP to RNase U2. By using this affinity chromatography as a main tool, a simplified and effective purification method for RNase U2 was established with a high yield of 58%. Another form of RNase U2 with low specific activity, named RNase U2-B, was eluted at a slightly higher pH from this adsorbent. RNase U2-B was indistinguishable from the original enzyme (RNase U2-A) in base specificity, affinity for ApA, molecular weight and amino acid composition, but was clearly different in specific activity, molecular activity for ApA, isoelectric point and conformation of molecule. This affinity adsorbent is also effective for the detection or isolation of small amounts of base-specific RNases in crude cell extract.