In Situ "Humanization" of Porcine Bioprostheses: Demonstration of Tendon Bioprostheses Conversion into Human ACL and Possible Implications for Heart Valve Bioprostheses

This review describes the first studies on successful conversion of porcine soft-tissue bioprostheses into viable permanently functional tissue in humans. This process includes gradual degradation of the porcine tissue, with concomitant neo-vascularization and reconstruction of the implanted bioprosthesis with human cells and extracellular matrix. Such a reconstruction process is referred to in this review as “humanization”. Humanization was achieved with porcine bone-patellar-tendon-bone (BTB), replacing torn anterior-cruciate-ligament (ACL) in patients. In addition to its possible use in orthopedic surgery, it is suggested that this humanization method should be studied as a possible mechanism for converting implanted porcine bioprosthetic heart-valves (BHV) into viable tissue valves in young patients. Presently, these patients are only implanted with mechanical heart-valves, which require constant anticoagulation therapy. The processing of porcine bioprostheses, which enables humanization, includes elimination of α-gal epitopes and partial (incomplete) crosslinking with glutaraldehyde. Studies on implantation of porcine BTB bioprostheses indicated that enzymatic elimination of α-gal epitopes prevents subsequent accelerated destruction of implanted tissues by the natural anti-Gal antibody, whereas the partial crosslinking by glutaraldehyde molecules results in their function as “speed bumps” that slow the infiltration of macrophages. Anti-non gal antibodies produced against porcine antigens in implanted bioprostheses recruit macrophages, which infiltrate at a pace that enables slow degradation of the porcine tissue, neo-vascularization, and infiltration of fibroblasts. These fibroblasts align with the porcine collagen-fibers scaffold, secrete their collagen-fibers and other extracellular-matrix (ECM) components, and gradually replace porcine tissues degraded by macrophages with autologous functional viable tissue. Porcine BTB implanted in patients completes humanization into autologous ACL within ~2 years. The similarities in cells and ECM comprising heart-valves and tendons, raises the possibility that porcine BHV undergoing a similar processing, may also undergo humanization, resulting in formation of an autologous, viable, permanently functional, non-calcifying heart-valves.

α-Galactosidase and Sucrose-Kinase Relationships in a Bi-functional AgaSK Enzyme Produced by the Human Gut Symbiont Ruminococcus gnavus E1

Plant α-galactosides belonging to the raffinose family oligosaccharides (RFOs) and considered as prebiotics, are commonly degraded by α-galactosidases produced by the human gut microbiome. In this environment, the Ruminococcus gnavus E1 symbiont-well-known for various benefit-is able to produce an original RgAgaSK bifunctional enzyme. This enzyme contains an hydrolytic α-galactosidase domain linked to an ATP dependent extra-domain, specifically involved in the α-galactoside hydrolysis and the phosphorylation of the glucose, respectively. However, the multi-modular relationships between both catalytic domains remained hitherto unexplored and has been, consequently, herein investigated. Biochemical characterization of heterologously expressed enzymes either in full-form or in separated domains revealed similar kinetic parameters. These results were supported by molecular modeling studies performed on the whole enzyme in complex with different RFOs. Further enzymatic analysis associated with kinetic degradation of various substrates followed by high pressure anionic exchange chromatography revealed that catalytic efficiency decreased as the number of D-galactosyl moieties branched onto the oligosaccharide increased, suggesting a preference of RgAgaSK for RFO's short chains. A wide prevalence and abundance study on a human metagenomic library showed a high prevalence of the RgAgaSK encoding gene whatever the health status of the individuals. Finally, phylogeny and synteny studies suggested a limited spread by horizontal transfer of the clusters' containing RgAgaSK to only few species of Firmicutes, highlighting the importance of these undispersed tandem activities in the human gut microbiome.

Crystal Structure of α-Galactosidase from Thermus thermophilus: Insight into Hexamer Assembly and Substrate Specificity

α-Galactosidase catalyzes the hydrolysis of a terminal α-galactose residue in galacto-oligosaccharides and has potential in various industrial applications and food processing. We determined the crystal structures of α-galactosidase from the thermophilic microorganism Thermus thermophilus (TtGalA) and its complexes with pNPGal and stachyose. The monomer folds into an N-terminal domain, a catalytic (β/α)₈ barrel domain, and a C-terminal domain. The domain organization is similar to that of the other family of 36 α-galactosidases, but TtGalA presents a cagelike hexamer. Structural analysis shows that oligomerization may be a key factor for the thermal adaption of TtGalA. The structure of TtGalA complexed with stachyose reveals only the existence of one -1 subsite and one +1 subsite in the active site. Structural comparison of the stachyose-bound complexes of TtGalA and GsAgaA, a tetrameric enzyme with four subsites, suggests evolutionary divergence of substrate specificity within the GH36 family of α-galactosidases. To the best of our knowledge, the crystal structure of TtGalA is the first report of a quaternary structure as a hexameric assembly in the α-galactosidase family.

Good hydrolysis activity on raffinose family oligosaccharides by a novel α-galactosidase from Tremella aurantialba

An α-galactosidase designated as TAG was purified from the dried fruit bodies of Tremella aurantialba with 182.5-fold purification. The purification procedure involved ion exchange chromatography on Q-sepharose, DEAE-Cellulose, and Mono Q and gel filtration by FPLC on Superdex 75. The purified α-galactosidase was a monomeric protein with a molecular mass of 88 kDa. The optimal pH of TAG was 5.0 and more than 60% of the original enzyme activity remained at pH 2.0 and 3.0. Its optimal temperature was 54 °C with good thermo-stability, 30.8% of the original activity was retained after exposure to a temperature of 70 °C for 1 h. The metal ions Hg²⁺, Cu²⁺, Fe³⁺ and Mg²⁺ strongly inhibited the enzyme activity. The enzyme activity was found to be inhibited by N-bromosuccinimide indicating that tryptophan was essential to the catalytic activity of α-galactosidase. The enzyme completely hydrolysed stachyose and partially hydrolysed raffinose to galactose at 50 °C within 6 h as detected by thin layer chromatography and the dinitrosalicylic acid method and the content of reducing sugar reached 4.36 mg/mL.

Diagnostic strategy for females suspected of Fabry disease

A total of 11 948 females suspicious of Fabry disease were tested by a combined biochemical and genetic approach. The enzyme activity, together with the concentration of lyso-GL-3 (lyso-Gb3) biomarker in dried blood spots (DBS), substantially improved the diagnostic detection of Fabry disease in females compared to the enzyme activity alone. Abnormal values for both were highly suspicious of Fabry disease (97% positive predictive value [PPV], similar to PPV in males). In cases with one abnormal biochemical value, elevated lyso-GL-3 is a far more important indicator than low enzyme activity (39% PPV vs 6% PPV). Cases with clearly negative results for both biochemical parameters are unlikely to have Fabry disease, even in clinically highly suspicious cases.

Renal involvement in paediatric Fabry disease

Anderson-Fabry Disease (AFD) is a rare, X-linked inborn error of glycosphingolipid catabolism caused by a deficient or absent activity of the lysosomal enzyme, α-galactosidase A, resulting in the progressive multisystem lysosomal accumulation of glycosphingolipids, mainly globotriaosylceramide (Gb3). Among the wide spectrum of clinical signs and symptoms and the life-threatening complications of Fabry disease, renal failure causes significant morbidity and mortality. Various evidence shows that the accumulation of Gb3 in different renal cells is present since the first years of life, many years and usually decades before manifest symptoms and signs of renal involvement. Early renal damage can be demonstrated by clinical signs as microalbuminuria and proteinuria, developing as early as in the second decade of life. A decline in GFR is uncommon at paediatric ages but may be seen as early as adolescence. Renal biopsy is rarely used in paediatric patients with Fabry disease although evidence shows that it may be considered a valid tool for the diagnosis of early and potentially reversible nephropathy, as well as for the evaluation of the effectiveness of enzyme replacement therapy (ERT). Although there is consensus in considering the early initiation of ERT as the only tool able to prevent the progression of nephropathy, the issue on the correct timing for the onset of ERT in pediatric age remains open in the management of this chronic and progressive disease.

Cross-linked α-galactosidase aggregates: optimization, characterization and application in the hydrolysis of raffinose-type oligosaccharides in soymilk

BACKGROUND

Cross-linked enzyme aggregates (CLEAs) of α-galactosidase, partially purified from maize (Zea mays) flour, were prepared. The impact of various parameters on enzyme activity was examined to optimize the immobilization procedure. Biochemical characterization of the free and immobilized enzyme was carried out. Stability (thermal, pH, storage and operational stability) and reusability tests were performed. The potential use of the free enzyme and the CLEAs in hydrolysis processes of raffinose-type oligosaccharides present in soymilk was investigated.

RESULTS

α-galactosidase CLEAs were prepared with 47% activity recovery under optimum conditions [1:5 (v/v) enzyme solution:saturated ammonium sulfate solution ratio; 7.5 mg protein and 0.1% (v/v) glutaraldehyde, 6 h, 4 °C, 150 rpm]. α-galactosidase CLEAs exhibited increased stability in comparison to the free enzyme. The CLEAs and the free enzyme showed a maximum activity at 40°C and their optimal pH values were5.5 and 6.0, respectively. Kinetic constants (K_M , V_max and k_cat ) were calculated for the free enzyme and the CLEAs in the presence of p-nitrophenyl-α-d-galactopyranoside, stachyose, melibiose and raffinose. The effect of various chemicals and sugars on enzyme activity showed that both enzyme forms were significantly inhibited by HgCl₂ and galactose. The CLEAs hydrolyzed 85% of raffinose and 96% of stachyose.

CONCLUSION

The α-galactosidase CLEAs, with their satisfactory enzymatic characteristics, have much potential for use in the food and feed industry. © 2019 Society of Chemical Industry.

Whole Conversion of Soybean Molasses into Isomaltulose and Ethanol by Combining Enzymatic Hydrolysis and Successive Selective Fermentations

Isomaltulose is mainly produced from sucrose by microbial fermentation, when the utilization of sucrose contributes a high production cost. To achieve a low-cost isomaltulose production, soy molasses was introduced as an alternative substrate. Firstly, α-galactosidase gene from Rhizomucor miehei was expressed in Yarrowia lipolytica, which then showed a galactosidase activity of 121.6 U/mL. Under the effects of the recombinant α-galactosidase, most of the raffinose-family oligosaccharides in soy molasses were hydrolyzed into sucrose. Then the soy molasses hydrolysate with high sucrose content (22.04%, w/w) was supplemented into the medium, with an isomaltulose production of 209.4 g/L, and the yield of 0.95 g/g. Finally, by virtue of the bioremoval process using Pichia stipitis, sugar byproducts in broth were transformed into ethanol at the end of fermentation, thus resulting in high isomaltulose purity (97.8%). The bioprocess employed in this study provides a novel strategy for low-cost and efficient isomaltulose production from soybean molasses.

Enhanced elimination of non-digestible oligosaccharides from soy milk by immobilized α-galactosidase: A comparative analysis

This study compared two immobilization matrices like calcium-alginate and chitosan for immobilization of α-galactosidase and evaluated their potential for the removal of non-digestible raffinose family oligosaccharides from soy milk which cause abdominal discomfort. The pH optima of the free and immobilized enzymes were found to be similar at pH 4.0. The chitosan-immobilized α-galactosidase displayed higher optimal temperature (60°C) compared to alginate-immobilized enzyme (45°C) and free enzyme (50°C). The chitosan-immobilized and alginate-immobilized α-galactosidases displayed 93.7% and 97.6% hydrolysis of raffinose family oligosaccharides, respectively, while the free enzyme hydrolyzed only 30.3% oligosaccharides present in soy milk in 4 hr. Remarkably, both the immobilized enzymes showed complete removal of raffinose family oligosaccharides in 8 hr. Moreover, reusability studies indicate that even after five cycles of reuse, the chitosan and alginate-immobilized enzymes displayed 99% and 60% hydrolysis, respectively. PRACTICAL APPLICATIONS: In this study, we have used two inexpensive and non-toxic matrices for immobilizing α-galactosidase. We report that entrapment of α-galactosidase with chitosan significantly improved the optimal temperature of α-galactosidase, which is advantageous in food industry. The hydrolysis of raffinose family oligosaccharides in soy milk was also greatly enhanced after immobilization with chitosan and alginate. Thus, the results described in this study have relevance for development of safe, cost-effective and efficient method for removal of non-digestible soy oligosaccharides in food industry.

The melREDCA Operon Encodes a Utilization System for the Raffinose Family of Oligosaccharides in Bacillus subtilis

Bacillus subtilis is a heterotrophic soil bacterium that hydrolyzes different polysaccharides mainly found in the decomposed plants. These carbohydrates are mainly cellulose, hemicellulose, and the raffinose family of oligosaccharides (RFOs). RFOs are soluble α-galactosides, such as raffinose, stachyose, and verbascose, that rank second only after sucrose in abundance. Genome sequencing and transcriptome analysis of B. subtilis indicated the presence of a putative α-galactosidase-encoding gene (melA) located in the msmRE-amyDC-melA operon. Characterization of the MelA protein showed that it is a strictly Mn²⁺- and NAD⁺-dependent α-galactosidase able to hydrolyze melibiose, raffinose, and stachyose. Transcription of the msmER-amyDC-melA operon is under control of a σ^A-type promoter located upstream of msmR (P _msmR ), which is negatively regulated by MsmR. The activity of P _msmR was induced in the presence of melibiose and raffinose. MsmR is a transcriptional repressor that binds to two binding sites at P _msmR located upstream of the -35 box and downstream of the transcriptional start site. MsmEX-AmyCD forms an ATP-binding cassette (ABC) transporter that probably transports melibiose into the cell. Since msmRE-amyDC-melA is a melibiose utilization system, we renamed the operon melREDCA IMPORTANCE Bacillus subtilis utilizes different polysaccharides produced by plants. These carbohydrates are primarily degraded by extracellular hydrolases, and the resulting oligo-, di-, and monosaccharides are transported into the cytosol via phosphoenolpyruvate-dependent phosphotransferase systems (PTS), major facilitator superfamily, and ATP-binding cassette (ABC) transporters. In this study, a new carbohydrate utilization system of B. subtilis responsible for the utilization of α-galactosides of the raffinose family of oligosaccharides (RFOs) was investigated. RFOs are synthesized from sucrose in plants and are mainly found in the storage organs of plant leaves. Our results revealed the modus operandi of a new carbohydrate utilization system in B. subtilis.

Multiple phenotypic domains of Fabry disease and their relevance for establishing genotype- phenotype correlations

Fabry disease (FD) is a rare X-linked glycosphingolipidosis resulting from deficient α-galactosidase A (AGAL) activity, caused by pathogenic mutations in the GLA gene. In males, the multisystemic involvement and the severity of tissue injury are critically dependent on the level of AGAL residual enzyme activity (REA) and on the metabolic load of the disease, but organ susceptibility to damage varies widely, with heart appearing as the most vulnerable to storage pathology, even with relatively high REA. The expression of FD can be conceived as a multidomain phenotype, where each of the component domains is the laboratory or clinical expression of the causative GLA mutation along a complex pathophysiologic cascade pathway. The AGAL enzyme activity is the most clinically useful marker of the protein phenotype. The metabolic phenotype and the pathologic phenotype are diverse expressions of the storage pathology, respectively, assessed by biochemical and histological/ultrastructural methods. The storage phenotypes are the direct consequences of enzyme deficiency and hence, together with the enzymatic phenotype, constitute the more specific diagnostic markers of FD. In the pathophysiology cascade, the clinical phenotypes are most distantly linked to the underlying genetic causation, being critically influenced by the patients’ gender and age, and modulated by the effects of variation in other genetic loci, of polygenic inheritance and of environmental risk factors. A major challenge in the clinical phenotyping of patients with FD is the differential diagnosis between its nonspecific, later-onset complications, particularly the cerebrovascular, cardiac and renal, and similar chronic illnesses that are common in the general population. Comprehensive phenotyping, whenever possible performed in hemizygous males, is therefore crucial for grading the severity of pathogenic GLA variants, to clarify the phenotypic correlations of hypomorphic alleles, to define benign polymorphisms, as well as to establish the pathogenicity of variants of uncertain significance.

Three novel mutations in α-galactosidase gene involving in galactomannan degradation in endosperm of curd coconut

The deficiency of α-galactosidase activity in coconut endosperm has been reported to cause a disability to hydrolyze oligogalactomannan in endosperm resulting in curd coconut phenotype. However, neither the α-galactosidase encoding gene in coconut nor the mutation type has been identified and characterized in normal and curd coconuts. In this study, cDNA and genomic DNA encoding α-galactosidase gene alleles from a normal and two curd coconuts were successfully cloned and characterized. The deduced amino acid of wild type α-galactosidase contains 398 amino acid residues with a 17 N-terminal amino acids signal peptide sequence. Three mutant alleles, the first 19-amino acids from 67 to 85 (ADALVSTGLARLGYQYVNL) deletion with S137R and the second R216T, were identified from curd coconut plant no.1 while the third P250R was identified from curd coconut plant no. 10. All mutations of α-galactosidase gene were confirmed by the analysis of parental genomic DNA from normal and curd coconuts. Heterologous expression in Komagataella phaffii (Pichia pastoris) indicated that recombinant P250R, R216T and 19-amino acids deletion-S137R mutant proteins showed no α-galactosidase activity. Only the recombinant wild-type protein was able to detect for α-galactosidase activity. These results are in accordance with the no detection of α-galactosidase activity in developing curd coconut endosperms by tissue staining. While, the accumulation of enzyme activity was present in the solid endosperm of normal coconut. The full-length cDNA and parental genomic DNA sequences encoding α-galactosidase in normal coconut as well as identified curd coconut mutant alleles are reported in Genbank accession no. KJ957156 and KM001681-3. Transcription level of the α-galactosidase gene in mature curd coconut endosperm was at least 20 times higher than normal. In conclusion, absence of α-galactosidase activity caused by gene mutations associates with an accumulation of oligogalactomannan in endosperms, resulting in curd coconut phenotype.

Galactomannan Degrading Enzymes from the Mannan Utilization Gene Cluster of Alkaliphilic Bacillus sp. N16-5 and Their Synergy on Galactomannan Degradation

Two glycoside hydrolases encoded by the mannan utilization gene cluster of alkaliphilic Bacillus sp. N16-5 were studied. The recombinant Gal27A (rGal27A) hydrolyzed both galactomannans and oligo-galactomannans to release galactose, while the recombinant Man113A (rMan113A) showed poor activity toward galactomannans, but it hydrolyzed manno-oligosaccharides to release mannose and mannobiose. rGal27A showed synergistic interactions with rMan113A and recombinant β-mannanase ManA (rManA), which is also from Bacillus sp. N16-5, in galactomannan degradation. The synergy degree of rGal27A and rManA on hydrolysis of locust bean gum and guar gum was 1.13 and 2.21, respectively, and that of rGal27A and rMan113A reached 2.00 and 2.68. The main products of galactomannan hydrolyzed by rGal27A and rManA simultaneously were galactose, mannose, mannobiose, and mannotriose, while those of galactomannan hydrolyzed by rGal27A and rMan113A were galactose and mannose. The yields of mannose, mannobiose, and mannotriose dramatically increased compared with the hydrolysis in the presence of rManA or rMan113A alone.

Podocyturia in paediatric patients with Fabry disease

INTRODUCTION

Fabry disease (FD) is a hereditary disorder caused by a deficiency of α-galactosidase A enzyme activity. The transmission of the disorder is linked to the X chromosome.

OBJECTIVES

The objectives of the study were: 1. To quantify the presence of podocytes in paediatric patients with FD and compare them with the value of the measured podocyturia in healthy controls. 2. To determine whether a greater podocyturia is related to the onset of pathological albuminuria in patients with FD. 3. To determine the risk factors associated with pathological albuminuria.

METHODS

We performed an analytical, observational study of Fabry and control subjects, which were separated into 2groups in accordance with the absence of the disease (control group) or the presence of the disease (Fabry group).

RESULTS

We studied 31 patients, 11 with FD and 20 controls, with a mean age of 11.6 years. The difference between the mean time elapsed from the diagnosis of FD to the measurement of podocyturia (40 months) and the onset of pathological albuminuria (34 months) was not significant (p=0.09). Podocytes were identified by staining for the presence of synaptopodin and the mean quantitative differences between both podocyturias were statistically significant (p=0.001). Albuminuria was physiological in 4 of the patients with FD and the relative risk to develop pathological albuminuria according to podocyturia was 1.1 in the control group and 3.9 in the Fabry group, with a coefficient of correlation between podocyturia and albuminuria in the Fabry group of 0.8354. Finally, the 2 risk factors associated with the development of pathological albuminuria were podocyturia (OR: 14) and being aged over 10 years (OR: 18). We found no significant risk with regard to glomerular filtrate renal (GFR) (OR: 0.5) or gender (OR: 1.3). The mean GFR remained within normal values.

CONCLUSION

The detection of podocyturia in paediatric patients with FD could be used as an early marker of renal damage, preceding and proportional to the occurrence of pathological albuminuria.

Nicotiana benthamiana α-galactosidase A1.1 can functionally complement human α-galactosidase A deficiency associated with Fabry disease

α-Galactosidases (EC 3.2.1.22) are retaining glycosidases that cleave terminal α-linked galactose residues from glycoconjugate substrates. α-Galactosidases take part in the turnover of cell wall-associated galactomannans in plants and in the lysosomal degradation of glycosphingolipids in animals. Deficiency of human α-galactosidase A (α-Gal A) causes Fabry disease (FD), a heritable, X-linked lysosomal storage disorder, characterized by accumulation of globotriaosylceramide (Gb3) and globotriaosylsphingosine (lyso-Gb3). Current management of FD involves enzyme-replacement therapy (ERT). An activity-based probe (ABP) covalently labeling the catalytic nucleophile of α-Gal A has been previously designed to study α-galactosidases for use in FD therapy. Here, we report that this ABP labels proteins in Nicotiana benthamiana leaf extracts, enabling the identification and biochemical characterization of an N. benthamiana α-galactosidase we name here A1.1 (gene accession ID GJZM-1660). The transiently overexpressed and purified enzyme was a monomer lacking N-glycans and was active toward 4-methylumbelliferyl-α-d-galactopyranoside substrate (Km = 0.17 mm) over a broad pH range. A1.1 structural analysis by X-ray crystallography revealed marked similarities with human α-Gal A, even including A1.1's ability to hydrolyze Gb3 and lyso-Gb3, which are not endogenous in plants. Of note, A1.1 uptake into FD fibroblasts reduced the elevated lyso-Gb3 levels in these cells, consistent with A1.1 delivery to lysosomes as revealed by confocal microscopy. The ease of production and the features of A1.1, such as stability over a broad pH range, combined with its capacity to degrade glycosphingolipid substrates, warrant further examination of its value as a potential therapeutic agent for ERT-based FD management.

High-throughput sequencing and culture-based approaches to analyze microbial diversity associated with chemical changes in naturally fermented tofu whey, a traditional Chinese tofu-coagulant

Naturally fermented tofu whey (NFTW) has been used as traditional tofu coagulant in China for hundreds of years. In this study, the microbial diversity in NFTW was firstly analyzed with high-throughput sequencing and its effect on chemical contents of tofu whey (TW) was investigated. Lactobacillus with 95.31% was the predominant genus in the microbial community of NFTW while Picha, Enterococcus, Bacillus and Acetobacter occupied about only 0.90%, 0.04%, 0.02% and 0.09%, respectively. Besides, Lactobacillus amylolyticus were determined to be one of the dominated species with metagenomic analysis and culture method. Lactobacillus with α-galactosidase activities played leading role in metabolizing the soybean oligosaccharides of TW to produce lactic acid. And acetic acid produced by genus of Acetobacter was another main organic acid attributed to the acidification of TW except lactic acid. Meanwhile, the bioconversion of isoflavone glucosides into aglycones could also be promoted by Lactobacillus with the help of β-glucosidase activity. Moreover, the production of equol in NFTW was confirmed, which might be jointly converted from daidzein by several strains. Therefore, our results indicated that Lactobacillus was the dominated microorganism and mainly affected the chemical changes of NFTW. This study help provide basic theory and technical references for the production of tofu and its derivative products (like sufu) with NFTW as coagulator.

Synthesis of Stachyobifiose Using Bifidobacterial α-Galactosidase Purified from Recombinant Escherichia coli

The prebiotic effects of GOS (galactooligosaccharides) are known to depend on the glycosidic linkages, degree of polymerization (DP), and the monosaccharide composition. In this study, a novel form of α-GOS with a potentially improved prebiotic effect was synthesized using bifidobacterial α-galactosidase (α-Gal) purified from recombinant Escherichia coli. The carbohydrate produced was identified as α-d-galactopyranosyl-(1→6)-O-α-d-glucopyranosyl-(1→2)-[α-d-galactopyranosyl-(1→6)-O-β-d-fructofuranoside] and was termed stachyobifiose. Among 17 nonprobiotics, 16 nonprobiotics showed lower growth on stachyobifiose than β-GOS. In contrast, among the 16 probiotics, 6 probiotics showed higher growth on stachyobifiose than β-GOS. When compared with raffinose, stachyobifiose was used less by nonprobiotics than raffinose. Moreover, compared with stachyose, stachyobifiose was used less by Escherichia coli, Enterobacter cloacae, and Clostridium butyricum. The average amounts of total short-chain fatty acids (SCFA) produced were in the order of stachyobifiose > stachyose > raffinose > β-GOS. Taken together, stachyobifiose is expected to contribute to beneficial changes of gut microbiota.

Heterologous expression and characterization of an Arabidopsis β-l-arabinopyranosidase and α-d-galactosidases acting on β-l-arabinopyranosyl residues

The major plant sugar l-arabinose (l-Ara) has two different ring forms, l-arabinofuranose (l-Araf) and l-arabinopyranose (l-Arap). Although l-Ara mainly appears in the form of α-l-Araf residues in cell wall components, such as pectic α-1,3:1,5-arabinan, arabinoxylan, and arabinogalactan-proteins (AGPs), lesser amounts of it can also be found as β-l-Arap residues of AGPs. Even though AGPs are known to be rapidly metabolized, the enzymes acting on the β-l-Arap residues remain to be identified. In the present study, four enzymes, which we call β-l-ARAPASE (APSE) and α-GALACTOSIDASE 1 (AGAL1), AGAL2, and AGAL3, are identified as those enzymes that are likely to be responsible for the hydrolysis of the β-l-Arap residues in Arabidopsis thaliana. An Arabidopsis apse-1 mutant showed significant reduction in β-l-arabinopyranosidase activity, and an apse-1 agal3-1 double-mutant exhibited even less activity. The apse-1 and the double-mutants both had more β-l-Arap residues in the cell walls than wild-type plants. Recombinant APSE expressed in the yeast Pichia pastoris specifically hydrolyzed β-l-Arap residues and released l-Ara from gum arabic and larch arabinogalactan. The recombinant AGAL3 also showed weak β-l-arabinopyranosidase activity beside its strong α-galactosidase activity. It appears that the β-l-Arap residues of AGPs are hydrolysed mainly by APSE and partially by AGALs in Arabidopsis.

Human Alpha Galactosidases Transiently Produced in Nicotiana benthamiana Leaves: New Insights in Substrate Specificities with Relevance for Fabry Disease

Deficiency of α-galactosidase A (α-GAL) causes Fabry disease (FD), an X-linked storage disease of the glycosphingolipid globtriaosylcerammide (Gb3) in lysosomes of various cells and elevated plasma globotriaosylsphingosine (Lyso-Gb3) toxic for podocytes and nociceptive neurons. Enzyme replacement therapy is used to treat the disease, but clinical efficacy is limited in many male FD patients due to development of neutralizing antibodies (Ab). Therapeutic use of modified lysosomal α-N-acetyl-galactosaminidase (α-NAGAL) with increased α-galactosidase activity (α-NAGAL^EL) has therefore been suggested. We transiently produced in Nicotiana benthamiana leaves functional α-GAL, α-NAGAL, and α-NAGAL^EL enzymes for research purposes. All enzymes could be visualized with activity-based probes covalently binding in their catalytic pocket. Characterization of purified proteins indicated that α-NAGAL^EL is improved in activity toward artificial 4MU-α-galactopyranoside. Recombinant α-NAGAL^EL and α-NAGAL are not neutralized by Ab-positive FD serum tested and are more stable in human plasma than α-GAL. Both enzymes hydrolyze the lipid substrates Gb3 and Lyso-Gb3 accumulating in Fabry patients. The addition to FD sera of α-NAGAL^EL, and to a lesser extent that of α-NAGAL, results in a reduction of the toxic Lyso-Gb3. In conclusion, our study suggests that modified α-NAGAL^EL might reduce excessive Lyso-Gb3 in FD serum. This neo-enzyme can be produced in Nicotiana benthamiana and might be further developed for the treatment of FD aiming at reduction of circulating Lyso-Gb3.

Chemical and structural characterization of α-N-acetylgalactosaminidase I and II from starfish, asterina amurensis

BACKGROUND

The marine invertebrate starfish was found to contain a novel α-N-acetylgalactosaminidase, α-GalNAcase II, which catalyzes removal of terminal α-N-acetylgalactosamine (α-GalNAc), in addition to a typical α-N-acetylgalactosaminidase, α-GalNAcase I, which catalyzes removal of terminal α-N-acetylgalactosamine (α-GalNAc) and, to a lesser extent, galactose. The interrelationship between α-GalNAcase I and α-GalNAcase II and the molecular basis of their differences in substrate specificity remain unknown.

RESULTS

Chemical and structural comparisons between α-GalNAcase I and II using immunostaining, N-terminal amino acid sequencing and peptide analysis showed high homology to each other and also to other glycoside hydrolase family (GHF) 27 members. The amino acid sequence of peptides showed conserved residues at the active site as seen in typical α-GalNAcase. Some substitutions of conserved amino acid residues were found in α-GalNAcase II that were located near catalytic site. Among them G171 and A173, in place of C171 and W173, respectively in α-GalNAcase were identified to be responsible for lacking intrinsic α-galactosidase activity of α-GalNAcase II. Chemical modifications supported the presence of serine, aspartate and tryptophan as active site residues. Two tryptophan residues (W16 and W173) were involved in α-galactosidase activity, and one (W16) of them was involved in α-GalNAcase activity.

CONCLUSIONS

The results suggested that α-GalNAcase I and II are closely related with respect to primary and higher order structure and that their structural differences are responsible for difference in substrate specificities.

Induced Remodeling of Porcine Tendons to Human Anterior Cruciate Ligaments by α-GAL Epitope Removal and Partial Cross-Linking

This review describes a novel method developed for processing porcine tendon and other ligament implants that enables in situ remodeling into autologous ligaments in humans. The method differs from methods using extracellular matrices (ECMs) that provide postoperative orthobiological support (i.e., augmentation grafts) for healing of injured ligaments, in that the porcine bone-patellar-tendon-bone itself serves as the graft replacing ruptured anterior cruciate ligament (ACL). The method allows for gradual remodeling of porcine tendon into autologous human ACL while maintaining the biomechanical integrity. The method was first evaluated in a preclinical model of monkeys and subsequently in patients. The method overcomes detrimental effects of the natural anti-Gal antibody and harnesses anti-non-gal antibodies for the remodeling process in two steps: Step 1. Elimination of α-gal epitopes—this epitope that is abundant in pigs (as in other nonprimate mammals) binds the natural anti-Gal antibody, which is the most abundant natural antibody in humans. This interaction, which can induce fast resorption of the porcine implant, is avoided by enzymatic elimination of α-gal epitopes from the implant with recombinant α-galactosidase. Step 2. Partial cross-linking of porcine tendon with glutaraldehyde—this cross-linking generates covalent bonds in the ECM, which slow infiltration of macrophages into the implant. Anti-non-gal antibodies are produced in recipients against the multiple porcine antigenic proteins and proteoglycans because of sequence differences between human and porcine homologous proteins. Anti-non-gal antibodies bind to the implant ECM, recruit macrophages, and induce the implant destruction by directing proteolytic activity of macrophages. Partial cross-linking of the tendon ECM decreases the extent of macrophage infiltration and degradation of the implant and enables concomitant infiltration of fibroblasts that follow the infiltrating macrophages. These fibroblasts align with the implant collagen fibers and secrete their own collagen and other ECM proteins, which gradually remodel the porcine tendon into human ACL. This ligamentization process lasts ∼2 years and the biomechanical integrity of the graft is maintained throughout the whole period. These studies are the first, and so far the only, to demonstrate remodeling of porcine tendon implants into permanently functional autologous ACL in humans.

The Large Phenotypic Spectrum of Fabry Disease Requires Graduated Diagnosis and Personalized Therapy: A Meta-Analysis Can Help to Differentiate Missense Mutations

Fabry disease is caused by mutations in the GLA gene and is characterized by a large genotypic and phenotypic spectrum. Missense mutations pose a special problem for graduating diagnosis and choosing a cost-effective therapy. Some mutants retain enzymatic activity, but are less stable than the wild type protein. These mutants can be stabilized by small molecules which are defined as pharmacological chaperones. The first chaperone to reach clinical trial is 1-deoxygalactonojirimycin, but others have been tested in vitro. Residual activity of GLA mutants has been measured in the presence or absence of pharmacological chaperones by several authors. Data obtained from transfected cells correlate with those obtained in cells derived from patients, regardless of whether 1-deoxygalactonojirimycin was present or not. The extent to which missense mutations respond to 1-deoxygalactonojirimycin is variable and a reference table of the results obtained by independent groups that is provided with this paper can facilitate the choice of eligible patients. A review of other pharmacological chaperones is provided as well. Frequent mutations can have residual activity as low as one-fourth of normal enzyme in vitro. The reference table with residual activity of the mutants facilitates the identification of non-pathological variants.

Enzymatic synthesis of novel oligosaccharides from N-acetylsucrosamine and melibiose using Aspergillus niger α-galactosidase, and properties of the products

Two kinds of oligosaccharides, N-acetylraffinosamine (RafNAc) and N-acetylplanteosamine (PlaNAc), were synthesized from N-acetylsucrosamine and melibiose using the transgalactosylation activity of Aspergillus niger α-galactosidase. RafNAc and PlaNAc are novel trisaccharides in which d-glucopyranose residues in raffinose (Raf) and planteose are replaced with N-acetyl-d-glucosamine. These trisaccharides were more stable in acidic solution than Raf. RafNAc was hydrolyzed more rapidly than Raf by α-galactosidase of green coffee bean. In contrast, RafNAc was not hydrolyzed by Saccharomyces cerevisiae invertase, although Raf was hydrolyzed well by this enzyme. These results indicate that the physicochemical properties and steric structure of RafNAc differ considerably from those of Raf.

Characterization of a Glycoside Hydrolase Family 27 α-Galactosidase from Pontibacter Reveals Its Novel Salt-Protease Tolerance and Transglycosylation Activity

α-Galactosidases are of great interest in various applications. A glycoside hydrolase family 27 α-galactosidase was cloned from Pontibacter sp. harbored in a saline soil and expressed in Escherichia coli. The purified recombinant enzyme (rAgaAHJ8) was little or not affected by 3.5-30.0% (w/v) NaCl, 10.0-100.0 mM Pb(CH3COO)2, 10.0-60.0 mM ZnSO4, or 8.3-100.0 mg mL(-1) trypsin and by most metal ions and chemical reagents at 1.0 and 10.0 mM concentrations. The degree of synergy on enzymatic degradation of locust bean gum and guar gum by an endomannanase and rAgaAHJ8 was 1.22-1.54. In the presence of trypsin, the amount of reducing sugars released from soybean milk treated by rAgaAHJ8 was approximately 3.8-fold compared with that treated by a commercial α-galactosidase. rAgaAHJ8 showed transglycosylation activity when using sucrose, raffinose, and 3-methyl-1-butanol as the acceptors. Furthermore, potential factors for salt adaptation of the enzyme were presumed.

Does oral α-galactosidase relieve irritable bowel symptoms?

OBJECTIVE

Abdominal bloating is reported by a majority of irritable bowel syndrome (IBS) patients. Excess colonic fermentation may cause gaseous symptoms. Several foodstuffs contain oligosaccharides with an α-galactosidic linkage that is resistant to mammalian hydrolases. Assisted hydrolysis by exogenous α-galactosidase enzyme (AG) could offer a way of controlling IBS symptoms by reducing colonic fermentation and gas production. The aim of this study was to assess the effect of AG on symptom severity and quality of life in IBS patients with abdominal bloating or flatulence.

METHODS

A total of 125 subjects with IBS received AG or placebo at meals for 12 weeks. IBS-Symptom Severity Score (IBS-SSS) and quality of life (QoL) were assessed at baseline, during the treatment and at 4-week follow-up.

RESULTS

AG showed a trend toward a more prominent decrease in IBS-SSS. The responder rate at week 16 was higher for the AG group. No difference was detected in QoL between AG and placebo groups. A total of 25 patients (18 in AG group and 7 in placebo group, p = 0.016) withdrew from the study. Abdominal pain and diarrhea were more often reported as reason for withdrawal in AG group.

CONCLUSIONS

We found no evidence to support the use of AG routinely in IBS patients. Improvement of clinical response at 4-week follow-up may suggest a long-term effect of unknown mechanism, but could also be attributed to non-responder drop out. Gastrointestinal (GI) side effects may be a coincidence in this study, but irritation of GI tract by AG administration cannot be excluded.