Development of a 1,2-difluorofucoside activity-based probe for profiling GH29 fucosidases.

GH29 α-l-fucosidases catalyze hydrolysis of terminal α-l-fucosyl linkages with varying specificity and are expressed by prominent members of the human gut microbiota. Both homeostasis and dysbiosis at the human intestinal microbiota interface have been correlated with altered fucosidase activity. Herein we describe the development of a 2-deoxy-2-fluoro fucosyl fluoride derivative with an azide mini-tag as an activity-based probe (ABP) for selective in vitro labelling of GH29 α-l-fucosidases. Only catalytically active fucosidases are inactivated by this ABP, allowing their functionalization with a biotin reporter group via the CuAAC reaction and subsequent in-gel detection at nanogram levels. The ABP we present here is shown to be active against a GH29 α-l-fucosidase from Bacteroides fragilis and capable of labeling two other GH29 α-l-fucosidases with different linkage specificity, illustrating its broader utility. This novel ABP is a valuable addition to the toolbox of fucosidase probes by allowing identification and functional studies of the wide variety of GH29 fucosidases, including those in the gut microbiota.

A Novel Online Calculator Based on Serum Biomarkers to Detect Hepatocellular Carcinoma among Patients with Hepatitis B.

BACKGROUND: Early detection of hepatocellular carcinoma (HCC) among hepatitis B virus (HBV)-infected patients remains a challenge, especially in China. We sought to create an online calculator of serum biomarkers to detect HCC among patients with chronic hepatitis B (CHB). METHODS: Participants with HBV-HCC, CHB, HBV-related liver cirrhosis (HBV-LC), benign hepatic tumors, and healthy controls (HCs) were recruited at 11 Chinese hospitals. Potential serum HCC biomarkers, protein induced by vitamin K absence or antagonist-II (PIVKA-II), α-fetoprotein (AFP), lens culinaris agglutinin A-reactive fraction of AFP (AFP-L3) and α-l-fucosidase (AFU) were evaluated in the pilot cohort. The calculator was built in the training cohort via logistic regression model and validated in the validation cohort. RESULTS: In the pilot study, PIVKA-II and AFP showed better diagnostic sensitivity and specificity compared with AFP-L3 and AFU and were chosen for further study. A combination of PIVKA-II and AFP demonstrated better diagnostic accuracy in differentiating patients with HBV-HCC from patients with CHB or HBV-LC than AFP or PIVKA-II alone [area under the curve (AUC), 0.922 (95% CI, 0.908-0.935), sensitivity 88.3% and specificity 85.1% for the training cohort; 0.902 (95% CI, 0.875-0.929), 87.8%, and 81.0%, respectively, for the validation cohort]. The nomogram including AFP, PIVKA-II, age, and sex performed well in predicting HBV-HCC with good calibration and discrimination [AUC, 0.941 (95% CI, 0.929-0.952)] and was validated in the validation cohort [AUC, 0.931 (95% CI, 0.909-0.953)]. CONCLUSIONS: Our results demonstrated that a web-based calculator including age, sex, AFP, and PIVKA-II accurately predicted the presence of HCC in patients with CHB. CLINICALTRIALSGOV IDENTIFIER: NCT03047603.

Alpha-L-fucosidase-1 is a diagnostic marker that distinguishes mucoepidermoid carcinoma from squamous cell carcinoma.

Alpha-L-fucose is a component of glycans on the cell surface. Alpha-L-fucose is correlated with tumorigenesis and malignancy, and alpha-L-fucosidase-1 (FUCA1), the enzyme that removes terminal α-L-fucose residues from glycoproteins, is downregulated in some high malignancy cancers. The expression profile of FUCA1 in head and neck tumors remains unknown, and we analyzed the expression profiles of FUCA1 and an upstream molecule p53 in mucoepidermoid carcinoma (MEC) and oral squamous cell carcinoma (OSCC). FUCA1 was expressed in most MECs irrespective of histopathological grading, whereas expression in OSCCs was low. High immunohistochemical intensity of p53 was detected in OSCCs at high frequency, but rarely detected in MECs. Genetic mutation analysis using next-generation sequencing revealed no significant mutation of TP53 in MECs. We further analyzed the expression profiles of FUCA1 in normal major and minor salivary glands and found strong expression in the intercalated duct, moderate expression in mucous acinar cells and no expression in serous acinar cells. These contrasting immunohistochemical profiles and anatomical distribution in normal salivary glands suggest that FUCA1 is a useful marker to distinguish MEC from OSCC, and many MECs have similar immunohistochemical phenotypes to intercalated duct and mucous acinar cells.

Early prediction of liver carcinogenicity due to occupational exposure to pesticides.

Several studies linked between pesticides exposure and development of liver cancer, through several mechanisms inform of genotoxicity, cytotoxicity, tumor promotion, immunotoxicity and hormonal actions. This study aimed to estimate novel biomarkers for early prediction of liver malignancy due to occupational exposure to pesticides in two groups of workers with different socioeconomic standard (highly educated urban researchers and low educated rural pesticides sprayers). This study included 50 urban researchers and 50 rural pesticides sprayers occupationally exposed to pesticides. They were compared with 50 non-exposed urban researchers and 50 non-exposed rural subjects. Several tumor biomarkers were estimated; P53 protein, Alfa fetoprotein (AFP), and Alpha-L-fucosidase (AFU). Additionally, telomerase enzyme activity, Relative telomere length (RTL), and DNA damage using comet assay were measured. Furthermore, the glutathione-S-Transferase (GST) gene polymorphisms were identified for both exposed groups. Statistical analysis revealed elevated level of tumor biomarkers among exposed subjects relative to control groups in spite of being within the normal range. Increase in the DNA damage was detected, with shortening of telomere length and decrease in telomerase enzyme activity in pesticides-exposed subjects compared to their controls. Most of these changes were related to the levels of butyrylcholinesterase. Subjects with GSTT1 genotype were suggested to be more susceptible to hepatic carcinogenicity. Telomere relative length and comets assay together with GST genes polymorphisms could be used as early predictors for liver cancer susceptibility among pesticides exposed workers.

Comparing Cyclophellitol N-Alkyl and N-Acyl Cyclophellitol Aziridines as Activity-Based Glycosidase Probes.

The synthesis and evaluation as activity-based probes (ABPs) of three configurationally distinct, fluorescent N-alkyl cyclophellitol aziridine isosteres for profiling GH1 ß-glucosidase (GBA), GH27 α-galactosidase (GLA) and GH29 α-fucosidase (FUCA) is described. In comparison with the corresponding acyl aziridine ABPs reported previously, the alkyl aziridine ABPs are synthesized easily and are more stable in mild acidic and basic media, and are thus easier to handle. The ß-glucose-configured alkyl aziridine ABP proves equally effective in labeling GBA as its N-acyl counterpart, whereas the N-acyl aziridines targeting GLA and FUCA outperform their N-alkyl counterparts. Alkyl aziridines can therefore be an attractive alternative in retaining glycosidase ABP design, but in targeting a new retaining glycosidase both N-alkyl and N-acyl aziridines are best considered at the onset of a new study.

Evaluation of serum and salivary total sialic acid and α-l-fucosidase in patients with oral precancerous conditions and oral cancer.

OBJECTIVES: We compared serum and salivary total sialic acid/total protein (TSA/TP) ratios and α-l-fucosidase activity in patients with oral precancerous conditions (OPCs) and oral cancer to better understand the utility of saliva, in monitoring early changes occurring during oral cancer progression. STUDY DESIGN: A cross-sectional study of 100 oral cancer patients, 50 patients with OPC, and 100 controls was performed. RESULTS: Serum and salivary TSA/TP ratios and α-l-fucosidase activity were significantly higher in OPC and oral cancer patients compared to the controls. Also, levels were higher in controls and oral cancer patients with tobacco habits as compared to those without tobacco habits. CONCLUSION: Salivary TSA/TP ratio and α-l-fucosidase activity were elevated with higher magnitude than serum levels. These results suggest that a larger study may prove the use of these saliva biomarkers as a noninvasive method for detecting early changes occurring during oral carcinogenesis.

Synthesis of fluorescent Ag nanoclusters and their application in α-L-fucosidase detection.

Highly fluorescent Ag nanoclusters (NCs) were successfully prepared by a simple and nontoxic approach, and the as-prepared Ag NCs could be utilized for the AFu detection with a lower detection limit of 0.001 U L(-1).

Novel fluorescence method for detection of α-L-fucosidase based on CdTe quantum dots.

The enzyme α-L-fucosidase (AFu) plays an important role in the diagnosis of hepatocellular carcinoma (HCC) and fucosidosis. In this paper, a simple, sensitive and precise method based upon measuring the fluorescence quenching of CdTe semiconductor quantum dots (QDs) was developed for detecting the enzymatic activity of AFu. The detection limit of AFu was 0.01 U/L (n = 3) and the linear relationship was 0.01-4 U/L. The selectivity experiment indicated excellent selectivity for AFu over a number of interfering species. We have also studied the detection mechanism of AFu by X-ray photoelectron spectroscopy (XPS) and found that the quenching effect was caused by the oxidation of tellurium by 2-chloro-4-nitrophenol (2-CNP) which produced in AFu catalytic reaction. Moreover, the AFu sensor based on QDs was used satisfactorily for the assessment of AFu activity in serum samples. It will most probably be applicable in assembling diagnostic microdevice to realize the rapid clinic analysis of AFu.

Determination of glycosidase activity in porcine oviductal fluid at the different phases of the estrous cycle.

Sperm-oocyte binding and gamete-oviductal epithelium interactions are carbohydrate-mediated events occurring in the oviductal fluid (OF). Thus, knowledge about the activities of glycosidases (enzymes catalyzing hydrolytic cleavage of terminal sugar residues) in this milieu would help us understand the molecular mechanisms involved in these events. This work was carried out to investigate the glycosidase activity, protein content, and volume of OF collected from gilts and sows. Oviducts were classified into four phases of the estrous cycle (early follicular, late follicular, early luteal, and late luteal) based on the appearance of the ovaries. OF was aspirated, centrifuged, measured for volume, and frozen until assay. Substrates conjugated to 4-methylumbelliferyl were used to screen the activities of seven different glycosidases at physiological pH (7.2). alpha-L-Fucosidase and beta-N-acetyl-glucosaminidase activities increased at the late follicular phase to decrease after ovulation. beta-D-Galactosidase, alpha-D-mannosidase, and beta-N-acetyl-galactosaminidase showed higher activities at the early follicular phase, which decreased after ovulation. N-Acetyl-neuraminidase and alpha-D-galactosidase did not show activity at any phase of estrous cycle neither in sows nor in gilts at pH 7.2, although it did at acidic pH (4.4) in the follicular and luteal phase samples. Total protein also changed during the cycle showing the maximum secretion at the late follicular phase (2118.6+/-200.7 microg/oviduct). The highest volumes of OF were collected from the oviducts at the late follicular phase (50.7+/-1.3 microl/oviduct). These results indicate that OF from sows and gilts shows glycosidase activity varying throughout the estrous cycle suggesting a role of these enzymes in carbohydrate-mediated events.

Structural characterization of the nonameric assembly of an Archaeal alpha-L-fucosidase by synchrotron small angle X-ray scattering.

alpha-l-Fucosidase is a lysosomal enzyme responsible for hydrolyzing the alpha-1,6-linked fucose joined to the reducing-end N-acetylglucosamine of carbohydrate moieties in glycoproteins. The first alpha-l-fucosidase from Archaea was recently identified in the genome of the hyperthermophile Sulfolobus solfataricus; the enzyme is encoded by two open reading frames separated by a -1 frameshift. A preliminary biochemical and biophysical characterization of this extremophile enzyme has been carried out both in solution, through small angle X-ray scattering experiments, and in the crystalline state, showing an unusual oligomeric assembly resulting from the association of nine subunits, endowed with 3-fold molecular symmetry.

Cell surface human alpha-L-fucosidase.

The acid alpha-L-fucosidase is usually found as a soluble component of lysosomes where fucoglycoconjugates are degraded. In the present investigation, we have demonstrated the existence of a cell surface protein with enzymatic alpha-L-fucosidase activity that crossreacts specifically with a rabbit anti-(alpha-L-fucosidase) Ig. By different approaches, this alpha-L-fucosidase, which represents 10-20% of the total cellular fucosidase activity, was detected in all the tested human cells (hemopoietic, epithelial, mesenchymal). Two bands of approximately 43-49 kDa were observed, although theoretical data support the possibility of having the same genetic origin that the known 50 to 55-kDa Mr alpha-L-fucosidase. We speculate about an alternative traffic pathway for the plasma membrane alpha-L-fucosidase to work on the rapid turnover of glycoproteins.

[Combined five tumor markers in detecting primary hepatic carcinoma].

OBJECTIVE: To increase the detection rate of primary hepatic carcinoma (PHC) and to diagnose PHC earlier. METHODS: AFP was combined with r-glutamyle transpeptidase (r-GT), alpha-fucosidase (AFU), tumor necrosis factor-alpha (TNF-alpha) and DR-70. RESULTS: The positive detection rate of PHC negative AFP with combined four markers was 9.4%. The total positive detection rate of PHC with combined five tumor markers reached 98.0% which was significantly higher than that with AFP (P < 0.01). CONCLUSIONS: The positive detection rate of PHC can be increased by combined five tumor markers. It is helpful in diagnosing PHC earlier and can differentiate PHC from liver cirrhosis.

Characterization of human semen alpha-L-fucosidases.

Human semen contains a large amount of alpha-L-fucosidase activity, the great majority of which is found in the seminal fluid. Immunocytochemical studies indicate that a small amount of semen fucosidase activity is present on the sperm plasma membrane, primarily in the posterior head region. Subcellular fractionation studies also indicate that sperm alpha-L-fucosidase is present in the plasma membrane-enriched fraction. Comparative characterization of human seminal fluid and sperm alpha-L-fucosidases indicates that seminal fluid alpha-L-fucosidase has a broad pH optimum curve with a number of near-equal maxima between pH 4.8 and 7.0 while sperm fucosidase has a major optimum between pH 3.4 and 4.0. Isoelectric focusing indicates that seminal fluid alpha-L-fucosidase contains three to six isoforms with isoelectric points (pI) of 5-7 while sperm fucosidase contains two distinct isoforms with pI values of 5. 2 +/- 0.2 and 7.0 +/- 0.2. Western blotting indicates that seminal fluid fucosidase contains a major protein band with a molecular mass ratio (M(r)) of approximately 56 kDa while sperm fucosidase contains a major protein band of approximately 51 kDa. The overall results indicate the presence of a low-abundance, plasma membrane-associated human sperm alpha-L-fucosidase, which is different in its properties from human seminal fluid alpha-L-fucosidase(s), and whose function is not yet known.

Serum and pleural fluid levels of alpha-L-fucosidase and sialic acid have no diagnostic value in malignant pleural effusions.

The association of biological markers with cancer has been recognized for many decades. To determine whether alpha-L-fucosidase (ALF) and sialic acid (SA) are sensitive markers in malignant pleural effusions, they were investigated in serum and pleural fluid of 64 consecutive pleurisy patients, and in serum of 23 healthy subjects as a control group. The serum ALF (sALF) and serum SA (sSA) values of malignant and nonmalignant groups were higher than that of the control group, but the differences were statistically significant only for sSA determinations (p < 0.05). Values of sALF, sSA, pleural ALF (pALF), and pleural SA (pSA) were higher in the malignant group than the nonmalignant group, but no significant difference was found between the two groups. In conclusion, neither alpha-L-fucosidase nor sialic acid will be useful in the detection of malignant pleural effusions.

Compartmentalization of fucosyltransferase and alpha-L-fucosidase in human milk.

Several pathogenic agents of pediatric gastroenteritis are inhibited by fucosylated oligosaccharides of human milk. Biosynthesis and degradation of fucosyloligosaccharides is controlled by fucosyltransferase and alpha-L-fucosidase. The activity of these enzymes varies reciprocally over the course of lactation. We hypothesized that differences in the specific organization of these enzymes in compartments of human milk might contribute to such differences in activity. Therefore, the distribution of these enzymes in various compartments of human milk was investigated. After ultracentrifugation at 120,000g for 2h, the fucosyltransferase activity distributes evenly between the supernatant and the membranous pellet. Ultracentrifugation at 180,000g for 17 h further fractionated the milk into a clear supernatant, a fluff layer from the supernatant, and a pellet. The fluff was visualized by electron microscopy. The distribution of fucosyltransferase activity in colostrum was compared with that of mature milk from the same donor. In mature milk from Day 30 of lactation, most fucosyltransferase activity was in the membranous fluff fraction, while in colostrum from Day 5 of lactation, most of the fucosyltransferase activity was in the supernatant. In contrast to fucosyltransferase, fucosidase activity was found only in the soluble milk fraction; upon prolonged ultracentrifugation, most of this was membrane associated. The nature of human milk fucosidase was studied. This enzyme is glycosylated and exhibits several characteristics common to other fucosidases. Under the conditions found in human milk, it exhibits almost full activity. The variation in compartmentalization of fucosyltransferase activity during lactation may reflect variations in metabolism of the fucosyloligosaccharides of human milk that protect against disease.

Nonradioactive immunoquantification of alpha-L-fucosidase protein in human colon tissues.

alpha-L-Fucosidase is a glycosidase involved in the degradation of fucoglycoconjugates and has a diagnostic significance because it has been described to be altered in several known diseases. However, in vitro studies on enzymatic activities may not reflect the real protein levels in tissues. This paper describes a simple method to quantify alpha-L-fucosidase protein levels in human crude extracts, combining the slot-blot technique and a nonradioactive immunoassay. Taking advantage of the similarities in different mammalian fucosidases, a polyclonal antiserum was raised against commercial purified alpha-L-fucosidase from bovine kidney that cross-reacted with the human colon enzyme. The method is able to detect as little as 0.75 ng alpha-L-fucosidase. To illustrate the direct application of this technique, we analysed and quantified alpha-L-fucosidase protein levels in 18 human colon crude samples. This technique could prove useful in clinical pathology, allowing fast and accurate measurement of alpha-L-fucosidase in crude extracts.

Diagnosis of I-cell disease.

I-cell disease (mucolipidosis II) is a rare lysosomal storage disease, with its primary defect the deficiency of an enzyme responsible for lysosomal enzyme processing, resulting in multiple lysosomal enzyme insufficiency. Diagnosis of I-cell disease usually can be made by the specific patterns of enzyme distribution: deficient intracellular, but excessive extracellular, enzymes. A six month old female infant was found to have bilateral congenital dislocation of hips, developmental delay, coarsening of facial appearance and dysostosis multiplex. In view of the very early onset of disease, I-cell disease was suspected. Lysosomal enzyme tests (including alpha-mannosidase, alpha-fucosidase, beta-glucuronidase and beta-galactosidase) were performed on the leukocytes, skin fibroblasts, plasma and media from fibroblast cultures. All activities of the four enzymes were low in both leukocytes and fibroblasts, but were 10- to 70-fold higher than normal in plasma, and high in culture media. Both the clinical and laboratory findings here were consistent with a diagnosis of I-cell disease.

Biochemical and histochemical analysis of lysosomal enzyme activities in caprine beta-mannosidosis.

Goats affected with beta-mannosidosis, an autosomal recessive disease of glycoprotein catabolism, have deficient tissue and plasma levels of the lysosomal enzyme beta-mannosidase. Pathological characteristics include cytoplasmic vacuolation in the nervous system and viscera, and myelin deficits that demonstrate regional variation. This study was designed to determine the correlation between beta-mannosidase activity in normal animals and the severity of lesions in affected goats, and to assess the regional changes in lysosomal enzyme activity in specific regions and cell types in affected animals. Although enzyme activity in normal organs (kidney, thyroid, brain) is correlated in general with the accumulation of uncatabolized substrate and with the extent of vacuolation, this correlation does not extend to assessment of specific regions of the central nervous system (CNS). In affected goats, the activities of alpha-mannosidase, alpha-fucosidase, and beta-hexosaminidase are elevated to a greater extent in all CNS regions than in organs. The results suggest cell-specific, organ-specific, and enzyme-specific regulation of changes in lysosomal enzyme activity in the presence of metabolic perturbations, such as deficiency of beta-mannosidase activity.