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X L Li

Publications and source records attributed to X L Li.

At least 55 records · Page 3Linked to original sources
PubMed2001

Noncatalytic docking domains of cellulosomes of anaerobic fungi.

A method is presented for the specific isolation of genes encoding cellulosome components from anaerobic fungi. The catalytic components of the cellulosome of anaerobic fungi typically contain, besides the catalytic domain, mostly two copies of a 40-amino-acid cysteine-rich, noncatalytic docking domain (NCDD) interspaced by short linkers. Degenerate primers were designed to anneal to the highly conserved region within the NCDDs of the monocentric fungus Piromyces sp. strain E2 and the polycentric fungus Orpinomyces sp. strain PC-2. Through PCR using cDNA from Orpinomyces sp. and genomic DNA from Piromyces sp. as templates, respectively, 9 and 19 PCR products were isolated encoding novel NCDD linker sequences. Screening of an Orpinomyces sp. cDNA library with four of these PCR products resulted in the isolation of new genes encoding cellulosome components. An alignment of the partial NCDD sequence information obtained and an alignment of database-accessible NCDD sequences, focusing on the number and position of cysteine residues, indicated the presence of three structural subfamilies within fungal NCDDs. Furthermore, evidence is presented that the NCDDs in CelC from the polycentric fungus Orpinomyces sp. strain PC-2 specifically recognize four proteins in a cellulosome preparation, indicating the presence of multiple scaffoldins.

Amino Acid Sequence↗
PubMed2001

Properties and mutation analysis of the CelK cellulose-binding domain from the Clostridium thermocellum cellulosome.

The family IV cellulose-binding domain of Clostridium thermocellum CelK (CBD(CelK)) was expressed in Escherichia coli and purified. It binds to acid-swollen cellulose (ASC) and bacterial microcrystalline cellulose (BMCC) with capacities of 16.03 and 3.95 micromol/g of cellulose and relative affinities (K(r)) of 2.33 and 9.87 liters/g, respectively. The CBD(CelK) is the first representative of family IV CBDs to exhibit an affinity for BMCC. The CBD(CelK) also binds to the soluble polysaccharides lichenin, glucomannan, and barley beta-glucan, which are substrates for CelK. It does not bind to xylan, galactomannan, and carboxymethyl cellulose. The CBD(CelK) contains 1 mol of calcium per mol. The CBD(CelK) has three thiol groups and one disulfide, reduction of which results in total loss of cellulose-binding ability. To reveal amino acid residues important for biological function of the domain and to investigate the role of calcium in the CBD(CelK) four highly conserved aromatic residues (Trp(56), Trp(94), Tyr(111), and Tyr(136)) and Asp(192) were mutated into alanines, giving the mutants W56A, W94A, Y111A, Y136A, and D192A. In addition 14 N-terminal amino acids were deleted, giving the CBD-N(CelK). The CBD-N(CelK) and D192A retained binding parameters close to that of the intact CBD(CelK), W56A and W94A totally lost the ability to bind to cellulose, Y136A bound to both ASC and BMCC but with significantly reduced binding capacity and K(r) and Y111A bound weakly to ASC and did not bind to BMCC. Mutations of the aromatic residues in the CBD(CelK) led to structural changes revealed by studying solubility, circular-dichroism spectra, dimer formation, and aggregation. Calcium content was drastically decreased in D192A. The results suggest that Asp192 is in the calcium-binding site of the CBD(CelK) and that calcium does not affect binding to cellulose. The 14 amino acids from the N terminus of the CBD(CelK) are not important for binding. Tyr136, corresponding to Cellulomonas fimi CenC CBD(N1) Y85, located near the binding cleft, might be involved in the formation of the binding surface, while Y111, W56A, and W94A are essential for the binding process by keeping the CBD(CelK) correctly folded.

Amino Acid Sequence↗
PubMed2001

Role for p53 in gene induction by double-stranded RNA.

Cross talk between p53 and interferon-regulated pathways is implicated in the induction of gene expression by biologic and genotoxic stresses. We demonstrate that the interferon-stimulated gene ISG15 is induced by p53 and that p53 is required for optimal gene induction by double-stranded RNA (dsRNA), but not interferon. Interestingly, virus induces ISG15 in the absence of p53, suggesting that virus and dsRNA employ distinct signaling pathways.

Animals↗
PubMed2001

Relationship between phenotypes of cell-function differentiation and pathobiological behavior of gastric carcinomas.

AIM: To reveal the correlation between the functional differentiation phenotypes of gastric carcinoma cells and the invasion and metastasis by a new way of cell-function classification. METHODS: Surgically resected specimens of 361 gastric carcinomas(GC) were investigated with enzyme-, mucin-, and tumor-related marker immunohistochemistry. According to the direction of cell-function differentiation, stomach carcinomas were divided into five functionally differentiated types. RESULTS: (1) Absorptive function differentiation type (AFDT): there were 82 (22.7%) patients including 76 (92.7%) aged 45 years. Sixty-nine (84.1%) cases belonged to the intestinal type. Thirty-eight (46.3%) expressed CD44v6 and 9 (13.6%) of 66 male patients developed liver metastasis. The 5-year survival rate of patients in this group (58.5%) was higher than those with the other types (P<0.01). (2) Mucin secreting function differentiation type (MSFDT): 54 (15%) cases. Fifty-three (98.1%) tumors had penetrated the serosa, 12 (22.2%) expressed ER and 22 (40.7%) expressed CD44v6. The postoperative 5-year survival rate was 28.6%. (3) Absorptive and mucin-producing function differentiation type (AMPFDT): there were 180 (49.9%) cases, including 31 (17.2%) aged younger than 45 years. The tumor was more common in women (62, 34.4%,) and expressed more frequently estrogen receptors (ER) (129, 81.7%) than other types (P<0.01). Ovary metastasis was found in 12 (19.4%) out of 62 female subjects. The patients with this type GC had the lowest 5-year survival rate (24.7%) among all types. (4) Specific function differentiation type (SFDT): 13 (3.6%) cases. Nine (69.2%) tumors of this type derived from APUD system, the other 4 (30.7%) were of different histological differentiation. Sixty per cent of the patients survived at least five years. (5) Non-function differentiation type (NFDT): 32 (8.9%) cases. Nineteen (59.4%) cases had lymph node metastases but no one with liver or ovary metastasis. The 5-year survival rate was 28.1%. CONCLUSION: This new cell-function classification of GC is helpful in indicating the characteristics of invasion and metastasis of GC with different cell-function differentiation phenotypes. Further study is needed to disclose the correlation between the cell-functional differentiation phenotypes and the relevant genotypes and the biological behavior of gastric carcinoma.

Biomarkers, Tumor↗
PubMed2001

Tibetan population data on the multiplex short tandem repeat loci--D16S539, D7S820, and D13S317.

The multiplex amplification system of three tetrameric short tandem repeats loci (D16S539, D7S820, and D13S317) have been analysed extensively in various populations for forensic application. Population genetic studies were carried out for these three loci in a population sample of 129 unrelated Tibetan individuals by using a multiplex polymerase chain reaction (PCR) followed by 4% polyacrylamide gel electrophoresis (PAGE) and silver staining. All loci were in accordance with the Hardy-Weinberg expectations. The observed heterozygosities of three loci-D16S539, D7S820, and D13S317 were 73.3%, 81.4% and 80.6%, respectively. The polymorphism information contents (PIC) were 0.84, 0.80 and 0.83, respectively. Comparing with Han population, there was no statistically significant difference except for D16S539 locus.

Chromosome Mapping↗
PubMed2001

[Differential expression of genes in the pigeon forebrain after removal of the left retina].

Suppression subtractive hybridization (SSH) was used to analyze differential expression of genes in the pigeon forebrain after the left retina of the pigeon was removed at hatching. Four genes out of the 14 identified clones produced positive hybridization signals as shown by reverse Northern blot. Sequencing results showed that the length of PFB/SSH-8 is 226 bp, of which 138 bp produced a homology of 85% with human CaMI; the length of PFB/SSH-15 is 252 bp, showing low homology with nexin I alpha; no matched homological information was found in the remaining 2 clones.

Animals↗
PubMed2001

Isolation of ovulation-inducing factors in the seminal plasma of Bactrian camel (Camelus bactrianus) by DEAE-cellulose chromatography.

Ovulation in the Bactrian camel (Camelus bactrianus) depends upon the ovulation-inducing factor in the seminal plasma; however, little research has been conducted to isolate and identify the factor. The current study attempts to isolate and identify the bioactive fractions from the seminal plasma of Bactrian camel. The seminal plasma was fractionated by diethylamino-ethylcellulose (DEAE)-cellulose chromatography and five protein fractions were obtained. The bioactive of each fraction was estimated by rat pituitary tissue culture in vitro and by the intramuscular injection of the bioactive fraction to the female camels in vivo. The concentrations of luteinizing hormone (LH) and follicle-stimulating hormone (FSH) in the pituitary culture media before and 6 h after the addition of each fraction and in the peripheral blood plasma collected from the camel immediately before and hourly after the injection of the active fraction were measured by radioimmunoassay. The results demonstrated that the third fraction (L3) had the bioactive potential to stimulate the release of LH in vitro from 11.82 +/- 1.77 to 25.63 +/- 3.84 mIU/ml after the addition of L3 to the culture media. The in vivo concentrations of LH in the blood plasma of the camel increased from 6.43 +/- 0.14 before to 15.50 +/- 2.64 ng/ml 6 h after injection of L3. However, the concentrations of FSH did not show any significant changes either in vitro or in vivo. The results clearly demonstrated the existence of LH-releasing associated fractions in the seminal plasma that appears to be separated by DEAE-cellulose matrix and the isolated L3 fraction might be the ovulation-inducing factor or one of its components.

Animals↗
PubMed2001

[Cloning and expression of human anti-colonic cancer single-chain Fv fragment].

We report a new strategy for the generation of human anticolon cancer monoclonal antibodies based on the molecular cloning and expression of immunoglobulin variable region cDNAs derived from peripheral blood mononuclear cells (PBMC) that were transformed by EBV. The immortalized B cells secreting tumor-specific antibodies were identified by HRT-18 cell ELISA and cloned by limiting dilution. Heavy- and light-chain VH-CH1 (gamma) and V kappa-C kappa cDNAs were rescued from ELISA-positive cells wells by RT-PCR. VH and V kappa were amplified by 2nd PCR and linked them together by 3rd PCR assembly with the use of a (Gly4Ser)3 linker. The ScFv cDNAs were then cloned into the fUSE 5 vector and displayed on phage. Phage clones were selected on HRT-18 cells and normal human PBMC. ELISA tested phage clones randomly picked after each panning step. > 80% of the clones showed a strong ELISA reaction, demonstrating the effectiveness of the panning procedure for selecting anticolon cancer antibodies. This approach offers an effective method by combining in vitro immunization, B-cell expansion for enrichment of specific B-lymphocytes, PCR gene cloning and phage display to make high-affinity human anticolon cancer monoclonal antibody molecules.

Antibodies, Monoclonal↗
PubMed2001

[Prophylaxis for deep vein thrombosis with low molecular weight heparin following hip and knee surgery].

OBJECTIVE: To evaluate the efficacy and safety of low molecular weight heparin(LMWH) in prophylaxis of postoperative deep vein thrombosis (DVT) following hip and knee surgery. METHODS: From April 1997 to October 1998, 46 patients undergoing hip and knee orthopedic procedures were randomized into 2 groups for studying. The following eligibility criteria were applied: age over 40 years old, no recently history of venous thromboembolism (over 3 months), normal result of preoperative hemostasis test and normal result of Doppler examination of the lower extremities. One group was control group and the other group received subcutaneously a low molecular weight heparin(Fraxiparine) with anti-factor X, activity of 41 IU/kg.day for three days, then 62 IU/kg.day from the 4th day to 10th day. All patients had venegraphy performed in the operated leg at 4 to 7 days after surgery. RESULTS: eight patients(34.8%) developed DVT in the control group of 23 patients and 1 patient (4.3%) in the experimental group, also of 23 patients(P < 0.05). Two groups had no any bleeding complications. CONCLUSION: The low molecular weight heparin is safe and effective in preventing postoperative deep vein thrombosis in patients following hip and knee surgery.

Adult↗
PubMed2001

[Cloning and identification of deltamethrin-resistance or susceptibility associated genes of Culex pipiens pallens].

OBJECTIVE: To obtain deltamethrin-resistance or susceptibility associated genes of Culex pipiens pallens. METHODS: The differentially expressed genes were obtained by suppression subtractive hybridization (SSH), and identified by cDNA microarray and reverse Northern blotting. RESULTS: 523 and 286 clones were selected respectively in the two directional SSH. 155 and 42 genes were respectively expressed 2-3 and > 3 times higher in the insecticide-resistant strain than in the susceptible strain; 15 and 9 genes were respectively expressed 2-3 and > 3 times higher in the susceptible strain than in the resistant strain. There were 2 genes only expressed in the insecticide-resistant strain. 51 three times differentially expressed clones and 2 specially expressed clones were sequenced. 44 sequences were obtained which belong to 13 new genes. There were 8 over-expressed genes in resistant strain, 7 of which were similar respectively to mitochondrion rRNA gene, 60S ribosomal protein gene, 40S ribosomal protein S4 gene, trypsin gene, chymotrypsin A gene, ospin gene, and 16S ribosomal RNA gene. There were 5 over-expressed genes in susceptible strain, 2 of them being similar with 40S ribosomal protein S29 gene and myosin regulatory light chain 2 gene. In addition, 2 genes specially expressed in resistant strain were similar respectively to glycogen branching enzyme gene and ribosomal protein 46 gene. CONCLUSION: The differentially expressed genes may be associated with deltamethrin-resistance or susceptibility of Culex pipiens pallens.

Animals↗
PubMed2000

RNase-L-dependent destabilization of interferon-induced mRNAs. A role for the 2-5A system in attenuation of the interferon response.

The 2-5A system is an interferon-regulated RNA degradation pathway with antiviral, growth-inhibitory, and pro-apoptotic activities. RNase-L mediates the antiviral activity through the degradation of viral RNAs, and the anticellular effects of the 2-5A system are thought to be similarly mediated through the degradation of cellular transcripts. However, specific RNase-L-regulated cellular RNAs have not been identified. To isolate candidate RNase-L substrates, differential display was used to identify mRNAs that exhibited increased expression in RNase-L-deficient N1E-115 cells as compared with RNase-L-transfected cells. A novel interferon-stimulated gene encoding a 43-kDa ubiquitin-specific protease, designated ISG43, was identified in this screen. ISG43 expression is induced by interferon and negatively regulated by RNase-L. ISG43 induction is a primary response to interferon treatment and requires a functional JAK/STAT signaling pathway. The kinetics of ISG43 induction were identical in wild type and RNase-L knock-out fibroblasts; however, the decline in ISG43 mRNA following interferon treatment was markedly attenuated in RNase-L knock-out fibroblasts. The delayed shut-off kinetics of ISG43 mRNA corresponded to an increase in its half-life in RNase-L-deficient cells. ISG15 mRNA also displayed RNase-L-dependent regulation. These findings identify a novel role for the 2-5A system in the attenuation of the interferon response.

Amino Acid Sequence↗
PubMed2000

Tolerance to the anticonvulsant effects of lamotrigine on amygdala kindled seizures: cross-tolerance to carbamazepine but not valproate or diazepam.

Using an amygdala-kindled seizure paradigm, we evaluated the acute and chronic anticonvulsant effects of lamotrigine (LTG). Lamotrigine produced dose-dependent inhibitory effects on seizure stage, afterdischarge (AD), and seizure duration. Lamotrigine (15 mg/kg) also increased the afterdischarge and seizure thresholds. Following repeated LTG administration and stimulation at 48-h intervals, tolerance developed to LTG's (15 mg/kg) anticonvulsant effects, and cross-tolerance was observed to the anticonvulsant effects of carbamazepine (CBZ, 15 mg/kg). In a separate group of kindled rats, CBZ (15 mg/kg) was repeatedly administered to induce tolerance. This led to a partial cross-tolerance to LTG, manifesting as an increased rate of tolerance development to LTG, and seizures following the first injection in some animals, which were not observed in CBZ-nontolerant controls. When these rats were made fully tolerant to LTG and then exposed to higher doses of LTG (30 and 50 mg/kg), no anticonvulsant effects were observed. In contrast, higher doses of CBZ (30 mg/kg) did restore efficacy in CBZ-tolerant animals. Cross-tolerance from LTG to valproate and diazepam was not observed, although cross-tolerance from CBZ to valproate has been reported previously. These data suggest that LTG has both shared and distinct anticonvulsant mechanisms from those of CBZ on amygdala-kindled seizures. The implications of these results for clinical therapeutics remain to be evaluated.

Amygdala↗
PubMed2000

Lamotrigine treatment during amygdala-kindled seizure development fails to inhibit seizures and diminishes subsequent anticonvulsant efficacy.

PURPOSE: Lamotrigine (LTG) is an anticonvulsant that is currently in use for the treatment of various seizure disorders and that shows promise in the treatment of affective illness. LTG is also effective in the suppression of amygdala-kindled seizures. Because many drugs show a differential efficacy profile as a function of the phase of kindling evolution, we evaluated LTG for its potential antiepileptogenic effects on the development of amygdala-kindled seizures. METHODS: In two separate studies, LTG (5 or 15 mg/kg versus vehicle) was administered before each daily amygdala stimulation (biphasic square wave pulses, 100 pulse pairs per second for a total of 0.5 second, 1-millisecond pulse width) at an intensity of 50 microA over the AD threshold. Seizure development was assessed, as well as the effect of this pretreatment on subsequent efficacy of LTG on completed kindled seizures. RESULTS: LTG at 5 mg/kg failed to block seizure development. At 15 mg/kg, LTG paradoxically enhanced seizure development and produced running fits in four of the nine animals tested. Animals previously treated with either dose of LTG during kindling development showed a diminished response to the anticonvulsant effects of LTG on fully kindled seizures compared with the vehicle-treated controls. CONCLUSIONS: Although LTG possesses potent anticonvulsant effects on completed amygdala-kindled seizures, it is either without effect (5 mg/kg) or facilitates (15 mg/kg) the initial phase of kindling development. In addition, exposure to LTG during kindled seizure development leads to a reduced subsequent response to the drug in fully kindled animals. These observations parallel those with carbamazepine and suggest that different stages of kindling (epileptogenesis versus fully manifest seizures) may have different underlying neural mechanisms that require distinct pharmacotherapies.

Amygdala↗
PubMed2000

Feruloyl esterase activity of the Clostridium thermocellum cellulosome can be attributed to previously unknown domains of XynY and XynZ.

The cellulosome of Clostridium thermocellum is a multiprotein complex with endo- and exocellulase, xylanase, beta-glucanase, and acetyl xylan esterase activities. XynY and XynZ, components of the cellulosome, are composed of several domains including xylanase domains and domains of unknown function (UDs). Database searches revealed that the C- and N-terminal UDs of XynY and XynZ, respectively, have sequence homology with the sequence of a feruloyl esterase of strain PC-2 of the anaerobic fungus Orpinomyces. Purified cellulosomes from C. thermocellum were found to hydrolyze FAXX (O-(5-O-[(E)-feruloyl]-alpha-L-arabinofuranosyl)-(1-->3)-O-beta-D- xyl opyranosyl-(1-->4)-D-xylopyranose) and FAX(3) (5-O-[(E)-feruloyl]-[O-beta-D-xylopyranosyl-(1-->2)]-O-alpha-L- arabinofuranosyl-[1-->3])-O-beta-D-xylopyranosyl-(1-->4)-D-xylopyranose) , yielding ferulic acid as a product, indicating that they have feruloyl esterase activity. Nucleotide sequences corresponding to the UDs of XynY and XynZ were cloned into Escherichia coli, and the expressed proteins hydrolyzed FAXX and FAX(3). The recombinant feruloyl esterase domain of XynZ alone (FAE(XynZ)) and with the adjacent cellulose binding domain (FAE-CBD(XynZ)) were characterized. FAE-CBD(XynZ) had a molecular mass of 45 kDa that corresponded to the expected product of the 1,203-bp gene. K(m) and V(max) values for FAX(3) were 5 mM and 12.5 U/mg, respectively, at pH 6.0 and 60 degrees C. PAX(3), a substrate similar to FAX(3) but with a p-coumaroyl group instead of a feruloyl moiety was hydrolyzed at a rate 10 times slower. The recombinant enzyme was active between pH 3 to 10 with an optimum between pH 4 to 7 and at temperatures up to 70 degrees C. Treatment of Coastal Bermuda grass with the enzyme released mainly ferulic acid and a lower amount of p-coumaric acid. FAE(XynZ) had similar properties. Removal of the 40 C-terminal amino acids, residues 247 to 286, of FAE(XynZ) resulted in protein without activity. Feruloyl esterases are believed to aid in a release of lignin from hemicellulose and may be involved in lignin solubilization. The presence of feruloyl esterase in the C. thermocellum cellulosome together with its other hydrolytic activities demonstrates a powerful enzymatic potential of this organelle in plant cell wall decomposition.

Amino Acid Sequence↗
PubMed2000

[Cloning and identification of cytochrome P450 resistance related genes in the mosquito, Culex pipiens pallens].

OBJECTIVE: To inquire into the relationship between cytochrome P450 and deltamethrin resistance. METHODS: 24 new cDNA sequences encoding cytochrome P450 were amplified respectively from deltamethrin-susceptible and -resistant strains of Culex pipiens pallens with a pair of degenerate primers according to the conservative amino acid sequences of CYP4 in insects by RT-PCR and the Direct Cloning Method, and then were identified by cDNA chip and reverse Northern. RESULTS: 112 positive clones were obtained, of which 24 were shown to be new sequences encoded for cytochrome P450. They have been lodged in GenBank and were appraised by the Nomenclature Committee of Cytochrome P450, belonging to the subfamily CYP4C, CYP4D, CYP4H and CYP4J in CYP4 family. The hybrid signal values of 6 P450 sequences (NYDS3, NYDS5, NYDR6, NYDR9, NYDR15 and NYDR17) were 3.1-9.7 times higher in the resistance probe than in the susceptible probe, and NYDR17 only reacted with the resistance probe. The result of reverse Northern in NYDR15 was similar to that of cDNA chip. CONCLUSION: CYP4 is related to deltamethrin resistance and the specific expression caused by point mutation of cytochrome P450 gene may exist in deltamethrin-resistant Cx. pipiens pallens.

Animals↗
PubMed1999

Human acyl-CoA:cholesterol acyltransferase-1 (ACAT-1) gene organization and evidence that the 4.3-kilobase ACAT-1 mRNA is produced from two different chromosomes.

Acyl-CoA:cholesterol acyltransferase (ACAT) plays important roles in cellular cholesterol homeostasis. Four human ACAT-1 mRNAs (7.0, 4.3, 3.6, and 2.8 kilobases (kb)) share the same short 5'-untranslated region (exon 1) and coding sequence (exons 2-15). The 4.3-kb mRNA contains an additional 5'-untranslated region (1289 nucleotides in length; exons Xa and Xb) immediately upstream from the exon 1 sequence. One ACAT-1 genomic DNA insert covers exons 1-16 and a promoter (the P1 promoter). A separate insert covers exon Xa (1277 base pairs) and a different promoter (the P7 promoter). Gene mapping shows that exons 1-16 and the P1 promoter sequences are located in chromosome 1, while exon Xa and the P7 promoter sequence are located in chromosome 7. RNase protection assays demonstrate three different protected fragments, corresponding to the 4.3-kb mRNA and the two other mRNAs transcribed from the two promoters. These results are consistent with the interpretation that the 4.3-kb mRNA is produced from two different chromosomes, by a novel RNA recombination mechanism involving trans-splicing of two discontinuous precursor RNAs.

5' Untranslated Regions↗
PubMed1999

Characterization of an acetyl xylan esterase from the anaerobic fungus Orpinomyces sp. strain PC-2.

A 1,067-bp cDNA, designated axeA, coding for an acetyl xylan esterase (AxeA) was cloned from the anaerobic rumen fungus Orpinomyces sp. strain PC-2. The gene had an open reading frame of 939 bp encoding a polypeptide of 313 amino acid residues with a calculated mass of 34,845 Da. An active esterase using the original start codon of the cDNA was synthesized in Escherichia coli. Two active forms of the esterase were purified from recombinant E. coli cultures. The size difference of 8 amino acids was a result of cleavages at two different sites within the signal peptide. The enzyme released acetate from several acetylated substrates, including acetylated xylan. The activity toward acetylated xylan was tripled in the presence of recombinant xylanase A from the same fungus. Using p-nitrophenyl acetate as a substrate, the enzyme had a K(m) of 0.9 mM and a V(max) of 785 micromol min(-1) mg(-1). It had temperature and pH optima of 30 degrees C and 9.0, respectively. AxeA had 56% amino acid identity with BnaA, an acetyl xylan esterase of Neocallimastix patriciarum, but the Orpinomyces AxeA was devoid of a noncatalytic repeated peptide domain (NCRPD) found at the carboxy terminus of the Neocallimastix BnaA. The NCRPD found in many glycosyl hydrolases and esterases of anaerobic fungi has been postulated to function as a docking domain for cellulase-hemicellulase complexes, similar to the dockerin of the cellulosome of Clostridium thermocellum. The difference in domain structures indicated that the two highly similar esterases of Orpinomyces and Neocallimastix may be differently located, the former being a free enzyme and the latter being a component of a cellulase-hemicellulase complex. Sequence data indicate that AxeA and BnaA might represent a new family of hydrolases.

Acetylesterase↗