A candidate prostate cancer susceptibility gene at chromosome 17p.

It is difficult to identify genes that predispose to prostate cancer due to late age at diagnosis, presence of phenocopies within high-risk pedigrees and genetic complexity. A genome-wide scan of large, high-risk pedigrees from Utah has provided evidence for linkage to a locus on chromosome 17p. We carried out positional cloning and mutation screening within the refined interval, identifying a gene, ELAC2, harboring mutations (including a frameshift and a nonconservative missense change) that segregate with prostate cancer in two pedigrees. In addition, two common missense variants in the gene are associated with the occurrence of prostate cancer. ELAC2 is a member of an uncharacterized gene family predicted to encode a metal-dependent hydrolase domain that is conserved among eukaryotes, archaebacteria and eubacteria. The gene product bears amino acid sequence similarity to two better understood protein families, namely the PSO2 (SNM1) DNA interstrand crosslink repair proteins and the 73-kD subunit of mRNA 3' end cleavage and polyadenylation specificity factor (CPSF73).

A novel A10E homozygous mutation in the HSD3B2 gene causing severe salt-wasting 3beta-hydroxysteroid dehydrogenase deficiency in 46,XX and 46,XY French-Canadians: evaluation of gonadal function after puberty.

Severe 3beta-hydroxysteroid dehydrogenase (3betaHSD) deficiency is a rare form of congenital adrenal hyperplasia resulting from mutations in the HSD3B2 gene that impair steroidogenesis in both the adrenals and gonads and cause salt-wasting in both sexes and incomplete masculinization of the external genitalia in genetic males. About two thirds of the reported patients are 46,XY. We describe two French-Canadian patients from two families without a known relationship who presented with severe salt-wasting 3betaHSD deficiency in infancy. Although the diagnosis was considered clinically, plasma steroid profiles were confusing. We have thus directly sequenced DNA fragments generated by PCR amplification of the four exons, exon-intron boundaries, and the 5'-flanking regions of the HSD3B2 gene. Sequencing of exon II revealed the presence of a C to A transversion in both alleles of these two cases, thus converting codon 10 (GCA), which codes for Ala, into GAA, encoding Glu. This Ala is highly conserved in the vertebrate 3betaHSD gene family and is located in the putative NAD-binding domain of the enzyme. The mutant type II 3betaHSD enzyme carrying an A10E substitution exhibited no detectable activity in intact transfected Ad293 cells. Both homozygous patients share the same haplotype, spanning approximately 3.3 centimorgans surrounding the HSD3B2 locus, which is consistent with a founder effect for this missense mutation. The 46,XY patient presented with ambiguous genitalia at birth and underwent normal masculinization at puberty, but was azoospermic at 18.5 yr of age. The 46,XX patient presented progressive breast development, menarche, and evidence of progesterone secretion. The only previously reported cases with pubertal follow-up revealed paternity in one male and hypogonadism in one female. These findings demonstrate the complex relationships between the genotype and the gonadal phenotype in severe 3betaHSD deficiency and the difficulty in predicting fertility.

New insight into the molecular basis of 3beta-hydroxysteroid dehydrogenase deficiency: identification of eight mutations in the HSD3B2 gene eleven patients from seven new families and comparison of the functional properties of twenty-five mutant enzymes.

Classical 3beta-hydroxysteroid dehydrogenase/delta5-delta4 isomerase (3betaHSD) deficiency is a form of congenital adrenal hyperplasia that impairs steroidogenesis in both the adrenals and gonads resulting from mutations in the HSD3B2 gene and causing various degrees of salt-wasting in both sexes and incomplete masculinization of the external genitalia in genetic males. To identify the molecular lesion(s) in the HSD3B2 gene in the 11 patients from the seven new families suffering from classical 3betaHSD deficiency, the complete nucleotide sequence of the whole coding region and exon-intron splicing boundaries of this gene was determined by direct sequencing. Five of these families were referred to Morel's molecular diagnostics laboratory in France, whereas the two other families were investigated by Peter's group in Germany. Functional characterization studies were performed by Simard's group in Canada. Following transient expression in 293 cells of each of the mutant recombinant proteins generated by site-directed mutagenesis, the effect of the 25 mutations on enzyme activity was assessed by incubating intact cells in culture with 10 nM [14C]-DHEA as substrate. The stability of the mutant proteins has been investigated using a combination of Northern and Western blot analyses, as well as an in vitro transcription/translation assay using rabbit reticulocyte lysates. The present report describes the identification of 8 mutations, in seven new families with individuals suffering from classical 3betaHSD deficiency, thus increasing the number of known HSD3B2 mutations involved in this autosomal recessive disorder to 31 (1 splicing, 1 in-frame deletion, 3 nonsense, 4 frameshift and 22 missense mutations). In addition to the mutations reported here in these new families, we have also investigated for the first time the functional significance of previously reported missense mutations and or sequence variants namely, A82T, A167V, L173R, L205P, S213G and K216E, P222H, T259M, and T259R, which have not previously been functionally characterized. Furthermore, their effects have been compared with those of the 10 previously reported mutant enzymes to provide a more consistent and comprehensive study. The present results are in accordance with the prediction that no functional 3betaHSD type 2 isoenzyme is expressed in the adrenals and gonads of the patients suffering from a severe salt-wasting form of CAH due to classical 3betaHSD deficiency. Whereas the nonsalt-losing form also results from missense mutation(s) in the HSD3B2 gene, which cause an incomplete loss in enzyme activity, thus leaving sufficient enzymatic activity to prevent salt wasting. The functional data described in the present study concerning the sequence variants A167V, S213G, K216E and L236S, which were detected with premature pubarche or hyperandrogenic adolescent girls suspected to be affected from nonclassical 3betaHSD deficiency, coupled with the previous studies reporting that no mutations were found in both HSD3B1 and/or HSD3B2 genes in such patients strongly support the conclusion that this disorder does not result from a mutant 3betaHSD isoenzyme. The present study provides biochemical evidence supporting the involvement of a new molecular mechanism in classical 3betaHSD deficiency involving protein instability and further illustrates the complexity of the genotype-phenotype relationships of this disease, in addition to providing further valuable information concerning the structure-function relationships of the 3betaHSD superfamily.

Mutations in the MDR3 gene cause progressive familial intrahepatic cholestasis.

Class III multidrug resistance (MDR) P-glycoproteins (P-gp), mdr2 in mice and MDR3 in man, mediate the translocation of phosphatidylcholine across the canalicular membrane of the hepatocyte. Mice with a disrupted mdr2 gene completely lack biliary phospholipid excretion and develop progressive liver disease, characterized histologically by portal inflammation, proliferation of the bile duct epithelium, and fibrosis. This disease phenotype is very similar to a subtype of progressive familial intrahepatic cholestasis, hallmarked by a high serum gamma-glutamyltransferase (gamma-GT) activity. We report immunohistochemistry for MDR3 P-gp, reverse transcription-coupled PCR sequence analysis, and genomic DNA analysis of MDR3 from two progressive familial intrahepatic cholestasis patients with high serum gamma-GT. Canalicular staining for MDR3 P-gp was negative in liver tissue of both patients. Reverse transcription-coupled PCR sequencing of the first patient's sequence demonstrated a homozygous 7-bp deletion, starting at codon 132, which results in a frameshift and introduces a stop codon 29 codons downstream. The second patient is homozygous for a nonsense mutation in codon 957 (C --> T) that introduces a stop codon (TGA). Our results demonstrate that mutations in the human MDR3 gene lead to progressive familial intrahepatic cholestasis with high serum gamma-GT. The histopathological picture in these patients is very similar to that in the corresponding mdr2(-/-) mouse, in which mdr2 P-gp deficiency induces complete absence of phospholipid in bile.

Survey of functional assessment procedures used with individuals who display mental retardation and severe problem behaviors.

A survey was conducted to catalog the assessments used by practitioners to evaluate the problem behaviors displayed by clients with mental retardation. Questionnaires were mailed to 300 members of the Psychology Division of the American Association on Mental Retardation. Most practitioners rated functional assessment procedures as extremely or very useful. Indirect and descriptive assessments were considered more useful than experimental manipulation. Findings were discussed with emphasis on the difficulties in conducting functional assessments. These results may be useful for practitioners who are designing behavior training programs and directing further research to improve functional assessment strategies.

Expression of the liver Na+-independent organic anion transporting polypeptide (oatp-1) in rats with bile duct ligation.

BACKGROUND/AIMS: In rats with cholestasis due to bile duct ligation, the expression of the Na+-dependent taurocholate co-transporting polypeptide, the major uptake system for conjugated bile acids in hepatocytes, is down-regulated. Our purpose was to examine the expression of the organic anion transporting polypeptide, a Na+-independent uptake system for bile acids and organic anions, in rats with bile duct ligation, and to compare the expression of organic anion transporting polypeptide to that of Na+-dependent taurocholate co-transporting polypeptide. METHODS: Rats with bile duct ligation were studied after 1, 3 or 7 days. The expression of organic anion transporting polypeptide and Na+-dependent taurocholate co-transporting polypeptide proteins was examined by Western blot analysis and steady-state mRNA levels were determined by Northern blot analysis using cDNAs encoding organic anion transporting polypeptide and Na+-dependent taurocholate co-transporting polypeptide. Sham-operated animals were used as controls. RESULTS: The expression of organic anion transporting polypeptide protein was slightly, but not significantly, decreased 1 day after ligation (10.3%); it was markedly decreased after 3 days (56.9%; p<0.03) and 7 days (46.8%; p<0.05) compared to sham-operated animals. Steady-state mRNA levels of organic anion transporting polypeptide were decreased by 79.7% (p<0.04), 48.8% (p<0.02) and 57.4% (p<0.02) after 1, 3 and 7 days respectively. For comparison, Na+-dependent taurocholate co-transporting polypeptide protein and mRNA levels were decreased by 73.8% (p<0.03) and 70.0% (p<0.05) at 1 day and remained low after 3 and 7 days. CONCLUSIONS: In rats with bile duct ligation, the expression of organic anion transporting polypeptide protein and mRNA is down-regulated. Down-regulation of organic anion transporting polypeptide seems less pronounced than that of Na+-dependent taurocholate co-transporting polypeptide. Nevertheless, it could contribute to a decreased uptake of potentially toxic bile acids or organic anions in this situation.

Ontogenic expression of the Na(+)-independent organic anion transporting polypeptide (oatp) in rat liver and kidney.

BACKGROUND/AIMS: A cDNA (2.7 kb) encoding a rat liver basolateral Na(+)-independent organic anion transporter (oatp) has recently been cloned. The aim of the present study was to clarify the mechanisms of bile formation during development. METHODS: The ontogenic expression of oatp was examined by northern blot analysis and in situ hybridization in rat liver. The expression of oatp in the kidney was also studied in parallel. RESULTS: In the liver, a 2.5 kb oatp mRNA was first detected in the fetus on day 16 of gestation. The amount of this oatp mRNA remained stable during the perinatal period and increased dramatically after weaning. Other transcripts probably corresponding to oatp-related mRNAs also display a late expression pattern in the perinatal period. In contrast, Na+/taurocholate transporting polypeptide (Ntcp) mRNA was first detected on day 20 of gestation. By in situ hybridization, oatp mRNA was localized into hepatocytes and distributed without lobular heterogeneity. In the kidney, a single 2.4 kb oatp transcript was detected from birth to adult age. This transcript was exclusively distributed in the epithelial cells of the proximal tubules localized in the kidney cortex and the outer medulla. CONCLUSIONS: These results indicate that oatp undergoes a time-related expression in rat liver and kidney during development and that its gene transcription precedes Ntcp gene transcription in the liver. The delayed expression of oatp at the perinatal period may explain in part the immaturity of bile formation and the physiological neonatal cholestasis.

New proteins in the rat CYP2B subfamily: presence in liver microsomes of the constitutive CYP2B3 protein and the phenobarbital-inducible protein product of alternatively spliced CYP2B2 mRNA.

The rat CYP2B gene subfamily includes CYP2B1, CYP2B2 and CYP2B3. Translation of an alternatively spliced hepatic CYP2B2 mRNA would generate a CYP2B2 variant, CYP2B2v, having eight additional amino acid residues inserted between CYP2B2 positions 274 and 275. The presence of CYP2B3 and CYP2B2v in rat liver has yet to be demonstrated. cDNA expression vectors were obtained for CYP2B1, CYP2B2, CYP2B3 and CYP2B2v. All four proteins react with an anti-CYP2B1 antibody and can be resolved by SDS-PAGE. A CYP2B3-specific polyclonal antibody raised against an undecapeptide (SPVDPNTIDMT) from near the C-terminus of CYP2B3 detected a constitutive protein on immunoblots of rat liver microsomes, thus demonstrating that the CYP2B3 mRNA is translated in the liver. Similarly, a CYP2B2v-specific polyclonal antibody was raised against a peptide containing the eight additional amino acid residues (VSPAWMRE) predicted to be present in the CYP2B2v protein. It detected a phenobarbital- and Aroclor 1254-inducible protein in rat liver microsomes. Microsomes of Ad293 cells expressing cDNAs for CYP2B2 and CYP2B2v were used to metabolize 7,12-dimethylbenz[a]anthracene (DMBA), and the metabolites produced were compared with those generated by microsomes of cells expressing CYP2B1 cDNA. CYP2B2v had activity similar to that of CYP2B2 for DMBA metabolism. Both CYP2B2 forms preferentially catalyzed 12-hydroxylation, whereas CYP2B1 preferred 7-hydroxylation and exhibited turnover that was strongly suppressed as previously reported. These results demonstrate the existence in rat liver of two new CYP2B proteins: CYP2B3, the major constitutive CYP2B form, and CYP2B2v, which represents a rare case of non-aberrant alternative splicing among xenobiotic-metabolizing P450s.

Rat liver cytochrome P450 2B3: structure of the CYP2B3 gene and immunological identification of a constitutive P450 2B3-like protein in rat liver.

The cytochrome P450 2B subfamily in the rat contains an estimated eight to eleven members at the genomic level. Synthesis in the liver of the prototypic forms P450 2B1 and P450 2B2 is dramatically induced by phenobarbital. The 1.9-kb mRNA for P450 2B3, a third member of the P450 2B subfamily, is constitutively present in rat liver but is not inducible by phenobarbital. We have now cloned and sequenced exonic sequences corresponding to the entire 2B3 mRNA and determined their exon-intron structure, which is identical to that of CYP2B1/CYP2B2 and other CYP2B genes. A putative CYP2B3 transcription start site was identified and CYP2B3 5'- and 3'-flanking sequences were compared to those of CYP2B1 and CYP2B2. CYP2B3, like CYP2B1 and CYP2B2, has a modified TATA box preceding the transcription start site and lacks the canonical polyadenylation signal preceding the poly(A) site. A 2B3 expression vector, pMT2-2B3, directed the synthesis in COS-1 cells of an approximately 50-kD protein detectable on Western blots with a polyclonal antibody and with one of four monoclonal antibodies raised against 2B1 but not with a polyclonal antibody raised against P450 PB6. The 2B3 protein migrated with a slightly higher electrophoretic mobility than 2B1 and comigrated with a protein detected by anti-2B1 antibodies in liver microsomes from untreated rats. The results indicate that a 2B3-like protein is present in rat liver and that it is distinct from P450 PB6 and other known constitutive rat hepatic P450s.

A long-term follow-up study of asymptomatic hepatitis B surface antigen-positive carriers in Montreal.

BACKGROUND/AIMS: Prospective studies from the Far East and Alaska have shown an increased mortality from cirrhosis and/or hepatocellular carcinoma in asymptomatic hepatitis B virus (HBV) carriers. The magnitude of this risk in apparently healthy North American carriers remains undefined. METHODS: The outcomes of 317 asymptomatic hepatitis B surface antigen-positive carriers from the Montreal area were examined after 16 years of follow-up. A majority of carriers were of French Canadian origin, were positive for antibody to hepatitis B e antigen, and had normal serum transaminase levels; institutionalization in orphanages as infants or children was the most important epidemiological risk factor, suggesting horizontal transmission of HBV during childhood. RESULTS: At follow-up, mean age was 46 +/- 8 years; 3 carriers had died of HBV-related cirrhosis, 1 of alcoholic cirrhosis, and 9 of causes unrelated to liver disease. No carrier died of hepatocellular carcinoma; had the risk of hepatocellular carcinoma been similar to that reported from the Far East and Alaska, 17 cases of hepatocellular carcinoma-related deaths would have been expected. During follow-up, the annual negativation rate for hepatitis B surface antigen was 0.7%. CONCLUSIONS: In asymptomatic HBV carriers from Montreal, a majority are "healthy" carriers and remain asymptomatic after 16 years of follow-up and the risk of death from HBV-related cirrhosis and/or hepatocellular carcinoma is low.

Metabolism of 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK) in human kidney epithelial cells transfected with rat CYP2B1 cDNA.

In all species where it has been tested, the tobacco-specific nitrosamine 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK) has been shown to be a potent carcinogen, and NNK and other nitrosamines may play a role in human tobacco-related carcinogenesis. Purified rat CYP2B1 has been shown to metabolize NNK, and the CYP2B1 gene is expressed constitutively in rat lung. The objectives of this study were to test the capacity of CYP2B1, synthesized from a rat hepatic cDNA in Ad293 cells, to metabolize NNK, and to define the type and the proportions of the final metabolites produced. Ad293 cells were transfected with a CYP2B1 expression vector (pMT2-2B1), or with a control vector and incubated in culture medium containing [3H]NNK, after which alpha-carbon hydroxylation and pyridine N-oxidation metabolites were identified by HPLC analysis and quantitated by scintillation counting. pMT2-2B1-transfected cells were capable of catalyzing alpha-carbon hydroxylation and pyridine N-oxidation of NNK, although the reduction product 4-(methylnitrosamino)-1-(3-pyridyl)-1-butan-1-ol(NNAL) was the major metabolite formed in cells regardless of transfection treatment. The total amount of alpha-carbon hydroxylation metabolites produced by pMT2-2B1-transfected cells was greater than that of pyridine N-oxidation metabolites. However, pMT2-2B1 transfected cells produced approximately ten-fold more pyridine N-oxidation metabolites and only two-fold more alpha-carbon hydroxylation metabolites than control cells. Furthermore, the amount of NNAL-N-oxide was much lower than that of NNK-N-oxide in the medium of pMT2-2B1-transfected cells, even though the amount of available NNAL, resulting from carbonyl reduction of NNK, was very high; this suggests that NNAL is poorly N-oxidized by CYP2B1 compared to NNK. These results show that within living cells NNK was metabolized by CYP2B1 via both the pyridine N-oxidation and alpha-carbon hydroxylation pathways. However, CYP2B1 preferentially catalyzed pyridine N-oxidation, which is considered to be a deactivation reaction.

The relationship between functional assessment and treatment selection for aggressive behaviors.

Functional assessment seeks to elucidate the variables controlling a maladaptive behavior. Based on such an assessment, effective treatments can be designed that focus on replacing that maladaptive behavior with a functionally equivalent adaptive prosocial behavior. This technique has been promoted as an effective means of improving treatments by increasing the focus on skill development and reducing the use of aversive and restrictive procedures. The literature for the behavioral treatment of aggression for persons with mental retardation or developmental delays was examined from 1979 through 1990. During that period the use of functional assessment and skill training increased; however, the increased use of functional assessment did not result in the reduced use of intrusive procedures. Potential reasons for these results are discussed, and a call for an increased emphasis on functional assessment methodology is made.

Screening for trisomy 21 with ultrasonographic determination of biparietal diameter/femur length ratio.

Ultrasonographic determination of biparietal diameter/femur length ratios performed at 16 or 17 weeks' gestation in fetuses with trisomy 21 were not statistically different from those of 155 normal fetuses. It appears that this test could not be used for screening for trisomy 21.

Alternative splicing of mRNA encoding rat liver cytochrome P450e (P450IIB2).

Cytochrome P450e (P450IIB2) is a phenobarbital(PB)-inducible member of the rat liver P450IIB subfamily. Among P450 cDNA clones previously isolated from a cDNA library made from the liver of a single rat were several that contained P450e inserts, including PB13, PB16, and PB22. By nucleotide sequence analysis, the PB16 and PB22 inserts have now been found to contain an additional 24-bp segment not present in the PB13 insert or in previously reported P450e-coding sequences. According to the published P450e genomic sequence, the 24-bp segment is exactly at the junction of the fifth and the sixth exons and its sequence is identical to the first 24 bp of the fifth intron. Translation of this segment would add 8 amino acid residues to the P450e protein. To detect the alternatively spliced P450e mRNA, a synthetic oligodeoxyribonucleotide (oligo) corresponding to 18 of the 24 bp of the intronic sequence found in the PB16 and PB22 inserts was made. This oligo hybridized with a 2.1-kb RNA on Northern blots of liver RNA from PB- or Aroclor 1254-treated rats. Taken together, these results indicate that individual rats can possess both forms of P450e mRNA and that an alternative splicing mechanism is responsible for their formation.

A full-symmetry translation function based on electron density.

A method for positioning an oriented fragment within the unit cell is presented. It is based on a correlation between a model and observed data which is performed in Fourier rather than Patterson space. Symmetry-related molecules are located in the electron density map calculated in space group P1, with the phases derived from a model that is correctly oriented but arbitrarily positioned in the unit cell. It is shown that considering all symmetry elements simultaneously substantially increases the sensitivity of the method and makes it less susceptible to the errors in the model. The procedure also automatically incorporates a penalty for the overlap of symmetry-related molecules, and the stringency of this requirement is easily modified. The method has been tested on two different proteins and the results compare favorably with other translation functions.

Fermentation kinetics of spent sulfite liquor by Saccharomyces cerevisiae.

The growth kinetics of the yeast Saccharomyces cerevisiae and the production rate of ethanol have been studied in batch fermentation under anaerobic conditions in a 20-L fermentor. Two substrates were used in fermentation trials: a synthetic mixture of three fermentable sugars, D-glucose, D-mannose, and D-galactose, and a low-yield liquor originating from a bisulfite cooking process. The Monod model adequately described the system in relation to the specific growth rate micro(x) and the specific product formation rate micro(P). Different fermentation parameters (growth rate, substrate utilization, and product formation) were determined for the synthetic mixture and the bisulfite liquor. It was observed that the specific growth rate is much lower in spent sulfite liquor than in a synthetic medium. However, the specific product formation rate remains the same in both media.

Extracellular proteins secreted by the basidiomycete Schizophyllum commune in response to carbon source.

The secretion of 1,4-beta-D-glucanases by the basidiomycete Schizophyllum commune in response to cellulose or cellobiose has been studied. The proteins were labeled with 35S, and the secretion of enzymes was measured by beta-glucosidase and carboxymethyl cellulase activities and by immunoprecipitation with specific antibodies. The antigen proteins used were a beta-glucosidase (Mr, 93,000), an avicelase (avicelase II; Mr, 64,000), and a carboxymethyl cellulose (carboxymethyl cellulase I; Mr 41,000). The beta-glucosidase was initially secreted as an Mr 110,000 form, which was followed later by lower-molecular-weight (88,000 to 93,000) forms. The avicelase II, which accounted for about 50% of the secreted labeled protein, had an Mr of 64,000. Secretion of the related avicelase I (Mr 61,000) followed later. The carboxymethyl cellulose I was secreted in two molecular weight forms, Mr 44,000 and 41,000. The evidence is consistent with the idea that three genes account for the secreted glucanase activities. Other species result from different glycosylation or proteolytic cleavage processing, which may occur during or after secretion. The beta-glucosidase secretion appears to be regulated differently than that of avicelase II or carboxymethyl cellulase I; the latter two were regulated coordinately under the conditions used in this work. No common immune determinants between the three antigens were observed.

Molecular cloning of a Bacillus subtilis xylanase gene in Escherichia coli.

A gene coding for xylanase synthesis in Bacillus subtilis was isolated by direct shotgun cloning using Escherichia coli as a host. Following partial digestion of B. subtilis chromosomal DNA with PstI or EcoRI restriction enzymes, fragments ranging from 3 to 7 kb were introduced into the PstI or EcoRI sites of pBR325. Transformed colonies having lost either the ampicillin or chloramphenicol resistance markers were screened directly on 1% xylan plates. Out of 8000 transformants, ten xylanase-positive clones were identified by the clearing zone around lysozyme-treated colonies. Further characterization of one of the clones showed that the xylanase gene was present in a 3.9-kb insert within the PstI site of the plasmid pBR325. Retransformation of E. coli strain with the xylanase-positive hybrid plasmid pRH271 showed 100% transformation to xylanase production. The intracellular xylanase produced by the transformed E. coli was purified by ion exchange and gel permeation chromatography. The electrophoretic mobility of the purified xylanase indicated an Mr of 22 000.

Isolation and Characterization of a Xylanase from Bacillus subtilis.

Partial characterization of an extracellular xylanase isolated by chromatography from Bacillus subtilis gave a molecular weight of 32,000 and optimum pH and temperature of 5.0 and 50 degrees C, respectively. K(m) and V(max) values, determined with a soluble larchwood xylan, were 0.16% and 7.0 x 10 mumol min mg of enzyme respectively. The amino acid composition showed more basic amino acid residues than in a previously characterized xylanase from a white-rot fungus.