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Biomedical subjects

M Held

Publications and source records attributed to M Held.

At least 19 recordsLinked to original sources
PubMed2006

Circumventing the effect of product toxicity: development of a novel two-stage production process for the lantibiotic gallidermin.

Lantibiotics such as gallidermin are lanthionine-containing polypeptide antibiotics produced by gram-positive bacteria that might become relevant for the treatment of various infectious diseases. So far, self-toxicity has prevented the isolation of efficient overproducing strains, thus hampering their thorough investigation and preventing their exploitation in fields other than the food area. We wanted to investigate the effect of lantibiotic precursor peptides on the producing strains in order to evaluate novel strategies for the overproduction of these promising peptides. In this study, gallidermin was chosen as a representative example of the type A lantibiotics. A Staphylococcus gallinarum Tü3928 mutant, whose gene for the extracellular pregallidermin protease GdmP was replaced by a kanamycin-resistance gene, was constructed. Mass spectrometry (MS) analysis indicated that this mutant produced fully posttranslationally modified gallidermin precursors with truncated versions of the leader peptide, but not the entire leader as predicted from the gdmA sequence. In filter-on-plate assays, these truncated pregallidermins showed no toxicity against Staphylococcus gallinarum Tü3928 up to a concentration of 8 g/liter (corresponding to approximately 2.35 mM), while gallidermin produced clear inhibitory zones at concentrations as low as 0.25 g/liter (0.12 mM). We showed that the lack of toxicity is due entirely to the presence of the truncated leader, since MS as well as bioassay analysis showed that the peptides resulting from tryptic cleavage of pregallidermins and gallidermin produced by S. gallinarum Tü3928 had identical masses and approximately the same specific activity. This demonstrates that even a shortened leader sequence is sufficient to prevent the toxicity of mature gallidermin. In nonoptimized fermentations, the gdmP mutant produced pregallidermin to a 50%-higher molar titer, suggesting that the absence of self-toxicity has a beneficial effect on gallidermin production and giving a first confirmation of the suitability of the overproduction strategy.

Amino Acid Sequence↗
PubMed2006

[Z-plasty for valgus deformity in total knee arthroplasty].

PURPOSE OF THE STUDY: Several options for treatment of valgus deformity in total knee arthroplasty (TKA) have been described. In 2002 the lateral approach to the valgus knee with Z-plasty of the articular capsule involving part of Hoffa's fat pad started to be used in our department. In this study the surgical technique, including steps for gradual deformity correction, is described and shortterm results are evaluated. MATERIAL: A total of 1136 TKAs were carried out in the period from 1994 to 2004; of these 131 (11 %) were performed on valgus knee. After a visit to the Schulthess Klinik and personal communication with Dr. med. T. Drobny, we began to use the lateral approach to the valgus knee, with Z-plasty of the articular capsule and involvement of Hoffa's fat pad. Forty-two patients (35 women and 7 men) were treated by this technique. The average age of this group was 71 years, and the average preoperative valgus deformity was 20.5 degrees. METHODS SURGICAL TECHNIQUE: A skin incision is made along the midline and, in its lower part, it is led toward the lateral border of the tibial tubercle. The joint capsule is incised in the superficial layer at about 2 cm lateral to the patella. Dissection of the superficial and deep layers of the capsule is made laterally, extending up to 4 cm. After joint exposure, the fat pad is separated from the medial attachment and preserved, on a lateral pedicle, with the patellar ligament. If needed, this flap can be used to close a defect in the distal articular capsule. By including both parts of the joint capsule produced by Z-plasty, medial transposition of the patella is achieved after suture. The deformity is corrected in a sequential manner according to its severity and the effect of release in each step, as follows: 1) Point incisions of the iliotibial band at a 5-cm distance above the articular fissure (piecrusting). 2) Subperiosteal elevation of the iliotibial band attachment from Gerdy's tubercle. 3) Release of the posterolateral capsule. 4) Subperiosteal release of the femoral attachment of the lateral collaterall ligament and dissection of the popliteal muscle. 5) Release of the lateral head of the gastrocnemius muscle. The evaluation of patients was based on the Knee Society Clinical Rating System. RESULTS: Using this surgical technique, correction of deformity was achieved in all patients. The knee axis after surgery improved to 6.6 degrees on the average. The more extensive dissection of lateral structures resulted in larger blood losses, which were on average 1150 ml, and the procedure also required a longer tourniquet application (55 min). The patients were followed up on average for 22 months. The Knee Score assessment in the whole group (42 knees) was on average 90.6 points, with 92.0, 93.3 and 87.9 for rating system categories A, B and C, respectively. The average range of motion was 0 to 118 degrees , and none of the patients reported femoropatellar problems. Revision surgery for hematoma was performed in one patient and puncture of the knee joint had to be done in several patients. Redress for postoperative motion restriction was carried out in three patients and one patient underwent repeat surgery for infection. DISCUSSION: The lateral approach with Z-plasty of the capsule and fat pad involvement provides maximal release of and access to the lateral structures, reduces the risk of insufficient blood supply of the patella and also resolves patellar subluxation. This technique thus allows us to reduce the probability of developing femoropatellar problems that are frequently responsible for poor TKA outcomes in the valgus knee. CONCLUSIONS: The technique described here is an effective approach to the valgus knee requiring total replacement. It provides good access to exposed lateral structures and, with the use of Z-plasty, permits correct alignment and tracking of the patella. In addition, it minimally interferes with blood supply to the patella and completely avoids problems associated with suture of the articular capsule.

Aged↗
PubMed2004

Comparative investigation of the biocompatibility of various silicon nitride ceramic qualities in vitro.

There is a controversy about the biocompatibility of silicon nitride ceramics contained in the literature, which appears to be related to a factor of the individual chemical composition of different qualities of silicon nitride ceramics and of the different surface properties. This study attempts to investigate the cytotoxicity of different qualities of industrial silicon nitride ceramics applying an L929-cell culture model in a direct contact assay combined with a cell viability assessment. Five different qualities of industrial standard silicon nitride ceramics were chosen for in vitro testing. The chemical composition was determined by EDS analysis. Different biomedically approved aluminium oxide qualities, a titanium alloy, glass and polyvinylchloride (PVC) served as control materials. L929 mice fibroblasts were incubated directly on the materials for 24 h, stained with bisbenzimide and propidium iodine for double fluorochromasia viability testing, and evaluated by inversion-fluorescence microscopy to control cell morphology, viability and cell counts compared to empty well values. Scanning electron microscopy was applied to additionally investigate cell morphology. There was no observation of cytotoxic effects on the silicon nitride ceramic samples; moreover cell morphology remained the same as on aluminium oxide and titanium. Viability testing revealed the presence of avital cells exclusively on PVC, which served as a negative control. Cell counts on all polished surfaces showed significantly higher numbers, whereas some rough surface samples showed significantly lower numbers. We conclude that silicon nitride ceramics show no cytotoxic effects and should be considered for biomedical application owing to its favourable physiochemical properties, especially its superior resistance to mechanical stress, which would be useful for compression loaded conditions. Polished surfaces would appear to promote advanced biocompatibility.

Aluminum Oxide↗
PubMed2004

[Total knee arthroplasty with the Beznoska S.V.L. implant: short-term results].

PURPOSE OF THE STUDY: To present and evaluate short-term clinical results of total knee arthroplasty using the Beznoska S. V. L. implant and to compare them with the results of other authors. MATERIAL: In the period from April 1997 to October 2002, 197 total knee replacements with a S. V. L. implant were carried out of these, 164 implants were evaluated in 146 patients. This group comprised 116 women (78 %) and 48 men (22 %), with an average age of 73.6 years (range, 63 to 83) at the time of surgery. The patients were evaluated on average at 4.3 years (range, 1.5 to 6.5) after surgery. Indications for replacement were primary knee arthritis in 151, rheumatoid arthritis in nine, secondary post-traumatic arthritis in two and conditions following tibial osteotomy in two cases. METHODS: The results were evaluated using the Knee Society Clinical Rating System which consists of three parts: Knee Score (100 points), Knee Function Score (100 points) and Categorical Score (allocating patients to three groups according to function deficiencies of other joints). X-ray images were examined for implant position, the presence of radiolucent lines and patellar position, and assessed on the basis of the Knee Society Total Knee Arthroplasty Roentgenographic and Scoring System. RESULTS: No or mild pain in the treated joint was reported by 90.2 % of the patients. Severe pain was not recorded at all. The average maximal range of flexion increased from 94 degrees preoperatively to 104 degrees post-operatively. The range of motion more than 90 degrees and that of more than 100 degrees were recorded in 96 % and 76.8 % of the operated-on knees, respectively. An anteroposterior mild instability of 5 to 10 mm was objectively found in nine knees (5.5 %) a medial laxity of 6 to 9 degrees was detected in 36 knees (22 %) and that of 10 to 15 degrees only in one patient. Severe instability was not recorded. The leg axis achieved after surgery was on average 6.4 degrees valgus, compared to 5.5 degrees varus before surgery. The total Knee Score was 85.1 points (range, 53 to 100), with excellent or good outcomes in 151 knee replacements (92 %). Six patients (4.6 %) reported failure to walk a distance of more than 500 m on an even terrain, six (4.6 %) could not manage the stairs and five (3 %) required a permanent use of two crutches or a walking frame. The average function score, which also included the effect of concomitant diseases of other joints, was 64.9 points (range, 40 to 100), with excellent or very good outcomes being achieved in 64 implants (39 %). On X-ray examination of implant position in anteroposterior projection, the average valgus angle of the femoral component was 94.8 degrees (range, 92 to 100) and the tibial angle was 90.3 degrees (range, 85 to 94). In lateral projection the flexion angle of the femoral component was 2.5 degrees (-1 to 6) and the average dorsal tilt of the tibia was 3 degrees. Distinct radiolucent lines up to 1 mm in width were seen in the femoral component in 10 (6 %) cases and in the tibial component in 27 (16.5 %) cases, this occurred in zones 1, 2 or 4. Wider lines of 2 mm were present in both components in 6 (3 %) cases. Radiolucent lines were recorded in 43 (26 %) implants. The patella examined in axial projection was correctly centered in 140 (85 %) total knee replacements. Eleven patients reported femoropatellar problems and, in three of them, patella replacement was subsequently performed. No aseptic loosening occurred and one deep infection (0.6 %) was treated by a two-stage reimplantation. DISCUSSION: Excellent to very good outcomes, with an average Knee Score of 85.1 points, were achieved in 92 % of the implants. The total outcome characterized by an average Functional Score of 64.9 points was related to a higher average age of our patients and a high proportion of patients with diseases of other joints, which interfered with overall mobility and self-sufficiency. The results of implant position evaluation, based on X-ray examination, showed good values, which testifies to the use of an appropriate surgical technique and accuracy of the instrumentation applied. The occurrence of radiolucent lines was low, as was the number of complications. Our results are comparable with those reported in the literature. CONCLUSIONS: Our short-term evaluation shows that the S. V. L. implant is fully useful for total knee replacement in patients of higher age categories.

Aged↗
PubMed2002

Influence of mutation type and location on phenotype in 123 patients with Rett syndrome.

Rett syndrome (RTT) is a neurodevelopmental disorder that almost exclusively affects girls. It is caused by mutations in the MECP2 gene that encodes the methyl-CpG-binding protein 2 (MeCP2). In this study we correlated mutation type and location with the severity of the phenotype in 123 girls with RTT. The ability to sit, walk, speak, hand function, head growth, occurrence of epilepsy and a combined severity score were assessed in all girls at 5 years of age and then statistically correlated with the results of the molecular genetic tests. We found that patients who carry either missense mutations or deletions located within the hotspot for deletions, an area between the base pairs (bp) 1030 and 1207 of the MECP2 gene, present with a milder phenotype than other patients. We correlated the location of the mutations with the phenotype and found that all mutations that lead to either a complete or partial truncation of the region coding for the nuclear localisation signal (NLS) are associated with a more severe phenotype than other truncating mutations (p = 0.001). We did not find a significant difference between the patients with mutations in the methyl-CpG-binding domain (MBD) and those with mutations in the transcriptional repression domain (TRD). We conclude that mutation type and location correlate with the phenotype in Rett syndrome. All mutations that impair the nuclear localisation signal (NLS) are associated with more severe phenotypes.

Binding Sites↗
PubMed2001

Gastric cancer and human leukocyte antigen: distinct DQ and DR alleles are associated with development of gastric cancer and infection by Helicobacter pylori.

DNA and sera from 130 cases of gastric cancer and 263 population-based controls were analyzed to study the association of HLA class II DR-DQ alleles with Helicobacter pylori (Hp) infection and the risk for gastric cancer. Presence of the DQA1*0102 allele was inversely and significantly associated with Hp seropositivity (P = 2 x 10(-5)), which is an independent replication of previous findings. However, this inverse relationship with Hp did not correspond with a reduced risk of gastric cancer. At the DRB1 locus, the *1601 allele was significantly associated with an increased gastric cancer risk with an odds ratio (95% confidence interval) of 8.7 (range, 2.7-28.0). The effect of *1601 was more pronounced among Hp-negative subjects, and the association was stronger with the diffuse, rather than with the intestinal, histological type of gastric cancer. Because none of the HLA alleles were associated with both Hp infection and gastric cancer, the HLA DR-DQ alleles are linked with gastric cancer risk through other mechanisms than an increased susceptibility to Hp infection.

Adenocarcinoma↗
PubMed2001

Helicobacter pylori in gastric cancer established by CagA immunoblot as a marker of past infection.

BACKGROUND & AIMS: Helicobacter pylori may disappear spontaneously with progressing precancerous changes and invalidate serologic studies of its association with gastric cancer. We reestimated the strength of the H. pylori-gastric cancer relationship, using both conventional immunoglobulin (Ig) G enzyme-linked immunosorbent assay (ELISA) and immunoblot (against cytotoxin-associated antigen A [CagA] antibodies that prevail longer after eradication) to detect past H. pylori exposure more relevant for time at cancer initiation. METHODS: In our population-based case-control study, the seroprevalence among 298 gastric adenocarcinoma cases was 72% (IgG ELISA) and 91% (immunoblot) vs. 55% and 56% among 244 controls frequency-matched for age and gender. RESULTS: Using IgG ELISA only, the adjusted OR for noncardia gastric cancer among H. pylori-positive subjects was 2.2 (95% confidence interval [CI], 1.4-3.6). When ELISA-/CagA+ subjects (odds ratio [OR], 68.0) were removed from the reference, the OR rose to 21.0 (95% CI, 8.3-53.4) and the previous effect modification by age disappeared. ELISA+/CagA- subjects had an OR of 5.0 (95% CI, 1.1-23.6). There were no associations with cardia cancer. CONCLUSIONS: The weaker H. pylori-cancer relationships in studies based on IgG ELISA rather than CagA may be caused by misclassification of relevant exposure. A much stronger relationship emerges with more accurate exposure classification. In the general Swedish population, 71% of noncardia adenocarcinomas were attributable to H. pylori.

Adenocarcinoma↗
PubMed2001

[Cochlear hearing loss following Mycoplasma pneumoniae infection].

BACKGROUND: A sudden unilateral hearing loss in childhood is commonly regarded as an unusual event. CASE-REPORT: In this paper, we report of a 10 year old girl suffering from a unilateral right-sided sudden hearing loss following an acute infection with Mycoplasma pneumoniae, which is also rarely observed. Maximum hearing loss was estimated around 30 dB (0.25-6 kHz), which resolved after infusions using plasma expanders. Both transitory and distortion product otoacoustic emissions remained absent, while latencies of acoustically evoked potentials were normal. DISCUSSION: This suggests a damage of outer hair cell function as an explanation for the observed hearing loss. The coincidence of two rare events for children such as a spontaneous sudden unilateral hearing loss combined with an infection with Mycoplasma pneumoniae gives rise to the hypothesis of a causal relationship that is discussed according to the literature.

Acute Disease↗
PubMed2001

Does metal coating improve the durability of silicone voice prostheses?

Voice prostheses, which are used for voice rehabilitation in cancer patients after laryngectomy, usually become colonized with a mixed biofilm of bacteria and Candida after 2-4 months and lose their efficiency. It is essential to ensure the stability and biocompatibility of these implants. With the aid of surface frame analysis we have shown that local antifungal treatment is inadequate for eliminating the deep infiltration and encapsulation of Candida colonies in silicone. A surface that prevents the adhesion of microorganisms is required. Because of its special properties there are few methods available for coating silicone. We employed, for the first time, a new method of surface modification using anodic vacuum arc coating. Using this method it was possible to obtain a solid film of gold or titanium metal with a layer thickness < 100 nm. Resistance against Candida colonization and destruction of coated prostheses were tested both in vitro and in vivo. A titanium coating seemed to provide the optimal solution to the problem, because surface adhesion and the smoothness of the material appeared to be superior to those of a gold coating.

Biocompatible Materials↗
PubMed2000

[Inflammatory pseudotumor of the nasal septum].

An inflammatory pseudotumor occurs unifocally and is a benign tumor that was initially described in the lung. In the present case report a 24-year-old woman experienced progressive nasal obstruction because of an abnormality of the nasal septum. A cauliflower-like tumor of the anterior region of the septum cartilage was seen macroscopically and was completely resected. This was diagnosed histologically as an inflammatory pseudotumor. The literature is reviewed and differential diagnoses discussed. Various therapeutic procedures are noted, but the treatment of choice is complete resection of tumor.

Adult↗
PubMed1999

An integrated process for the production of toxic catechols from toxic phenols based on a designer biocatalyst.

We describe the biocatalytic production of 3-phenylcatechol from 2-phenylphenol with the whole cell biocatalyst Escherichia coli JM101 (pHBP461). The recombinant produces 2-hydroxybiphenyl 3-monooxygenase, an enzyme from Pseudomonas azelaica HBP1. This enzyme introduces a hydroxyl-group at the C3-position of a variety of 2-substituted phenols, such as 2-phenylphenol. This permits the biocatalytic production of 3-substituted catechols, which are difficult to synthesize chemically. Both 2-phenylphenol and 3-phenylcatechol are highly toxic to E. coli. The toxic effects of 2-phenylphenol were minimized by feeding this substrate to the reactor at a rate slightly below the maximum biooxidation rate. As a result, the substrate concentration in the reactor remained below toxic levels during the bioconversion. The toxic product formed was removed by continuous adsorption on the solid resin Amberlite XAD-4. To this end the reaction mixture, containing the biocatalyst, was pumped continuously through an external loop with a fluidized bed of the resin. This resin efficiently and quantitatively adsorbed both 3-phenylcatechol and the remaining trace amounts of 2-phenylphenol. Consequently, the concentrations of these compounds were kept at subtoxic levels (below 100 mg L-1) and gram amounts of 3-phenylcatechol were produced with space-time yields of up to 0.39 g L-1 h-1. The product was recovered from the resin by acidic methanol elution and purified by recrystallization from n-hexane resulting in overall yields exceeding 59%. The optimized system served as a surprisingly simple and efficient integrated process, that allows the bioconversion of toxic substrates to toxic products with whole cell biocatalysts.

Adsorption↗
PubMed1999

Treatment of chronic sarcoidosis with an azathioprine/prednisolone regimen.

In a few patients with chronic sarcoidosis, prolonged, unacceptably high doses of corticosteroids are required to achieve symptomatic relief. In these cases, a corticosteroid-sparing drug might be administered to allow long-term treatment without the adverse effects of corticosteroids. This study examines azathioprine as a prednisolone-sparing treatment. In an open study, the course of 11 patients with chronic sarcoidosis was analysed. In an induction phase, 2 mg azathioprine x kg body weight (BW)(-1) x day(-1) in combination with 0.6-0.8 mg prednisolone x kg BW(-1) x day(-1) were administered with prednisolone being reduced to 0.1 mg x kg BW(-1) x day(-1) within 2-3 months. This was followed by a 21-22-month maintenance phase with 2 mg azathioprine x kg BW(-1) x day(-1) and 0.1 mg prednisolone x kg BW(-1) day(-1). Clinical parameters and immunological findings of bronchoalveolar lavage (BAL) were analysed. All patients had significant symptomatic relief and improvements or resolutions of physiological, serological and radiographic findings without suffering from serious adverse effects. Nine of 11 patients completed therapy after 19-26 months, and 2/11 patients terminated therapy after 8 and 12 months, respectively. Eight patients had remissions lasting 4-73 months. Three relapses occurred after 8, 18, and 22 months. During the induction phase, BAL cell composition changed and their activity in terms of cytokine release was suppressed. This preliminary study suggests that azathioprine may be effective as a corticosteroid-sparing agent in long-term therapy of sarcoidosis, but a much larger study is necessary to give the definitive answer.

Adult↗
PubMed1998

[A patient with muscle pain after a journey to the tropics. Myocardial involvement in proximal myotonic myopathy].

HISTORY AND ADMISSION FINDINGS: A 36-year-old man reported feeling generally unwell and experiencing shooting and tearing pain, especially in the thighs and over the precordium, just after returning from a five-week holiday in Central Africa. An active sportsman in his youth (fencing) he was known to have incomplete right bundle branch block in the ECG and a raised concentration of gamma-glutamyl transferase, of unknown aetiology. Physical examination on admission was negative except for discrete weakness on head bending and slightly delayed finger stretching after making a fist. INVESTIGATIONS: Multiple tests excluded tropical diseases. There were abnormal T waves in leads III and V1 of the ECG. Serum concentrations of creatine kinase (CK; maximally 822 U/l), gamma-glutamyl transaminase (gamma-GT; 446 U/l), glutamyl-pyruvate transaminase (GPT; 510 U/l) and of glutamate-oxalate transaminase (GOT; 108 U/l) were all elevated. Erythrocyte sedimentation rate and C-reactive protein were within normal limits. TREATMENT AND COURSE: At first the suspected diagnosis was myocarditis and he was placed on bed-rest, monitored and treated symptomatically. Because the levels of CK, gamma-GT, GPT and GOT improved only transiently, there were no signs of inflammatory disease and the muscle pains continued, biopsies of skeletal muscle and the liver were done. They revealed nonspecific liver changes and a noninflammatory myopathy. As congenital myopathy was suspected he was transferred to the neurology department where the diagnosis of proximal myotonic myopathy (PROMM) was established. CONCLUSION: We assume that an unknown viral infection triggered the illness that, in addition to the usual nonspecific symptoms, accentuated the signs of the existing multi-system proximal myotonic myopathy.

Adult↗
PubMed1998

Three novel SRY mutations in XY gonadal dysgenesis and the enigma of XY gonadal dysgenesis cases without SRY mutations.

Mutations in the Y-located testis-determining gene SRY are one cause for XY sex reversal. We have previously identified four SRY mutations in a total of 45 sex-reversed females with XY gonadal dysgenesis (XY GD). In a new sample of 16 XY GD cases, three previously undescribed SRY mutations were identified. Two are point mutations that lead to amino acid substitutions in the HMG domain of SRY, M64R, and F67V. The third SRY mutation is a single base insertion 5' to the HMG box within codon 43, converting this lysine codon to a stop codon (K43X). A total of 33 SRY mutations have so far been described that account for only 10-15% of XY GD females. A further 10-15% of these cases result from deletion of SRY due to aberrant X/Y interchange. The etiology of the remaining 70-80% of XY GD cases is still enigmatic. Possible explanations for these XY sex-reversal cases are discussed.

Adolescent↗
PubMed1997

Purification and characterization of 2-hydroxybiphenyl 3-monooxygenase, a novel NADH-dependent, FAD-containing aromatic hydroxylase from Pseudomonas azelaica HBP1.

2-Hydroxybiphenyl 3-monooxygenase (HbpA), the first enzyme of 2-hydroxybiphenyl degradation in Pseudomonas azelaica HBP1, was purified 26-fold with a yield of 8% from strain HBP1 grown on 2-hydroxybiphenyl. The enzyme was also purified from a recombinant of Escherichia coli JM109, which efficiently expressed the hbpA gene. Computer densitometry of scanned slab gels revealed a purity of over 99% for both enzyme preparations. Gel filtration, subunit cross-linking, and SDS-polyacrylamide gel electrophoresis showed that the enzyme was a homotetramer with a molecular mass of 256 kDa. Each subunit had a molecular mass of 60 kDa containing one molecule of noncovalently bound FAD. The monooxygenase had a pI of 6.3. It catalyzed the NADH-dependent ortho-hydroxylation of 2-hydroxybiphenyl to 2,3-dihydroxybiphenyl. Molecular oxygen was the source of the additional oxygen of the product. The enzyme hydroxylated various phenols with a hydrophobic side chain adjacent to the hydroxy group. All substrates effected partial uncoupling of NADH oxidation from hydroxylation with the concomitant formation of hydrogen peroxide. 2,3-Dihydroxybiphenyl, the product of the reaction with 2-hydroxybiphenyl, was a non-substrate effector that strongly facilitated NADH oxidation and hydrogen peroxide formation without being hydroxylated and also was an inhibitor. The apparent Km values (30 degrees C, pH 7.5) were 2.8 microM for 2-hydroxybiphenyl, 26.8 microM for NADH, and 29.2 microM for oxygen. The enzyme was inactivated by p-hydroxymercuribenzoate, a cysteine-blocking reagent. In the presence of 2-hydroxybiphenyl, the enzyme was partly protected against the inactivation, which was reversed by the addition of an excess of dithiothreitol. The NH2-terminal amino acid sequence of the enzyme contained the consensus sequence GXGXXG, indicative of the betaalphabeta-fold of the flavin binding site and shared homologies with that of phenol 2-hydroxylase from Pseudomonas strain EST1001 as well as with that of 2,4-dichlorophenol 6-hydroxylase from Ralstonia eutropha.

Amino Acid Sequence↗