A large meteoritic event over Antarctica ca. 430 ka ago inferred from chondritic spherules from the Sør Rondane Mountains.

Large airbursts, the most frequent hazardous impact events, are estimated to occur orders of magnitude more frequently than crater-forming impacts. However, finding traces of these events is impeded by the difficulty of identifying them in the recent geological record. Here, we describe condensation spherules found on top of Walnumfjellet in the Sør Rondane Mountains, Antarctica. Affinities with similar spherules found in EPICA Dome C and Dome Fuji ice cores suggest that these particles were produced during a single-asteroid impact ca. 430 thousand years (ka) ago. The lack of a confirmed crater on the Antarctic ice sheet and geochemical and 18O-poor oxygen isotope signatures allow us to hypothesize that the impact particles result from a touchdown event, in which a projectile vapor jet interacts with the Antarctic ice sheet. Numerical models support a touchdown scenario. This study has implications for the identification and inventory of large cosmic events on Earth.

Corticosterone in feathers of laying hens: an assay validation for evidence-based assessment of animal welfare.

Studies indicate that the evaluation of animal welfare in birds may be carried out with the measurement of the stress-related hormone corticosterone in feathers. However a standardized procedure for corticosterone measurements in feathers is lacking, a validation needs to be carried out for each new species before implementation. The aim of the present study was to establish a valid method to measure corticosterone concentrations in feathers of laying hens in a precise and repeatable manner using an established and commercially available ELISA. Validation was performed with feather pools of tail and interscapular feathers of commercial Lohmann Brown laying hens. Assessment groups, consisting of 5 replicates, were created. All replicates of an assessment group were processed at the same time. Each replicate was run in 4 repetitions by ELISA. Intra-assay and interassay CV was 7.5 and 6.4%, respectively. The serial dilution showed linearity and parallelism. Examining the hormone extraction efficiency by using different methanol volumes resulted in no statistical differences (P > 0.05). Pulverized feathers showed higher corticosterone values than minced feathers (P > 0.05). Differences were shown between 2 feather types (tail vs. interscapular feathers; P < 0.05), as well as between vane and rachis (P < 0.05). Performance of a freeze-thaw cycle led to a decrease of corticosterone concentrations in the samples. A possible effect of UV-A radiation on the stability of corticosterone in the feathers was not found (P > 0.05). With the present study, a valid protocol, feasible for analyzing feather pools of laying hens, was developed. It may provide fundamentals for further investigations on corticosterone in feathers as a noninvasive indicator to evaluate aspects of animal welfare.

Effect of pH-lowering litter amendment on animal-based welfare indicators and litter quality in a European commercial broiler husbandry.

Several studies have shown that litter moisture is a major reason for foot pad lesions (FPD) and promotes microbial growth of nitrifying bacteria. The aim of the current study was to determine the possible effects of a sodium bisulfate complex (SBS) as a litter additive on FPD, hock burn (HB), and litter parameters. Two application rates of SBS were examined in 2 experiments on a commercial farm. Two groups of about 30,000 broiler chicks each were introduced on spelt granulate spread at 700 g/m² and kept for 36 d. In the first experiment (TRT1), 250 g/m² SBS was spread on top of litter 20 h before chick placement; in the second experiment (TRT2), SBS was reduced to 150 g/m². Each experiment consisted of 1 treatment group (SBS) and a control group without treatment (CON). Both experiments were repeated once. Litter parameters (pH, percentage of dry matter), foot pad, hock condition and body weight of randomly sampled birds (n = 60 per group) were recorded weekly. Mortality rate was higher in SBS groups compared to CON groups (TRT1 2.79 vs. CON 2.03%, TRT2 2.88 vs. CON 2.27%). SBS had no effect on body weight averaged over the whole production period (P > 0.05). Incidence of FPD was significantly reduced in both groups treated with SBS compared to CON (P < 0.05), with group TRT1 showing the best results. Incidence of HB was not affected by SBS (P > 0.05) but by dry matter content (P < 0.05). At the beginning, SBS reduced litter pH to 1.7 and 2.0 in TRT1 and TRT2, respectively, compared to 6.5 and 6.7 in CON. Litter pH in TRT groups increased over time and approached pH of control groups by day 15. Results of the current study indicate that SBS treatment may be beneficial regarding foot pad health in broilers. However, further studies are needed to investigate alternative SBS application rates, and to verify the results.

Unilesional plantar mycosis fungoides treated with topical photodynamic therapy - case report and review of the literature.

BACKGROUND: Unilesional mycosis fungoides (UMF) and pagetoid reticulosis (PR) are variants of mycosis fungoides. Conventional therapy comprises surgical excision or radiotherapy, which may be associated with long-term side effects, especially when the lesion is located at a special site like the palms and soles. Therefore, alternative treatment options are needed to treat solitary lesions in the case of UMF or PR. Recently, topical photodynamic therapy (PDT) has been described to be an efficient and non-invasive therapeutical option with excellent clinical outcome. OBJECTIVE: The objective of this study was to report a 43-year-old woman with plantar UMF treated successfully with PDT, and to compare our findings with the data on PDT in UMF and PR reported in the literature. METHODS: The literature was analysed for articles on UMF and PR, respectively, treated with topical PDT. Various parameters including form of PDT and response to treatment were analysed and compared with our case. RESULTS: A total of 24 patients were documented with 24 lesions treated with PDT, either using aminolevulinic acid (ALA) or methylaminolevulinate (MAL). In average, a single lesion was treated 4 times with PDT. In 21 cases (88%), complete response could be achieved, whereas three cases (13%) showed partial remission. None of the cases showed stable or progressive disease. CONCLUSIONS: PDT is a safe, efficient and non-invasive therapeutical approach for the treatment of UMF and PR. It has no long-standing adverse events and therefore is of high therapeutic value especially in cases of UMF and PR located at special sites like the palms and soles. We propose to include topical PDT as therapeutic option for the treatment of UMF and PR in future guidelines on the management MF.

[Standardized telephone-assisted instructions on resuscitation by laypersons. Feasibility study using video-assisted quality analysis]. / Standardisierte Telefonanweisungen zur Wiederbelebung durch Laienhelfer. Videogestützte Qualitätsanalyse im Rahmen einer Machbarkeitsstudie.

BACKGROUND: Telephone-assisted instructions for cardiopulmonary resuscitation (T-CPR) are highly recommended by the current European Resuscitation Council (ERC) guidelines for resuscitation 2010. AIM: The aim of this study was to analyze the adherence of laypersons to T-CPR instructions given by dispatchers in a mock scenario. The dispatchers adapted international T-CPR instructions to local requirements. MATERIAL AND METHODS: An emergency "collapse in the office" with subsequent T-CPR was simulated for 10 volunteer, untrained administrative staff, as the only single emergency witness and 4 emergency medical service (EMS) dispatchers. Each volunteer was sent to a "colleague" who simulated a sudden cardiovascular event and collapsed unconscious during the description of symptoms. The local lay responder made an emergency call by landline telephone and was connected to the dispatcher. In the course of the simulation the "victim" was replaced by a CPR manikin. RESULTS: Every participant, i.e. 10 out of 10, assessed the victim, recognized the situation and telephoned for help. On the orders of the dispatchers 9 out of the 10 activated the loudspeaker of the telephone but 4 still continued to use the handset. The instructions for positioning were followed by all 10. Correct positioning of the victim required a median of 33[Symbol: see text]s with an interquartile range (IQR) of 30-39[Symbol: see text]s. Breathing control including instructions lasted a median of 54[Symbol: see text]s (IQR 49-60[Symbol: see text]s). Breathing was assessed by 8 out of 10 but only 2 out of 8 achieved a duration of 10[Symbol: see text]s as recommended by the ERC guidelines for resuscitation 2010. After a median of 202[Symbol: see text]s (IQR 196-241[Symbol: see text]s) chest compressions were started by 9 out of 10 and were performed for a median of 63[Symbol: see text]s (IQR 60-69[Symbol: see text]s). A correct technique was used by 7 but with a low rate of 80 compressions/min (IQR 72-86/min). The instructions for ventilation were understood by 9 out of 10. Mouth-to-mouth resuscitation was performed by 7 participants and technically correct by 5 of them. The ventilation cycle of the 7 active participants lasted for a mean of 25[Symbol: see text]s (IQR 24-30[Symbol: see text]s). The mean total duration of the timeframe analyzed was 340[Symbol: see text]s (IQR 334-368[Symbol: see text]s). CONCLUSION: The results demonstrate that the local T-CPR concept for untrained laypersons is feasible in a mock scenario. No substantial errors were observed for the majority of the untrained responders but the simulation also showed that not every emergency witness implemented the instructions according to the dispatcher's expectations. The T-CPR procedure was also more time-consuming than expected; therefore, every standardized T-CPR concept should be tested for local practicability. In accordance with current studies, the results suggest that the focus should be on compression-only CPR instructions in urban settings. Dispatcher education in T-CPR should incorporate videotaped mock-up scenarios with untrained local laypersons.

Enzymatic hydrolysis of PTT polymers and oligomers.

Oligomers and polymers (film, fabrics) of the linear aromatic polyester poly(trimethylene terephthalate) (PTT) were treated with polyesterases from Thermomyces lanuginosus, Penicillium citrinum, Thermobifida fusca and Fusarium solani pisi. The cutinase from T. fusca was found to release the highest amounts of hydrolysis products from PTT materials and was able to open and hydrolyse a cyclic PTT dimer according to RP-HPLC-UV detection. In contrast, the lipase from T. lanuginosus also showed activity on the PTT fibres and on bis(3-hydroxypropyl) terephthalate (BHPT) but was not able to hydrolyse the polymer film, mono(3-hydroxypropyl) terephthalate (MHPT) nor the cyclic dimer of PTT. As control enzymes inhibited with mercury chloride were used. Surface hydrophilicity changes were investigated with contact angle measurements and the degree of crystallinity changes were determined with DSC.

Randomised controlled trials of homeopathy in hyperactive children: treatment procedure leads to an unconventional study design. Experience with open-label homeopathic treatment preceding the Swiss ADHD placebo controlled, randomised, double-blind, cross-over trial.

BACKGROUND: Treatment of patients with attention deficit hyperactivity disorder (ADHD) with homeopathy is difficult. The Swiss randomised, placebo controlled, cross-over trial in ADHD patients (Swiss ADHD trial) was designed with an open-label screening phase prior to the randomised controlled phase. During the screening phase, the response of each child to successive homeopathic medications was observed until the optimal medication was identified. Only children who reached a predefined level of improvement participated in the randomised, cross-over phase. Although the randomised phase revealed a significant beneficial effect of homeopathy, the cross-over caused a strong carryover effect diminishing the apparent difference between placebo and verum treatment. METHODS: This retrospective analysis explores the screening phase data with respect to the risk of failure to demonstrate a specific effect of a randomised controlled trial (RCT) with randomisation at the start of the treatment. RESULTS: During the screening phase, 84% (70/83) of the children responded to treatment and reached eligibility for the randomised trial after a median time of 5 months (range 1-18), with a median of 3 different medications (range 1-9). Thirteen children (16%) did not reach eligibility. Five months after treatment start, the difference in Conners Global Index (CGI) rating between responders and non-responders became highly significant (p = 0.0006). Improvement in CGI was much greater following the identification of the optimal medication than in the preceding suboptimal treatment period (p < 0.0001). CONCLUSIONS: Because of the necessity of identifying an optimal medication before response to treatment can be expected, randomisation at the start of treatment in an RCT of homeopathy in ADHD children has a high risk of failure to demonstrate a specific treatment effect, if the observation time is shorter than 12 months.

Neuropsychological problems after paediatric stroke: two year follow-up of Swiss children.

AIM: The aim of this study was to obtain information about neurological and cognitive outcome for a population-based group of children after paediatric ischaemic stroke. METHODS: Data from the Swiss neuropaediatric stroke registry (SNPSR), from 1.1.2000 to 1.7.2002, including children (AIS 1) and neonates (AIS 2). At 18-24 months after a stroke, a follow-up examination was performed including a history, neurological and neuropsychological assessment. RESULTS: 33/48 children (22 AIS 1, 11 AIS 2) participated in the study. Neurological outcome was good in 16/33. After childhood stroke mean IQ levels were normal (94), but 6 children had IQ < 85 (50-82) and neuropsychological problems were present in 75%. Performance IQ (93) was reduced compared to verbal IQ (101, p = 0.121) due to problems in the domain of processing speed (89.5); auditory short-term memory was especially affected. Effects on school career were common. Outcome was worse in children after right-sided infarction. Children suffering from stroke in mid-childhood had the best prognosis. There was no clear relationship between outcome and localisation of the lesion. After neonatal stroke 7/11 children showed normal development and epilepsy indicated a worse prognosis in the remaining 4. CONCLUSION: After paediatric stroke neuropsychological problems are present in about 75% of children. Younger age at stroke as well as an emergence of epilepsy were predictors for worse prognosis.

[Severe lead poisoning due to Ayurvedic indian plant medicine]. / Chronische Bleivergiftung durch ayurvedische Heilpillen.

HISTORY AND CLINICAL FINDINGS: A 39-year-old woman with a history of slowly progressive muscular dystrophia was transferred to us for further evaluations of a hypochromic, microcytic anaemia. The patient complained about progressive muscle weakness, loss of appetite and constipation, sleep disorders as well as muscle and back pain. Clinical examination revealed a tetraparesis without any detectable muscle reflexes and atrophic muscles of the extremities. A bilateral radial paresis was found with a loss of power. INVESTIGATIONS: She presented with a hypochromic, microcytic anaemia with a haemoglobin of 7.9 g/dl. Re-evaluation of her peripheral blood smear showed basophilic stippling of the erythrocytes. Bone marrow biopsy revealed a marked dyserythropoiesis with 50% ring sideroblasts. After the examination of the bone marrow, the blood lead level was found to be grossly elevated up to 880 microg/l. DIAGNOSIS: Re-evaluation of the patient's history revealed that she had been to India for an Ayurvedic treatment approach to improve her muscle dystrophia. She had taken regularly 4 different natural plant pills which she had bought in an Ayurvedic health centre. Toxicologic analysis of these pills revealed one to have a lead concentration of 50.4 mg/g. TREATMENT AND COURSE: The patient was treated with 16 infusions of sodium-EDTA followed by a 4-week treatment with dimercaptopropionic acid orally. Her neurological condition improved and the radial paresis resolved gradually so that she could return to work. Her haematological parameters normalized. CONCLUSION: This case report underscores the importance, while asking patients for their drug history, to ask additionally if natural plant medicine is taken or applied regularly. The report reveals that Ayurvedic pills from India may have a high concentration of lead and may cause severe poisoning.

Isolation and characterization of a soluble NADPH-dependent Fe(III) reductase from Geobacter sulfurreducens.

NADPH is an intermediate in the oxidation of organic compounds coupled to Fe(III) reduction in Geobacter species, but Fe(III) reduction with NADPH as the electron donor has not been studied in these organisms. Crude extracts of Geobacter sulfurreducens catalyzed the NADPH-dependent reduction of Fe(III)-nitrilotriacetic acid (NTA). The responsible enzyme, which was recovered in the soluble protein fraction, was purified to apparent homogeneity in a four-step procedure. Its specific activity for Fe(III) reduction was 65 micromol. min(-1). mg(-1). The soluble Fe(III) reductase was specific for NADPH and did not utilize NADH as an electron donor. Although the enzyme reduced several forms of Fe(III), Fe(III)-NTA was the preferred electron acceptor. The protein possessed methyl viologen:NADP(+) oxidoreductase activity and catalyzed the reduction of NADP(+) with reduced methyl viologen as electron donor at a rate of 385 U/mg. The enzyme consisted of two subunits with molecular masses of 87 and 78 kDa and had a native molecular mass of 320 kDa, as determined by gel filtration. The purified enzyme contained 28.9 mol of Fe, 17.4 mol of acid-labile sulfur, and 0.7 mol of flavin adenine dinucleotide per mol of protein. The genes encoding the two subunits were identified in the complete sequence of the G. sulfurreducens genome from the N-terminal amino acid sequences derived from the subunits of the purified protein. The sequences of the two subunits had about 30% amino acid identity to the respective subunits of the formate dehydrogenase from Moorella thermoacetica, but the soluble Fe(III) reductase did not possess formate dehydrogenase activity. This soluble Fe(III) reductase differs significantly from previously characterized dissimilatory and assimilatory Fe(III) reductases in its molecular composition and cofactor content.

Isolation and characterization of a veratrol:corrinoid protein methyl transferase from Acetobacterium dehalogenans.

From 3-methoxyphenol-grown cells of Acetobacterium dehalogenans, an inducible enzyme was purified that mediated the transfer of the methyl groups of veratrol (1,2-dimethoxybenzene) to a corrinoid protein enriched from the same cells. In this reaction, veratrol was converted via 2-methoxyphenol to 1,2-dihydroxybenzene. The veratrol:corrinoid protein methyl transferase, designated MTIver, had an apparent molecular mass of about 32 kDa. With respect to the N-terminal amino acid sequence and other characteristics, MTIver is different from the vanillate:corrinoid protein methyl transferase (MTIvan) isolated earlier from the same bacterium. For the methyl transfer from veratrol to tetrahydrofolate, two additional protein fractions were required, one of which contained a corrinoid protein. This protein was not identical with the corrinoid protein of the vanillate O-demethylase system. However, the latter corrinoid protein could also serve as methyl acceptor for the veratrol:corrinoid protein methyl transferase. MTIver catalyzed the demethylation of veratrol, 3,4-dimethoxybenzoate, 2-methoxyphenol, and 3-methoxyphenol. Vanillate (3-methoxy-4-hydroxybenzoate), 2-methoxybenzoate, or 4-methoxybenzoate could not serve as substrates.

Outcome of patients with ventricular assist devices and acute renal failure requiring renal replacement therapy.

The significance of acute renal failure (ARF) for patients treated with a ventricular assist device (VAD) is uncertain. There is little information on the outcome of patients who require renal replacement therapy during treatment with a VAD. A retrospective review was undertaken to evaluate the impact of renal failure requiring renal replacement therapy on such patients. Studied were 227 patients who were supplied with a VAD at the German Heart Institute Berlin. Fifty-five patients required renal replacement therapy during treatment with a VAD. These were compared with patients not needing renal replacement therapy (ARF and non-ARF groups). Significant differences for the end points of survival, heart transplantation, and discharge from hospital were observed in patients with ARF (p < 0.01). Survival was then analyzed according to indications for treatment with a VAD (bridge to transplantation or cardiac recovery after cardiotomy, transplantation, myocardial infarction, myocarditis, and endocarditis). Survival for bridge-to-transplantation patients was clearly influenced in a negative way by ARF (p < 0.01). For cardiac recovery patients, only a small difference in survival was observed (p = 0.05). We conclude that ARF is a negative predictor for bridge-to-transplantation patients. For cardiac recovery patients the impact of ARF on survival is marginally significant.

Radiologic anatomy of ventricular assist devices.

Ventricular assist devices (VAD) allow for long-term circulatory support of patients with end-stage heart failure. With the increasing duration of circulatory support, diagnostic imaging plays an important role in the management of patients on a VAD. The aim of our review was to analyze the radiologic features of different VADs. From 1987 to 1996, 319 patients (mean age 42 years, range 3 to 74 years) were treated with a VAD. A Berlin Heart VAD was implanted in 263 of the patients, the univentricular Baxtor Novacor was implanted in three patients, and the univentricular CI Heartmate was implanted in 19 patients. All patients were studied by serial chest radiographs. In addition, 70 patients underwent computed tomography (CT), and five patients underwent electron beam CT. The Berlin Heart VAD was used as a biventricular support system in 218 patients. In all cases, the position of the wire-directed cannulae was identified on the chest radiographs, while the exact position of the cannula tip could be visualized by CT only. The plastic cannulae of both the Novacor and the Heartmate were not discernible on radiographs, but required CT for evaluation. Computed tomography also resolved the metal components of the pumps. The titanium-made pump housing of the Heartmate caused beam-hardening artefacts that might conceal fluid accumulations in the pump pocket. Computed tomography is the standard of reference for examinations of cannula position, pump position, and pump components of ventricular assist devices.

O-demethylase from Acetobacterium dehalogenans--cloning, sequencing, and active expression of the gene encoding the corrinoid protein.

The ether-cleaving O-demethylase from the strictly anaerobic homoacetogen Acetobacterium dehalogenans catalyses the methyltransfer from 4-hydroxy-3-methoxy-benzoate (vanillate) to tetrahydrofolate. In the first step a vanillate :corrinoid protein methyltransferase (methyltransferase I) mediates the methylation of a 25-kDa corrinoid protein with the cofactor reduced to cob(I)alamin. The methyl group is then transferred to tetrahydrofolate by the action of a methylcorrinoid protein:tetrahydrofolate methyltransferase (methyltransferase II). Using primers derived from the amino-terminal sequences of the corrinoid protein and the vanillate:corrinoid protein methyltransferase (methyltransferase I), a 723-bp fragment was amplified by PCR, which contained the gene odmA encoding the corrinoid protein of O-demethylase. Downstream of odmA, part of the odmB gene encoding methyltransferase I was identified. The amino acid sequence deduced from odmA showed about 60% similarity to the cobalamin-binding domain of methionine synthase from Escherichia coli (MetH) and to corrinoid proteins of methyltransferase systems involved in methanogenesis from methanol and methylamines. The sequence contained the DXHXXG consensus sequence typical for displacement of the dimethylbenzimidazole base of the corrinoid cofactor by a histidine from the protein. Heterologous expression of odmA in E. coli yielded a colourless, oxygen-insensitive apoprotein, which was able to bind one mol cobalamin or methylcobalamin/mol protein. Both of these reconstituted forms of the protein were active in the overall O-demethylation reaction. OdmA reconstituted with hydroxocobalamin and reduced by titanium(III) citrate to the cob(I)alamin form was methylated with vanillate by methyltransferase I in an irreversible reaction. Methylcobalamin carrying OdmA served as methyl group donor for the methylation of tetrahydrofolate by methyltransferase II. This reaction was found to be reversible, since methyltranSferase II also catalysed the methylation of cob(I)alamin containing OdmA with methyltetrahydrofolate.

Recognition of two overlapping CTL epitopes in HIV-1 p17 by CTL from a long-term nonprogressing HIV-1-infected individual.

HIV-1 infection has been shown to elicit strong CTL responses in some infected persons, but few data are available regarding the relationship between targeted epitopes and in vivo viral quasispecies. In this study, we examined the CTL response in a person infected for 15 yr with a CD4 count persistently >500 cells/microl. The dominant in vivo activated CTL response was directed against two overlapping Gag CTL epitopes in an area of p17 known to be essential for viral replication. The 9-mer SLYNTVATL (amino acids 77-85) was recognized in conjunction with HLA-A2, whereas the overlapping 8-mer TLYCVHQR (amino acids 83-91) was recognized by HLA-A11-restricted CTL. Analysis of in vivo virus sequences both in PBMC and plasma revealed the existence of sequence variation in this region, which did not affect viral replication in vitro, but decreased recognition by the A11-restricted CTL response, with maintenance of the A2-restricted response. These results indicate that an essential region of the p17 protein can be simultaneously targeted by CTL through two different HLA molecules, and that immune escape from CTL recognition can occur without impairing viral replication. In addition, they demonstrate that Ag processing can allow for presentation of overlapping epitopes in the same infected cell, which can be affected quite differently by sequence variation.

O-demethylase from Acetobacterium dehalogenans--substrate specificity and function of the participating proteins.

The ether-cleaving O-demethylase isolated from syringate-grown cells of Acetobacterium dehalogenans (formerly named strain MC) consists of four proteins, components A, B, C and D. The enzyme system converts only phenyl methyl ethers with a hydroxyl group in the ortho position to the methoxyl moiety. The presence of a carboxyl group in the aromatic compound was not required for O-demethylase reaction. Component B mediated the conversion of vanillate to 3,4-dihydroxybenzoate in the presence of the Ti(III)-reduced corrinoid-containing component A. After addition of component D and tetrahydrofolate, methyl tetrahydrofolate was formed from vanillate in stoichiometric amounts. Titanium(III) citrate as a reductant could be replaced by H2, methyl viologen or ferredoxin, partially purified hydrogenase, purified component C obtained from A. dehalogenans, and ATP. From these findings, it was deduced that component B serves as vanillate:corrinoid protein methyltransferase (methyltransferase I) mediating the methyl transfer from vanillate to the reduced corrinoid protein component A. Component D functions as methylcorrinoid protein:tetrahydrofolate transferase (methyltransferase II). The role of component C is probably that of an activating protein reversing accidental oxidation of the protein-bound cob(I)alamin to cob(II)alamin in the presence of ATP and reducing equivalents supplied by the enzymatic oxidation of hydrogen.

Isolation of O-demethylase, an ether-cleaving enzyme system of the homoacetogenic strain MC.

The O-demethylase of the methylotrophic homoacetogenic bacterium strain MC was purified to apparent homogeneity. The enzyme system consisted of four different components that were designated A, B, C, and D according to their elution sequence from the anionic-exchange chromatography column. All four components were essentially required for catalysis of the transfer of the methyl group from phenyl methyl ethers to tetrahydrofolate. According to gel filtration and SDS-PAGE, components A and B were monomers with apparent molecular masses of approximately 26 kDa (subunit 25 kDa) and 36 (subunit 41 kDa), respectively; component C appeared to be a trimeric protein (195 kDa, subunit 67 kDa); and component D was probably a dimer (64 kDa, subunit 30 kDa). Component A contained one corrinoid per monomer. In crude extracts, component D appeared to be the rate-limiting protein for the complete methyl transfer reaction. Additional requirements for the reaction were ATP and low-potential reducing equivalents supplied by either titanium(III) citrate or H2 plus hydrogenase purified from strain MC.