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At least 19 recordsLinked to original sources

PubMed1989

Measurement of propionate turnover in vivo using sodium [2H5]propionate and sodium [13C]propionate.

The outcome for children with inherited disorders of propionate metabolism is poor. To facilitate development of improved treatment in these conditions, we described techniques for the estimation of the rate of production and removal of propionate in vivo. Propionate turnover was determined in 4 healthy adults using continuous infusions of sodium [2H5]propionate and sodium [13C]propionate. The mean fasting plasma propionate concentration measured by a sensitive technique employing high performance liquid chromatography, following a two-stage extraction procedure and derivatisation with bromophenacyl bromide, was 3.3 mumol/l (SD 0.5). The isotopic enrichment of the bromophenacyl propionate derivative was measured by gas chromatography/mass spectrometry and mean propionate turnover was calculated to be 17.6 mumol/kg per h (SD 5.9). These methods allow rapid (less than 3 h) assessment of propionate turnover in man and are suitable for application in children with inherited disorders of propionate metabolism.

Adult↗

PubMed1991

Dermatopharmacologic investigations of halobetasol propionate in comparison with clobetasol 17-propionate.

Both halobetasol propionate and clobetasol 17-propionate exerted very marked antiinflammatory, antiproliferative, and vasoconstrictive effects during evaluation in a range of dermatopharmacologic models. Halobetasol propionate was distinctly more potent than clobetasol 17-propionate in the ultraviolet-induced dermatitis inhibition assay in guinea pigs and in the rat model of oxazolone-induced late inflammatory reaction. Halobetasol propionate was slightly more potent than clobetasol 17-propionate in inhibiting croton oil-induced ear edema in rats and mice and in the mouse model of oxazolone-induced early inflammatory reaction. In the cotton-pellet granuloma assay in rats and the epidermal hyperplasia inhibition assay in guinea pigs, halobetasol propionate was distinctly superior to clobetasol 17-propionate. There was a trend in favor of halobetasol propionate in the cutaneous vasoconstriction assay performed in volunteers with ethanol solutions of halobetasol propionate and clobetasol 17-propionate. In a further vasoconstriction assay, performed with a 0.05% concentration of both halobetasol propionate and clobetasol 17-propionate in cream and ointment formulations, halobetasol propionate ointment yielded the highest blanching score. In a hypothalamic-pituitary-adrenal axis study in volunteers, effects of 0.05% halobetasol propionate ointment and 0.05% clobetasol 17-propionate ointment on serum cortisol levels were similar. The overall efficacy trends demonstrated in these dermatopharmacologic studies are in agreement with predictions made from corticosteroid structure and activity relationships and the results of two clinical trials comparing halobetasol propionate and clobetasol 17-propionate ointments in the treatment of plaque psoriasis.

Animals↗

PubMed1988

Kinetics of metabolism of glucose, propionate and CO2 in steers as affected by injecting phlorizin and feeding propionate.

Effects of injecting phlorizin subcutaneously and/or feeding propionate on metabolism of glucose, propionate and CO2 were determined for four steers used in a 4 x 4 Latin square design. Isotope dilution techniques were used to determine a four-pool kinetic solution for the flux of carbon among plasma glucose, rumen propionate, blood CO2 and rumen CO2. Injecting 1 g of phlorizin twice daily for 19 d resulted in 7.1 mol glucose C/d being excreted in urine. The basal glucose production of 13.4 mol C/d was increased to 17.9 mol C/d with phlorizin. There was no change in glucose oxidation or propionate production. The percentage of plasma glucose derived from propionate was unaffected by phlorizin, but 54 +/- 0.4% of total propionate was converted to plasma glucose during phlorizin treatment versus 40 +/- 0.6% during the basal treatment. When propionate was fed (18.3 mol C/d) glucose production increased to 21.2 mol C/d from the basal value of 13.4 mol C/d, and propionate oxidation to CO2 increased to 14.9 mol C/d from the basal value of 4.1 mol C/d. Glucose derived from propionate was 43 +/- 5% for the basal treatment and 67 +/- 3% during propionate feeding. The percentage of propionate converted to plasma glucose and blood and rumen CO2 was not affected by feeding propionate. An increased need for glucose, because of glucose excretion during phlorizin treatment, caused an increased utilization of propionate for gluconeogenesis, but an increased availability of propionate caused an increase in glucose production without affecting the relative distribution of carbon from propionate.

Animals↗

PubMed1990

Sources of propionate in inborn errors of propionate metabolism.

Amino acids are widely regarded as the most important sources of propionate in disorders of propionate metabolism. Propionate production was measured in the fasting state by continuous infusion of sodium [1-13C]propionate in three children with methylmalonic acidemia (MMA) and three with propionic acidemia (PA). The contribution of isoleucine, valine, threonine, and methionine catabolism to total propionate production was estimated by extrapolation from the hydroxylation of phenylalanine determined by a continuous-infusion [2H5]phenylalanine technique. The contribution of gut bacterial propionate production was determined by measuring total propionate production before and after treatment with oral metronidazole (10 to 20 mg/kg/d for 1 week). Amino acid catabolism accounted for a mean of 51.7% (range, 24.5% to 66.4%) of total propionate production. The mean decrease in propionate production after metronidazole was 22.2% +/- 8.5 (P less than .02); this percentage is likely to represent the minimum propionate production attributable to gut bacteria. Approximately 30% of total propionate production was unaccounted for, and is likely to arise primarily from odd-chain fatty acid catabolism in the fasting state. These results indicate that sources of propionate other than from protein catabolism are important in disorders of propionate metabolism, and explain the generally disappointing response to dietary protein restriction.

Amino Acids↗

PubMed1965

METABOLISM OF PROPIONATE BY SHEEP LIVER. OXIDATION OF PROPIONATE BY HOMOGENATES.

1. The rate and stability to aging of the metabolism of propionate by sheep-liver slices and sucrose homogenates were examined. Aging for up to 20min. at 37 degrees in the absence of added substrate had little effect with slices, whole homogenates or homogenates without the nuclear fraction. 2. Metabolism of propionate by sucrose homogenates was confined to the mitochondrial fraction, but the mitochondrial supernatant (microsomes plus cell sap) stimulated propionate removal. 3. The rate of propionate metabolism by liver slices was higher in a high potassium phosphate-bicarbonate medium [0.88(+/-s.e.m. 0.16)mumole/mg. of N/hr.] than in Krebs-Ringer bicarbonate medium [0.44(+/-s.e.m. 0.13)mumole/mg. of N/hr.]. 4. Metabolism of propionate by sucrose homogenates freed from nuclei was dependent on the presence of oxygen, carbon dioxide and ATP. Propionate removal was stimulated 250% by Mg(2+) ions and 670% by cytochrome c. 5. In the complete medium 2.39(+/-s.e.m. 0.15)mumoles of propionate were consumed/mg. of N/hr. 6. The ratio of oxygen consumption to propionate utilization was sufficient to account for the complete oxidation of half the propionate consumed. 7. The only products detected under these conditions were succinate, fumarate and malate. Propionate had no effect on the production of lactate from endogenous sources and did not itself give rise to lactate. 8. Methylmalonate did not accumulate when propionate was metabolized and was not oxidized. It was detected as an intermediate in the conversion of propionyl-CoA into succinate. The rate of this reaction sequence was adequate to account for the rate of propionate metabolism by sucrose homogenates or slices, provided that the rate of formation of propionyl-CoA was not limiting. 9. The methylmalonate pathway was predominantly a mitochondrial function. 10. The metabolism of propionate appeared to be dependent on active oxidative phosphorylation.

Acyl Coenzyme A↗

PubMed1993

Effects of acetate, propionate, and butyrate on the thermophilic anaerobic degradation of propionate by methanogenic sludge and defined cultures.

The effects of acetate, propionate, and butyrate on the anaerobic thermophilic conversion of propionate by methanogenic sludge and by enriched propionate-oxidizing bacteria in syntrophy with Methanobacterium thermoautotrophicum delta H were studied. The methanogenic sludge was cultivated in an upflow anaerobic sludge bed (UASB) reactor fed with propionate (35 mM) as the sole substrate for a period of 80 days. Propionate degradation was shown to be severely inhibited by the addition of 50 mM acetate to the influent of the UASB reactor. The inhibitory effect remained even when the acetate concentration in the effluent was below the level of detection. Recovery of propionate oxidation occurred only when acetate was omitted from the influent medium. Propionate degradation by the methanogenic sludge in the UASB reactor was not affected by the addition of an equimolar concentration (35 mM) of butyrate to the influent. However, butyrate had a strong inhibitory effect on the growth of the propionate-oxidizing enrichment culture. In that case, the conversion of propionate was almost completely inhibited at a butyrate concentration of 10 mM. However, addition of a butyrate-oxidizing enrichment culture abolished the inhibitory effect, and propionate oxidation was even stimulated. All experiments were conducted at pH 7.0 to 7.7. The thermophilic syntrophic culture showed a sensitivity to acetate and propionate similar to that of mesophilic cultures described in the literature. Additions of butyrate or acetate to the propionate medium had no effect on the hydrogen partial pressure in the biogas of an UASB reactor, nor was the hydrogen partial pressure in propionate-degrading cultures affected by the two acids.(ABSTRACT TRUNCATED AT 250 WORDS)

Acetates↗

PubMed1993

[13C]propionate oxidation in wild-type and citrate synthase mutant Escherichia coli: evidence for multiple pathways of propionate utilization.

The metabolism of propionate was examined in wild-type Escherichia coli and cells lacking citrate synthase by high-resolution 13C n.m.r. Spectra of cell extracts from wild-type E. coli show that glutamate becomes highly enriched in 13C when 13C-enriched propionate is the sole carbon source. No glutamate labelling was detected when the tricarboxylic acid cycle was blocked either by deletion of citrate synthase or by inhibition of succinate dehydrogenase by malonate. The 13C fractional enrichment in glutamate C-2, C-3 and C-4 in wild-type cells was quantitatively and qualitatively different when [2-13C]propionate as opposed to [3-13C]propionate was supplied. Approximately equal labelling occurred in the C-2, C-3 and C-4 positions of glutamate when [3-13C]propionate was available, and multiplets due to carbon-carbon spin-spin coupling were observed. However, in cells supplied with [2-13C]propionate, very little 13C appeared in the glutamate C-4 position, and the remaining glutamate resonances all appeared as singlets. The unequal and non-identical labelling of glutamate in cells supplied with [2-13C]- as opposed to [3-13C]propionate is consistent with the utilization of propionate by E. coli via two pathways, oxidation of propionate to pyruvate and carboxylation of propionate to succinate. These intermediates are further metabolized to glutamate by the action of the tricarboxylic acid cycle. The existence of an organized tricarboxylic acid cycle is discussed as a consequence of the ability to block utilization of propionate in tricarboxylic acid-cycle-defective E. coli.

Acetyl Coenzyme A↗

PubMed2000

Effects of dietary inclusion of chromium propionate and calcium propionate on glucose disposal and gastrointestinal development in dairy calves.

In experiment 1, 21 male Holstein calves (43.9 kg) were fed only milk replacer at 1.4% of their body weight as dry matter for 6 wk. Dietary treatments included a commercial milk replacer (22% protein, 15% fat) containing (dry basis) either 6.4% Ca propionate or 6.4% dextrose (control) and either 0 or 0.5 mg/kg of supplemental Cr as Cr propionate. Neither Cr nor Ca propionate affected body weight gain; however, Ca propionate tended to increase the growth of the entire foregut measured after slaughter at 6 wk of age. A Minimal Model glucose tolerance test indicated that insulin sensitivity was not affected by treatment. However, calves fed Cr had higher glucose disappearance indexes than controls when propionate was not fed (0.013 vs. 0.019 units) but similar clearance when propionate was included (0.018 vs. 0.018 units, Cr x P interaction). The area under the glucose response curves after propionate-loading tests was much greater for calves fed the Cr versus control replacer when propionate was not present; however, when propionate was included, the response was less dramatic. In experiment 2, 25 Holstein calves were used to study performance and metabolic responses when milk replacer, and then postweaning starter, were supplemented with 0.5 mg/kg of Cr as Cr propionate. The metabolic responses of these calves were not affected by treatment. Overall, combined data suggested that supplemental Cr may improve glucose effectiveness; however, these responses seemed to be attenuated by supplemental propionate.

Animal Feed↗

PubMed1990

In vivo propionate oxidation as a prognostic indicator in disorders of propionate metabolism.

Biochemical markers such as plasma and urinary metabolite concentrations and in vitro enzyme activity are of limited prognostic value in the most common disorders of propionate metabolism, methylmalonic acidaemia (MMA) and propionic acidaemia (PA). In vivo propionate oxidation was compared with conventional prognostic measures as predictors of clinical severity in seven children with MMA and six with PA. Propionate oxidation was measured using a continuous infusion of [1-13C]propionate and was expressed as the rate of appearance of 13CO2 as a percentage of the propionate infusion rate. Children with MMA (mean oxidation 51.2%, range 17.5-91.6, P less than 0.05) and with PA (mean oxidation 36.3%, range 3.0-91.1, P = NS) oxidised substantially less propionate than controls (mean oxidation 81.9%, range 69.4-101.0, n = 5). Percentage oxidation was a better predictor of the clinical severity score (r = 0.75, P less than 0.01) than was in vitro enzyme activity, plasma propionate or methylmalonate concentration or urinary metabolite excretion. Studies were repeated after an interval of 1-3 weeks in six of the subjects; the percentage oxidation in each subject was virtually unchanged between studies (coefficient of variation 8.6%). These results suggest that in vivo oxidation measurements using [13C]propionate are both reproducible and prognostically useful in disorders of propionate metabolism.

Adolescent↗

PubMed1994

Fluticasone propionate aerosol for the treatment of adults with mild to moderate asthma. The Fluticasone Propionate Asthma Study Group.

BACKGROUND: Recent emphasis on the control of airway inflammation in asthma highlights the need for safe and effective antiinflammatory agents. Fluticasone propionate is one of the most potent antiinflammatory corticosteroids developed to date. OBJECTIVE: This study assessed the safety and efficacy of fluticasone propionate aerosol in the treatment of mild to moderate asthma. METHODS: Fluticasone propionate aerosol (25, 100, or 500 micrograms twice daily) or placebo was given for as long as 8 weeks to adults with mild to moderate asthma in a randomized, double-blind, parallel-group study. Patients were removed from the study if they showed predefined signs of worsening asthma. RESULTS: Sixty-three percent of placebo-treated patients and 23%, 13%, and 4% of patients treated with fluticasone propionate 25, 100, and 500 micrograms twice daily, respectively, were removed from the study. Mean forced expiratory volume in 1 second, forced vital capacity, and forced expiratory flow at midexpiratory phase at weekly visits throughout the study demonstrated that fluticasone propionate was more efficacious than placebo in maintaining asthma control. Measurements of peak expiratory flow and symptom scores significantly improved and nighttime awakenings and albuterol use to treat symptoms significantly declined in fluticasone propionate-treated groups relative to the placebo-treated group. Differences among fluticasone propionate groups for these variables were not statistically significant. Incidence and severity of adverse events were similar across groups. Fluticasone propionate did not affect morning or stimulated plasma cortisol concentrations, although slight, transient reductions in urinary free cortisol and urinary 17-hydroxy steroids occurred in the group receiving 500 micrograms fluticasone propionate twice daily. CONCLUSION: These data indicate that fluticasone propionate provides safe and effective treatment for mild to moderate asthma.

Administration, Topical↗

PubMed1982

Stimulation of ketogenesis by propionate in isolated rat hepatocytes: an explanation for ketosis associated with propionic acidaemia and methylmalonic acidaemia?

The effect of propionate on ketone body production from oleate and octanoate in isolated rat hepatocytes was studied. Propionate (5 mmol/l) stimulated ketogenesis from oleate and octanoate, although the effect was more pronounced when octanoate was used as substrate. Propionate decreased CO2 production from fatty acids, suggesting that propionate inhibited the oxidation of free fatty acid carbons through the tricarboxylic acid cycle. Our results suggest that propionate enhanced ketogenesis as a consequence of the decrease in the rate of the tricarboxylic acid cycle, caused by propionate and/or its derivatives. The stimulation of ketogenesis caused by propionate is discussed as the possible cause of ketosis associated with propionic acidaemia and methylmalonic acidaemia.

Acidosis↗

PubMed1992

Performance of feedlot steers fed diets containing laidlomycin propionate or monensin plus tylosin, and effects of laidlomycin propionate concentration on intake patterns and ruminal fermentation in beef steers during adaptation to a high-concentrate diet.

Two hundred eighty-eight beef steers (British x Continental x Brahman) were fed a 90% concentrate diet containing either no ionophore (control), laidlomycin propionate at either 6 or 12 mg/kg of dietary DM, or monensin plus tylosin (31 and 12 mg/kg of DM, respectively). Neither of the two levels of laidlomycin propionate nor monensin plus tylosin affected (P greater than .10) ADG or feed:gain ratio. Monensin plus tylosin reduced (P less than .01) daily DMI for the 161-d trial period compared with the other three treatments. Laidlomycin propionate at 6 mg/kg increased (P less than .05) DMI relative to the control, laidlomycin propionate at 12 mg/kg, and monensin plus tylosin diets during the 2nd wk of the trial and from d 57 to 84. Treatments did not affect carcass measurements. In a second experiment, 12 ruminally cannulated steers were fed diets containing no ionophore or laidlomycin propionate at either 6 or 12 mg/kg of DM. Samples were obtained for two consecutive days while the dietary concentrate level was 75%, after which the diet was switched abruptly to 90% concentrate, and samples were collected on several days during a 21-d period. The rate at which steers consumed their daily allotment of feed was not altered markedly by laidlomycin propionate. Likewise, laidlomycin propionate did not affect total ruminal VFA concentrations or proportions. Ruminal concentrations of D-lactate were reduced (P less than .10) by 6 but not by 12 mg/kg of laidlomycin propionate.(ABSTRACT TRUNCATED AT 250 WORDS)

Ammonia↗

PubMed1991

Metabolism of 1-13C-propionate in vivo in patients with disorders of propionate metabolism.

Metabolism of propionate in human subjects was studied using bolus administration of 1-13C-propionate i.v. or orally. The study population consisted of five patients with propionic acidemia (PA), eight with methylmalonic acidemia (MMA; four responsive to vitamin B12), one each with multiple carboxylase deficiency and transcobalamin-II deficiency, and five healthy volunteers. Concentrations of 1-13C-propionate were measured in blood in three patients with PA, two with MMA, and two controls. Breath samples were obtained at intervals during 3 h after the dose, isotopic enrichment of 13CO2 was measured, and the cumulative percentage of recovery of 13C was calculated from the individual's predicted resting energy expenditure. Recovery of 13CO2 and half-time of 1-13C-propionate in PA were significantly less than normal. The same parameters in MMA were below normal, but significantly greater than in PA. Recovery of 13CO2 was well correlated with clinical severity in PA, but did not correlate in MMA. Differences between MMA and PA may indicate different distribution of propionate pools, differences in inducibility of residual enzyme activities, or an alternate pathway for decarboxylation of propionate available in MMA but not PA. Only one patient with PA demonstrated increased 13CO2 production during biotin treatment. In a B12-responsive MMA patient, no differences were noted within 2 d of initiating treatment with B12, but there was an increase in 13CO2 production after 4 mo. Recovery of 13CO2 was normal in the patient with transcobalamin-II deficiency before and after treatment with vitamin B12.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗

PubMed1984

Urinary excretion of acetate and propionate by the Holstein cow as affected by physiological state and propionate infusion.

Daily urinary excretion of acetate and propionate was determined for 13 Holstein cows fed for ad libitum consumption a 40% soy-corn concentrate: 60% corn silage diet prepartum and 60% concentrate: 40% silage diet postpartum. Daily excretion of acetate did not differ between periods corresponding to -3, 7, and 11 wk postpartum. Cows excreted more propionic acid at 7 and 11 wk postpartum than at 3 wk prepartum. However, propionic acid excretion did not differ between the two postpartum periods. Propionic acid excretion was not associated with intake of feed during lactation. Rapid intrajugular infusion of propionate (2.5 mmol/kg) increased propionate excretion at -3 and 7 wk postpartum and acetate excretion at 7 wk postpartum. Under physiological conditions urinary excretion of acetate and propionate does not represent a meaningful energy loss.

Acetates↗

PubMed1994

Contribution of odd-chain fatty acid oxidation to propionate production in disorders of propionate metabolism.

Whole-body propionate and protein kinetics and energy substrate metabolism were studied in five metronidazole-treated patients with propionic or methylmalonic acidemias by the use of a primed, 4-h constant infusion of [1-13C]propionate and L-[O-2H5]phenylalanine combined with indirect calorimetry. Measurements were performed during fasting and carbohydrate feeding, successively, to assess the contribution of odd-chain fatty acid oxidation to total propionate production. Fat oxidation decreased from 490 +/- 179 to 57 +/- 49 mumol.kg-1.h-1 (P < 0.05) as a result of feeding. Propionate appearance rate was 38.6 +/- 8 mumol.kg-1.h-1 during fasting and decreased to 22.6 +/- 5 mumol.kg-1.h-1 (P < 0.05) on the carbohydrate diet. Precursor amino acid catabolism did not change significantly (22 +/- 5 vs 21.2 +/- 5 mumol.kg-1.h-1), suggesting that the 41% reduction in propionate production observed in response to feeding was related to the suppression of fatty acid oxidation. Therefore, significant therapeutic gains may be expected from the use of diets aimed at reducing lipid oxidation.

Adolescent↗

PubMed1994

The effect of Mycocurb, propionic acid, and calcium propionate on the intestinal strength of broiler chickens.

Field observations suggest that propionic acid-based mold inhibitors reduce the severity of proventriculitis and consequent fragile intestines. Therefore, two studies were conducted to determine the effects of a propionic acid-based mold inhibitor (Mycocurb), calcium propionate, and propionic acid on intestinal strength. Cobb x Cobb male broiler chicks were placed in an experimental design that consisted of six dietary treatments with four replicate floor pens of 40 (Experiment 1) and 30 (Experiment 2) broilers per pen. The dietary treatments in Experiment 1 consisted of control, 2.27, 4.54, and 9.07 kg/ton Mycocurb and 4.54 and 9.07 kg/ton calcium propionate. The dietary treatments in Experiment 2 consisted of control, 2.27, 4.54, and 9.07 kg/ton Mycocurb, and 4.54 and 9.07 kg/ton propionic acid. Water and the dietary treatments were made available to the broilers for ad libitum consumption from 1 d to 6 wk of age. In Experiment 1, five broilers from each pen were killed each week, a 10-cm section of intestine was removed anterior to the cecal junction, and its strength was measured. The contents of this section of intestine were collected and pH determinations were made on this material. In Experiment 2, five broilers were killed from each pen starting when the broilers were 3 wk of age, and every week thereafter a 10-cm section of intestine was removed posterior to the duodenal loop and its strength measured. The contents of this section of intestine were collected and pH determinations were performed on this material.(ABSTRACT TRUNCATED AT 250 WORDS)

Age Factors↗

PubMed1991

A double-blind, multicenter comparison of 0.05% halobetasol propionate ointment and 0.05% clobetasol propionate ointment in patients with chronic, localized plaque psoriasis.

In a double-blind, parallel-group, multicenter trial in 134 patients with severe, localized, plaque psoriasis, the success rate (described as "healed" or "marked improvement") at the end of the study was 96% in the halobetasol propionate group and 91% in the clobetasol propionate group. A significantly larger proportion of patients treated with halobetasol had no disease or mild disease after 14 days compared with those treated with clobetasol (86% versus 70%, p = 0.023). Healing within 24 days of starting treatment was noted in 69% and 56% of patients treated with halobetasol and clobetasol, respectively. Adverse effects were reported in a smaller percentage of patients treated with halobetasol propionate ointment than in those treated with clobetasol propionate ointment (7% versus 12%). Cosmetic acceptability and ease of application were recorded as "very good" in a larger percentage of patients treated with halobetasol propionate ointment than in the group treated with clobetasol propionate (90% versus 80%).

Adult↗

PubMed1998

Redox dependent changes at the heme propionates in cytochrome c oxidase from Paracoccus denitrificans: direct evidence from FTIR difference spectroscopy in combination with heme propionate 13C labeling.

Specific isotope labeling at the carboxyl groups of the four heme propionates of cytochrome c oxidase from Paracoccus denitrificans was used in order to assign signals observed in electrochemically induced redox Fourier transform infrared (FTIR) difference spectra of this enzyme. For this purpose, the hemA gene of the P. denitrificans strain PD1222, coding for 5-aminolevulinate synthase, was deleted by partial replacement with a kanamycin resistance cartridge, resulting in a stable 5-aminolevulinic acid (ALA) auxotrophy. Normal growth of this deficient strain and cytochrome c oxidase yield comparable to that of P. dentrificans wild-type strain PD1222 could be obtained by supplementation with 0.1 mM ALA in the growth medium. Visible spectra and reduced-minus-oxidized FTIR spectra showed that the purified cytochrome c oxidase had spectral characteristics identical to those of the wild-type enzyme. The decrease of a negative signal at 1676 cm-1 in the reduced-minus-oxidized FTIR difference spectra of the 13C-labeled cytochrome c oxidase in comparison to those of the unlabeled protein allowed the assignment of this signal to a COOH vibration mode of at least one of the four heme propionates. Moreover, a negative band at approximately 1570 cm-1 shifted to smaller wavenumbers in the spectra of the 13C-labeled enzyme in comparison to the spectra of the unlabeled enzyme and was thus assigned to contributions from an antisymmetric COO- mode of one or more of the four heme propionates. Additionally, a positive signal at 1538 cm-1 shifted to approximately 1500 cm-1 in the spectra of the isotopically labeled protein and was therefore assigned to at least one antisymmetric COO- mode of the heme propionates. A negative signal at 1390 cm-1, which has been shifted to 1360 cm-1 in the spectra of the 13C-labeled enzyme, is due to a symmetric COO- mode from at least one heme propionate. These results suggest that at least two of the four heme propionates in cytochrome c oxidase undergo significant vibrational changes upon reduction of the enzyme, either by protonation/deprotonation or by environmental changes.

5-Aminolevulinate Synthetase↗