Oxygen Isotope Fractionation in Reactions Catalyzed by Enzymes

Feldman, Daniel E.; Yost, Henry T.; Benson, Bruce B.

doi:10.1126/science.129.3342.146

Cited by 28 publications

(10 citation statements)

References 8 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…10 -2 6a). These results show considerably higher fractionation effects than reported by Feldman et al [3] for the pure oxydation of cytochrome oxidase and tyrosinase enzyme systems, where fractionation values of 1.010 to 1.013 have been reported. As these enzymes are widespread in living systems and the corresponding reactions prevalent in aerobic organisms the results indicate that still other fractionation processes occur in living systems.…”

Section: Resultscontrasting

confidence: 76%

“…They found fractionation factors in the range of c~ = 1.007 to ce = 1.025 [2]. In response to these results measurements of the oxygen isotope fractionation in reactions catalyzed by enzymes have been performed in order to elucidate the contribution of enzymes to the overall fractionation [3]. These experiments revealed values in the range of o~ = 1.010 to cr = 1.013, which indicates, that fractionation processes other than those reported may occur in living systems.…”

Section: Introductionmentioning

confidence: 96%

See 1 more Smart Citation

Oxygen isotope fractionation during respiration for different temperatures ofT. utilis andE. coli K12

Schleser

1979

Radiat Environ Biophys

View full text Add to dashboard Cite

The temperature dependence of the oxygen isotope fractionation factor during respiration has been examined for two different microorganisms, namely Torulopsis utilis and Escherichia coli K12 representing a yeast and a bacterium, respectively. The investigation covered a temperature range of 18 degrees C, that is from 16 degrees C to 34 degrees C for T. utilis and from 19 degrees C to 37 degrees C for E. coli K12. Within this temperature range the fractionation factor of T. utilis increases by 0.18% an insignificant change (delta delta 10 degrees C = 0.063%; r = 0.067), whereas with E. coli K12 an increase of 1.12% has been observed (delta delta 10 degrees C = 0.6%; r = 0.55).

show abstract

Section: Resultscontrasting

confidence: 76%

Section: Introductionmentioning

confidence: 96%

Oxygen isotope fractionation during respiration for different temperatures ofT. utilis andE. coli K12

Schleser

1979

Radiat Environ Biophys

View full text Add to dashboard Cite

show abstract

“…It is likely that the oxygen isotopic fractionation results from more than one mechanism. First, as demonstrated by Feldman et al (1959), fractionation can occur during cellular respiration, probably as a result of metalloenzymes. Secondly, transport processes involving gaseous diffusion or diffusion across membranes (i.e.…”

Section: Discussionmentioning

confidence: 99%

Effect of increased metabolic rate on oxygen isotopic fractionation

Zanconato

Cooper

Armon

et al. 1992

Respiration Physiology

View full text Add to dashboard Cite

16O16O is preferentially used over 18O16O (a stable isotope of oxygen comprising about 0.2% of atmospheric O2) as oxygen is consumed during respiration in humans (Epstein and Zeiri, 1988, Proc. Natl. Acad. Sci. USA 85: 1727-1731). To test the hypothesis that oxygen isotopic fractionation is related to the metabolic rate, 8 healthy adults performed 5 min of constant work rate cycle ergometer exercise below and above their anaerobic threshold. Moreover, 3 subjects performed an incremental exercise to the limit of tolerance. Oxygen uptake (VO2) was measured breath by breath. Samples of the exhaled breath for oxygen isotope measurement were obtained at rest and at various times during exercise and recovery. Oxygen isotopic fractionation was determined by isotope ratio mass spectrometry and calculated as the ratio of the degree of fractionation to the oxygen consumed in the breath sample (Z value). For the constant work rate protocol, both low and high intensity exercise resulted in a significant decrease in Z compared to the rest values (P less than 0.01). However, for the high intensity exercise the reduction in fractionation was greater compared to the low intensity protocol (P less than 0.05). For the incremental test, there was a significant negative correlation between oxygen isotopic fractionation and VO2 expressed as percent of the maximal oxygen uptake (r = -0.91, P less than 0.0001). These data suggest that during exercise low-fractionating processes become more important as limiting steps for O2 transport.

show abstract

“…Fractionation effect of O2-diffusion amounts to 30%0, provided that ~(1602)//~(160180 ) is extrapolated to body temperature of 310 K. Feldman et al [3] found for reactions of the respiratory chain that 1602 is metabolized 13%o more rapidly than 160180. The fractionation effect of Oe-utilization therefore comes to 139'oo.…”

Section: Introductionmentioning

confidence: 97%

Dependence of overall fractionation effect of respiration on ventilation at rest

Heller

Könen

Schuster

1993

Isotopenpraxis Isotopes in Environmental and Health Studies

View full text Add to dashboard Cite

The influence of ventilation on overall fractionation effect of respiration (6~u) between the stable isotopic oxygen molecules 1602 and ~60180 is investigated by experiments performed on 6 healthy humans breathing air at rest.The ~$1u-values increase with rising ventilatory rate in terms of a linear relationship of 6~u-values to alveolar partial pressure of oxygen PAO2" The slope of that increase is calculated to be 0.078%0 per 1 mmHg of increase in PAOZWith the aid of a model of respiration, it is concluded that overall fractionation effect of respiration can be split into the contributing fractionating and non-fractionating processes.

show abstract

Oxygen Isotope Fractionation in Reactions Catalyzed by Enzymes

Abstract: A study has been made of some of the enzymatic mechanisms responsible for the previously reported fractionation of oxygen isotopes by whole organisms. The data indicate that the fractionation occurs through the activity of metalloenzymes.

Cited by 28 publications

References 8 publications

Oxygen isotope fractionation during respiration for different temperatures ofT. utilis andE. coli K12

Oxygen isotope fractionation during respiration for different temperatures ofT. utilis andE. coli K12

Effect of increased metabolic rate on oxygen isotopic fractionation

Dependence of overall fractionation effect of respiration on ventilation at rest

Contact Info

Product

Resources

About