[19-14C]androstenedione: A new substrate for assaying aromatase and studying its reaction mechanism

Douglas F. Covey; Patrick C. McMullan; Linda L. Wixler; Mayo Cabell

doi:10.1016/S0006-291X(88)80014-7

[19-¹⁴C]androstenedione: A new substrate for assaying aromatase and studying its reaction mechanism

Douglas F. Covey, Patrick C. McMullan, Linda L. Wixler, Mayo Cabell

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Abstract

[19-¹⁴C]Androstenedione has been prepared and utilized as a substrate for assaying microsomal human placental aromatase. Enzyme activity is determined by measuring the rate at which [¹⁴C]formate is produced by aromatization of this ¹⁴C-labeled steroid. Isotope ratio experiments using [19-¹⁴C]androstenedione and [1β-³H]androstenedione demonstrate that an apparent kinetic hydrogen isotope effect exists for the aromatization of the tritiated steroid with k_H/k_T ≈ 1.09. Metabolic switching occurs to a minor extent (≈3%) during aromatization of [1β-³H]androstenedione, but not during the aromatization of [19-¹⁴C]androstenedione.

Original language	English
Pages (from-to)	81-86
Number of pages	6
Journal	Biochemical and Biophysical Research Communications
Volume	157
Issue number	1
DOIs	https://doi.org/10.1016/S0006-291X(88)80014-7
State	Published - Nov 30 1988

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@article{4805d99fbb4948c9a6efe27809a3d772,

title = "[19-14C]androstenedione: A new substrate for assaying aromatase and studying its reaction mechanism",

abstract = "[19-14C]Androstenedione has been prepared and utilized as a substrate for assaying microsomal human placental aromatase. Enzyme activity is determined by measuring the rate at which [14C]formate is produced by aromatization of this 14C-labeled steroid. Isotope ratio experiments using [19-14C]androstenedione and [1β-3H]androstenedione demonstrate that an apparent kinetic hydrogen isotope effect exists for the aromatization of the tritiated steroid with kH/kT ≈ 1.09. Metabolic switching occurs to a minor extent (≈3%) during aromatization of [1β-3H]androstenedione, but not during the aromatization of [19-14C]androstenedione.",

author = "Covey, {Douglas F.} and McMullan, {Patrick C.} and Wixler, {Linda L.} and Mayo Cabell",

note = "Funding Information: We thank Dr. Paul Sherwin for helpful advice regarding the isotope ratio experiments and Dr. Daniel Canney for assistance in obtaining the 125 MHz 13C NMR spectra. This research was supported by NIH Grant CA 23582 (D.F.C.). Assistance was provided by the Washington Univ. High Resolution NMR Service Facility, supported in part by NIH 1 S10 RR00204 and a gift from the Monsanto Company.",

year = "1988",

month = nov,

day = "30",

doi = "10.1016/S0006-291X(88)80014-7",

language = "English",

volume = "157",

pages = "81--86",

journal = "Biochemical and Biophysical Research Communications",

issn = "0006-291X",

number = "1",

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TY - JOUR

T1 - [19-14C]androstenedione

T2 - A new substrate for assaying aromatase and studying its reaction mechanism

AU - Covey, Douglas F.

AU - McMullan, Patrick C.

AU - Wixler, Linda L.

AU - Cabell, Mayo

N1 - Funding Information: We thank Dr. Paul Sherwin for helpful advice regarding the isotope ratio experiments and Dr. Daniel Canney for assistance in obtaining the 125 MHz 13C NMR spectra. This research was supported by NIH Grant CA 23582 (D.F.C.). Assistance was provided by the Washington Univ. High Resolution NMR Service Facility, supported in part by NIH 1 S10 RR00204 and a gift from the Monsanto Company.

PY - 1988/11/30

Y1 - 1988/11/30

N2 - [19-14C]Androstenedione has been prepared and utilized as a substrate for assaying microsomal human placental aromatase. Enzyme activity is determined by measuring the rate at which [14C]formate is produced by aromatization of this 14C-labeled steroid. Isotope ratio experiments using [19-14C]androstenedione and [1β-3H]androstenedione demonstrate that an apparent kinetic hydrogen isotope effect exists for the aromatization of the tritiated steroid with kH/kT ≈ 1.09. Metabolic switching occurs to a minor extent (≈3%) during aromatization of [1β-3H]androstenedione, but not during the aromatization of [19-14C]androstenedione.

AB - [19-14C]Androstenedione has been prepared and utilized as a substrate for assaying microsomal human placental aromatase. Enzyme activity is determined by measuring the rate at which [14C]formate is produced by aromatization of this 14C-labeled steroid. Isotope ratio experiments using [19-14C]androstenedione and [1β-3H]androstenedione demonstrate that an apparent kinetic hydrogen isotope effect exists for the aromatization of the tritiated steroid with kH/kT ≈ 1.09. Metabolic switching occurs to a minor extent (≈3%) during aromatization of [1β-3H]androstenedione, but not during the aromatization of [19-14C]androstenedione.

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U2 - 10.1016/S0006-291X(88)80014-7

DO - 10.1016/S0006-291X(88)80014-7

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AN - SCOPUS:0024166625

SN - 0006-291X

VL - 157

SP - 81

EP - 86

JO - Biochemical and Biophysical Research Communications

JF - Biochemical and Biophysical Research Communications

IS - 1

ER -

[19-¹⁴C]androstenedione: A new substrate for assaying aromatase and studying its reaction mechanism

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