- Email: [email protected]
A new isozyme of lactate dehydrogenase in the human placenta (?)
COMMUNICATIONS IN BRIEF
This section is suitable for reporting cases, results of therapeutic trials, and descriptions of new procedures or instruments. Reports should be limited to seven hundred words and two references. Use of an illustration or table requires a proportionate reduction in total words.
A new isozyme of lactate dehydrogenase in the human placenta (?) RUPI
PRASAD.
ANGEL
PH.D.
WERCH,
RAYMOND Department Mrdicine.
LDH
M.D. H.
KAUFMAN,
of Obstrtrzcs and Howton, Tmac
M.D. Gynrcolog?,
Baylor
College
of
LACTATE dehydrogenase (LDH) is a key enzyme in carbohydrate metabolism. It catalyzes the interconversion of lactate and pyruvate by simultaneous oxidation and reduction of the coenzyme NAD. This enzyme has been studied extensively in normal and neoplastic cells. Electrophoretically, at least five distinct isozymes of LDH can be separated. Each of these forms is a tetramer composed of four polypeptide subunits.‘, ’ These subunits are of two different kinds, usually referred to as A and B (or M and H). Subunits A and B are determined by separate gene loci.’ There is evidence for a third locus determining a distinctive subunit called C. which leads to the formation of LDH-X, a sperm-specific isozyme. A number of different genetically determined variants of LDH have been reported.3, ’ However, none of these so far discovered is significantly associated with any clinical abnormality. This report describes a different LDH isozyme found in human placental tissue. The isozyme is separated by starch-gel electrophoresis at pH 7.0 and is positioned between LDH-2 and LDH-3 (Fig. 1). We have studied placental samples from 63 women with normal pregnancies at term delivery. This isozyme was consistently present in all the samples. We speculate that this may be an LDH pro-
Reprint requests: rics
Texas
and
Gynecology,
Dr. Rupi Baylor
Prasad, College
Department of Medicine,
obcdefghijkl Fig. 1. Starch-gel electrophoretir genase from human placental
(u tol) pregnancy
human
pattern tissues (0.
of lactate dehydroorigin). Samples are
placentas from various women with normal
at term
delivery.
tein. determined by yet another separate gene locus. This may be potentially significant for clinical application. It would also be interesting to see if this new isozyme form is present in tumors such as trophoblast or choriocarcinoma. REFERENCES 1. Markert, C. L.: Lactate dehydrogenasc isozyme: Dissociation and recombination of subunits, Science 140: 1329, 1963. 2. Markert, C. L.: The molecular basis of isozymes, Ann. N. Y. Acad. Sci. 151: 14, 1968. 3. Bianco, A. Zinkham, W. H.. and Kypchyk, L.: Genetic control and ontogeny of lactate dehydrogenase in pigeon testes, J. Exp. 2001. 156: 137, 1964. 4. Zinkham, W. H.: Lactate dehydrogenase isozymes of testes and sperm: Biological and biochemical properties and genetic control, Ann. N. Y. Acad. Sci. 151: 598. 1968.
of ObstetHouston.
77030.
104
This section is suitable for reporting cases, results of therapeutic trials, and descriptions of new procedures or instruments. Reports should be limited to seven hundred words and two references. Use of an illustration or table requires a proportionate reduction in total words.
A new isozyme of lactate dehydrogenase in the human placenta (?) RUPI
PRASAD.
ANGEL
PH.D.
WERCH,
RAYMOND Department Mrdicine.
LDH
M.D. H.
KAUFMAN,
of Obstrtrzcs and Howton, Tmac
M.D. Gynrcolog?,
Baylor
College
of
LACTATE dehydrogenase (LDH) is a key enzyme in carbohydrate metabolism. It catalyzes the interconversion of lactate and pyruvate by simultaneous oxidation and reduction of the coenzyme NAD. This enzyme has been studied extensively in normal and neoplastic cells. Electrophoretically, at least five distinct isozymes of LDH can be separated. Each of these forms is a tetramer composed of four polypeptide subunits.‘, ’ These subunits are of two different kinds, usually referred to as A and B (or M and H). Subunits A and B are determined by separate gene loci.’ There is evidence for a third locus determining a distinctive subunit called C. which leads to the formation of LDH-X, a sperm-specific isozyme. A number of different genetically determined variants of LDH have been reported.3, ’ However, none of these so far discovered is significantly associated with any clinical abnormality. This report describes a different LDH isozyme found in human placental tissue. The isozyme is separated by starch-gel electrophoresis at pH 7.0 and is positioned between LDH-2 and LDH-3 (Fig. 1). We have studied placental samples from 63 women with normal pregnancies at term delivery. This isozyme was consistently present in all the samples. We speculate that this may be an LDH pro-
Reprint requests: rics
Texas
and
Gynecology,
Dr. Rupi Baylor
Prasad, College
Department of Medicine,
obcdefghijkl Fig. 1. Starch-gel electrophoretir genase from human placental
(u tol) pregnancy
human
pattern tissues (0.
of lactate dehydroorigin). Samples are
placentas from various women with normal
at term
delivery.
tein. determined by yet another separate gene locus. This may be potentially significant for clinical application. It would also be interesting to see if this new isozyme form is present in tumors such as trophoblast or choriocarcinoma. REFERENCES 1. Markert, C. L.: Lactate dehydrogenasc isozyme: Dissociation and recombination of subunits, Science 140: 1329, 1963. 2. Markert, C. L.: The molecular basis of isozymes, Ann. N. Y. Acad. Sci. 151: 14, 1968. 3. Bianco, A. Zinkham, W. H.. and Kypchyk, L.: Genetic control and ontogeny of lactate dehydrogenase in pigeon testes, J. Exp. 2001. 156: 137, 1964. 4. Zinkham, W. H.: Lactate dehydrogenase isozymes of testes and sperm: Biological and biochemical properties and genetic control, Ann. N. Y. Acad. Sci. 151: 598. 1968.
of ObstetHouston.
77030.
104