The kinetic properties of human placental choline acetyltransferase
نویسندگان
چکیده
منابع مشابه
Human brain and placental choline acetyltransferase: purification and properties.
Choline acetyltransferase (EC 2.3.1.6) catalyzes the biosynthesis of acetylcholine according to the following chemical equation: acetyl-CoA + choline in equilibrium to acetylcholine + CoA. In addition to nervous tissue, primate placenta is the only other animal source which contains appreciable acetylcholine and its biosynthetic enzyme. Human brain caudate nucleus and human placental choline ac...
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The rapid and sensitive assay of lfl,2@3H-androgen aromatization by measurement of ‘HZ0 release (Thompson, E. A., Jr., and Siiteri, P. K. (1974) J. Biol. Chem. 249,5364-5372) has been analyzed to determine its applicability to initial rate studies. It was found that aromatization is the sole reaction catalyzed by lyophilized placental microsomes that causes a loss of tritium from position 1 or ...
متن کاملEffect of environmental temperature on the kinetic properties of goldfish brain choline acetyltransferase.
1. Michaelis constants of goldfish brain choline acetyltransferase were found to depend on the concentration of the second substrate present and on the temperature to which the fish had been adapted. 2. Primary plots constructed from results obtained with enzyme prepared from cold-adapted or warm-adapted fish indicated that synthesis of acetylcholine took place by a sequential mechanism. 3. The...
متن کاملThe choline acetyltransferase of human placenta.
1. Various methods for the extraction of choline acetyltransferase (acetyl-CoA-choline O-acetyltransferase, EC 2.3.1.6) from immature human placenta (18-28 weeks of gestation) are described. 2. The crude enzyme was found to be stable at -18 degrees and +4 degrees under a variety of conditions. 3. Purification methods, including ammonium sulphate fractionation, gel filtration on various grades o...
متن کاملHuman placental cytoplasmic 5'-nucleotidase. Kinetic properties and inhibition.
The kinetic properties of highly purified human placental cytoplasmic 5'-nucleotidase were investigated. Initial velocity studies gave Michaelis constants for AMP, IMP, and CMP of 18, 30, and 2.2 microM, respectively. The enzyme shows the following relative Vmax values: CMP greater than UMP greater than dUMP greater than GMP greater than AMP greater than dCMP greater than IMP. The activity was ...
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ژورنال
عنوان ژورنال: Biochemical Journal
سال: 1971
ISSN: 0306-3283
DOI: 10.1042/bj1250857