Gene/Protein
Disease
Symptom
Drug
Enzyme
Compound
Pivot Concepts:
Gene/Protein
Disease
Symptom
Drug
Enzyme
Compound
Target Concepts:
Gene/Protein
Disease
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Drug
Enzyme
Compound
Query: EC:3.1.3.5 (
5'-nucleotidase
)
3,167
document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)
In this study we report an overall procedure for the isolation of both human polymorphonuclear neutrophils and their plasma membrane, by means of self-generating Percoll gradients. After efficient purification (40% yield), neutrophils were lysed by nitrogen cavitation and cellular structures quickly isolated in a one-step procedure. Plasma membrane recovery was monitored by [3H]concanavalin A and
5'-nucleotidase
(
EC 3.1.3.5
) activity. We showed the latter activity is indeed present in human neutrophils. The procedure resulted in a good yield of plasma membrane, since 45% and 55% of total
5'-nucleotidase
and [3H]concanavalin A activity, respectively, were recovered within two gradient fractions. Depending on the final pH of the Percoll gradient medium, endoplasmic reticulum markers contaminated either the plasma membrane or the granule fractions. At pH 9.05, NADH-ferricyanide reductase activity clearly separated from plasma membrane markers and displayed the same profile as CDPcholine:diacylglycerolcholine phosphotransferase (
EC 2.7.8.2
), a typical enzyme of endoplasmic reticulum. These results emphasize the need for strict monitoring of the pH of the gradient medium in subcellular fractionation of neutrophils.
...
PMID:A rapid isolation procedure of plasma membranes from human neutrophils using self-generating Percoll gradients. Importance of pH in avoiding contamination by intracellular membranes. 299 31
The reversibility of phosphoethanolamine transferase (EC 2.7.8.1) in rat brain is demonstrated in this paper. Microsomal ethanolamine glycerophospholipids were prelabeled with an intracerebral injection of [3H]ethanolamine 4 h before killing young rats. Labeled CDPethanolamine was produced by incubation of the microsomes with CMP, although to a lesser extent than for the previously observed release of CDPcholine. Ethanolamine and choline glycerophospholipids were labeled with [2-3H]glycerol by incubation with primary cultures of rat brain. Microsomes from rat brains, with diisopropyl phosphofluoridate for inhibition of lipases, were incubated with the labeled glycerophospholipids separately, and labeled diacylglycerols were produced. The kinetic parameters of phosphoethanolamine transferase and phosphocholine transferase (
EC 2.7.8.2
) were compared by incubating rat brain microsomes with [3H]CMP. Inclusion of AMP in the reaction mixture was necessary in order to inhibit the hydrolysis of CMP by an enzyme with the properties of
5'-nucleotidase
(
EC 3.1.3.5
). For phosphoethanolamine transferase and phosphocholine transferase respectively, the Km values for CMP were 40 and 125 microM and the V values were 2.3 and 21.6 nmol/h per mg protein. The reversibility of both enzymes permits the interconversion of the diacylglycerol moieties of choline and ethanolamine glycerophospholipids. During brain ischemia, a principal pathway for degradation of ethanolamine glycerophospholipids may be by reversal of phosphoethanolamine transferase followed by hydrolysis of diacylglycerols by the lipase.
...
PMID:A comparison of the reversibility of phosphoethanolamine transferase and phosphocholine transferase in rat brain microsomes. 301 Nov 1
