Partial characterization of a novel endogenous opioid in human cerebrospinal fluid

Human cerebrospinal fluid (CSF) contains many uncharacterized endogenous opioids, in addition to the known enkephalins, endorphins, and dynorphins. These opioids may be separated by gel filtration chromatography and identified by radioreceptor assay for opioid activity. One region of the chromatographic elution profile, designated "Peak B" has previously been shown to be related to the pain status of chronic pain patients. We now report that human Peak B isolated from the CSF of pain-free elective surgery patients is present at a typical concentration equivalent in activity to 1.4 pmol of morphine sulfate per ml of CSF measured by radioreceptor assay. At a dose of 0.06 and 0.12 pmol morphine sulfate equivalents of CSF (MSE), injected into the cerebroventricular system of the mouse, Peak B produced an antinociceptive effect, the intensity and duration of which was dose-dependent and which was antagonized by naloxone. The mouse vas deferens (MVD) preparation was inhibited by Peak B in a manner that was sensitive to antagonism by naloxone only at low (less than 1.0 microM) but not at higher (greater than 6.0 microM) concentrations of the antagonist. Peak B activity in the MVD assay was unaffected by treatment with trypsin or alpha-chymotrypsin.     

Interaction mechanisms of imipramine and desipramine with enkephalin-degrading aminopeptidases in vitro

In the last few years, considerable evidence has appeared concerning the importance of the opioid systems in the action mechanism of some antidepressant drugs. This action mechanism could be mediated through the inhibition of the enzymes reponsible for enkephalin degradation. In this sense, imipramine treatment in vivo increases the enkephalin levels, and this effect is enhanced by inhibitors of enkephalin-degrading enzymes. The present work shows the effects in vitro of imipramine and its active metabolite desipramine on the activities of two membrane-bound enkephalin-degrading aminopeptidases present in rat brain. Imipramine and desipramine in vitro do not affect the aminopeptidase M activity, but they reversibly inhibits the aminoeptidase MII. The enzyme kinetic analysis shows that this enzyme molecule has two different binding sites for each drug, which exert a mixed type enzyme inhibition.     

Partial purification of somatomedin from human plasma.

Fractional precipitation of human plasma using ethanol, followed by chromatography on S.P. Sephadex, yielded a somatomedin-enriched fraction freed from substantial amounts of inhibitory substances. Heat coagulation of the proteins present in this fraction allowed the recovery of appreciable amounts of active components which were then chromatographed on Sephadex G-75 and S.P. Sephadex. A major part of the activity was associated with components less than 4,000 daltons, suggesting that somatomedin, or an active fragment thereof, had been dissociated from a carrier protein by the heat treatment. The range of pH employed throughout was 5.3-9.8. Recoveries of about 30% of biological activity with fold-purification up to 38, as measured by radioactive sulphate uptake in the chick pelvic cartilage assay, were higher than those obtained using acid-ethanol extraction.     

Isolation,purification and partial characterisation of prealbumin from cerebrospinal fluid

Prealbumin from human cerebrospinal fluid was purified using a combination of ammonium sulphate precipitation, phenol precipitation, Polyacrylamide disc gel electrophoresis and gel filtration on Sephadex G-100. The homogeneity of the purified protein was established by Polyacrylamide gel electrophoresis and Immunoelectrophoresis. On the basis of its molecular weight (55,000), amino acid composition, electrophoretic mobility and immunological cross-reactivity, the prealbumin from cerebrospinal fluid showed complete identity with serum prealbumin. The cerebrospinal fluid prealbumin levels in various neurological disorders may have a diagnostic significance. Part of the Ph. D. thesis submitted by the first author.     

Peptidases from pig reproductive tract: purification and properties of aminopeptidases from uterine secretions, allantoic fluid, and amniotic fluid

In ovariectomized sows, aminopeptidase is secreted into the uterine lumen under the influence of progesterone. The enzyme also accumulates in allantoic and amniotic fluids of pregnant animals. We have purified the predominant form of this enzyme from uterine flushings, allantoic fluid, and amniotic fluid by the following steps: ammonium sulfate precipitation, Sepharose 6B chromatography, ion-exhange chromatography on diethylaminoethyl cellulose, and affinity chromatography usingl-leucylglycine immobilized on agarose. The overall procedure gave approximately 974-, 110-, and 230-fold purifications of the allantoic, uterine, and amniotic enzymes, respectively. The enzymes from all three sources are glycoproteins with pI's around 4 and molecular weights of about 480,000. They may be dissociated into six apparently identical subunits of molecular weight 80,000 as judged by sodium dodecyl sulfate gel electrophoresis. With l-leucyl-β-naphthylamide as substrate the pH optimum and apparent K_m value for each enzyme were 7.1 and 14 μm, respectively. However, the uterine and allantoic aminopeptidases exhibited V values of 0.35 μmol of substrate hydrolyzed/min/mg of protein, whereas the V for the amniotic enzyme was at least sixfold greater. The amniotic enzyme also differed from the other two in pH and temperature stability. The activity of all three enzymes was stimulated by Co²⁺ and inhibited by Cu²⁺, Fe³⁺, and chelating agents, while iodoacetate and mercaptoethanol had no effect on catalysis. The effect of Co²⁺ on the allantoic enzyme was investigated in further detail. The stimulation of peptidase activity by Co²⁺ was shown to be a complex process but consistent with Co²⁺ replacing another metal at the active site and at some other additional site on the enzyme. The function of the aminopeptidases in the pregnant uterus is unknown.     

A bromine compound isolated from human cerebrospinal fluid

A new bromine compound with properties characteristic of a ketone was isolated from human cerebrospinal fluid. It was degraded by alkali treatment producting acetic acid, glycoli acid, oxalic acid, HBr and 1-methylheptanol. By this treatment, a part of the compound was converted to di-1-methylheptyl-2,5-dioxocyclohexane-1,4-dicarboxylate. These degradation products were also obtained from synthetic 1-methylheptyl-γ-bromoacetoacetate by alkali treatment. 1-methylheptyl-γ-bromoacetoacetate and realted substances were synthesized and compared with the isolated bromine compound in chemical properties, infrared spectra, spectra of nuclear magnetic resonance, and elemental analysis, etc. These results showed that the isolated bromine compound corresponded well to 1-methylheptyl-γ-bromoacetoacetate (synonym of 2-octyl-γ-bromoacetoacetate).     

Partial purification of androgen receptor from hypertrophic human prostate

For purification of androgen receptor from hypertrophic human prostate, solutions used for elution of androgen receptor from DNA Sepharose, affinity labeling of the receptor and ability of affinity gel to retain the receptor were examined. Elution with 20 mM pyridoxal 5'-phosphate of the receptor from DNA Sepharose was more efficient than that with diluted pyridoxal 5'-phosphate, high ionic solution or various concentrations of Mg++, 3H-dihydrotestosterone bromoacetate was applicable to covalent binding with partially purified androgen receptor regardless of the low specificity of the ligand. Affinity gel of thiopropyl-Sepharose 6B coupled to 17 alpha-(2', 3'-epoxy-propyl)-5 alpha-dihydrotestosterone was better than Affigel 102 coupled to N-[3-(3-oxo-5 alpha-androstane-17 beta-yloxycarbonyl) propionyloxy] succimide or aminoethyl-Sepharose 4B coupled to 17 alpha-carboxyethynyl testosterone with respect to the rate of retention of androgen receptor. In view of these observations, the following purification procedures were constructed: Removal of DNA Sepharose-binders from the cytosol, 40% ammonium sulfate precipitation, affinity chromatography using thiopropyl-Sepharose 6B coupled to 17 alpha-(2',3'-epoxypropyl)-5 alpha-dihydrotestosterone, and DNA Sepharose chromatography. After affinity labeling of the receptor thus obtained, the molecular weight was estimated. Some 1300-fold purification with a yield of 0.25% of the androgen receptor was achieved. The molecular weight of the receptor was mainly 45 K with 90 K in a lesser amount. The Stokes radius was calculated as 30 A.     

Partial purification of an antimitogenic factor from human semen

This communication reports the partial purification of a factor (called semen lymphocyte inhibitory factor, SLIF, and it is probably a peptide), which possesses inhibitory activity on PHA-induced lymphocyte transformation.     

The specificity in vivo of two distinct methionine aminopeptidases in Saccharomyces cerevisiae.

In Saccharomyces cerevisiae, the essential function of amino-terminal methionine removal is provided cotranslationally by two methionine aminopeptidases (MetAP1 and MetAP2). To examine the individual processing efficiency of each MetAP in vivo, we measured the degree of N-terminal methionine cleavage from a series of mutated glutathione-S-transferase (GST) proteins isolated from yeast wild-type, a map1 deletion strain, a map2 deletion strain, and a map1 deletion strain overexpressing the MAP2 gene. We found that MetAP1 plays the major role in N-terminal methionine removal in yeast. Both MetAPs were less efficient when the second residue was Val, and MetAP2 was less efficient than MetAP1 when the second residue was Gly, Cys, or Thr. These findings indicate that MetAP1 and MetAP2 exhibit different cleavage efficiencies against the same substrates in vivo. Interestingly, although methionine is considered a stabilizing N-terminal residue, we found that retention of the initiator methionine on the Met-Ala-GST mutant protein drastically reduced its half-life in vivo.     

Partial purification and characterization of two Peptide hydrolases from pea seeds

Two peptide hydrolases have been found in pea seeds (Pisum sativum var. Greenfeast) and extensively purified by ion exchange chromatography using benzoyl-dl-arginine-p-nitroanilide as substrate. The enzymes which both have molecular weights of 65,000 can be separated by anion exchange chromatography but are otherwise virtually identical in the properties tested. They did not hydrolyze several common protease substrates but readily hydrolyzed small peptides containing basic amino acids on the carboxyl side of these residues. They are completely inhibited by diisopropylfluorophosphate and are inhibited to varying extents by thiol reagents.     

The human cerebrospinal fluid metabolome

With continuing improvements in analytical technology and an increased interest in comprehensive metabolic profiling of biofluids and tissues, there is a growing need to develop comprehensive reference resources for certain clinically important biofluids, such as blood, urine and cerebrospinal fluid (CSF). As part of our effort to systematically characterize the human metabolome we have chosen to characterize CSF as the first biofluid to be intensively scrutinized. In doing so, we combined comprehensive NMR, gas chromatography-mass spectrometry (GC-MS) and liquid chromatography (LC) Fourier transform-mass spectrometry (FTMS) methods with computer-aided literature mining to identify and quantify essentially all of the metabolites that can be commonly detected (with today's technology) in the human CSF metabolome. Tables containing the compounds, concentrations, spectra, protocols and links to disease associations that we have found for the human CSF metabolome are freely available at http://www.csfmetabolome.ca.     

Neuropeptides in human cerebrospinal fluid

Ten neuropeptides were measured by RIA in human cerebrospinal fluid obtained from 30 normal volunteers. The levels of seven peptides (corticotropin releasing factor, adrenocorticotropin, vasoactive intestinal peptide, somatostatin, beta-endorphin, beta-lipotropin, and the N-terminal fragment of proopiomelanocortin) were highly, positively correlated with one another. This result is consistent with the hypothesis that cerebrospinal fluid levels of these seven peptides are a function of some common regulatory factor, such as shared release into the cerebrospinal fluid.     

Endorphins in human cerebrospinal fluid

Opiate activity in CSF samples drawn from patients with suspected intracranial hydrodynamic dysfunction has been fractionated on Sephadex G-10 and separated by column electrophoresis in agarose suspension. From the Sephadex G-10 chromatography two receptor active fractions (FI and FII) were recovered. Both FI and FII were further resolved by the electrophoresis. FI separated into at least four components and FII into two components. The study also includes a comparison of the endorphin concentrations in CSF (samples drawn from healthy volunteers) measured by receptorassay with those detected by radioimmunoassay of beta-endorphin, [Met]enkephalin and dynorphin, respectively. The data obtained indicated negligible quantities of the radioimmunoassayable endorphins in the total CSF opiate activity.     

Partial purification and characterization of phosphatidylinositol kinases from human platelets

Most of human platelet phosphatidylinositol (PI) kinase activity (approx. 80%) was associated with the membrane fraction and its majority was released by the extraction with Triton X-100 after KCl treatment. Two major activity peaks (mPIK-I and mPIK-III) were obtained by Mono Q column chromatography. They were distinct from each other with regard to Mr (76,000 and 80,000 as determined by gel-filtration chromatography), apparent Km values for ATP, effect of arachidonic acid and phosphatidylserine and detergent requirement. Triton X-100 inhibited the activity of mPIK-I but rather weakly enhanced the mPIK-III activity, and sodium cholate remarkably inhibited both mPIK-I and mPIK-III activities. Their products were identified to be phosphatidylinositol 4-phosphate. On the other hand, about 20% of PI kinase activity was recovered from the cytosolic fraction and two activity peaks (cPIK-I and cPIK-II) were resolved on Mono Q column chromatography. There were no significant differences in biochemical properties between cPIK-I and cPIK-II. Both of them had Mr approx. 550,000 as determined by gel-filtration chromatography and were activated by sodium cholate to a greater extent than by Triton X-100. The results suggest that the major PI kinases (mPIK-I and mPIK-III) are PI 4-kinase and mPIK-I is distinct from PI 4-kinases in other sources especially with regard to the effect of Triton X-100.     

Partial purification and characterization of gamma-secretase from post-mortem human brain

One characteristic feature of Alzheimer's disease is the deposition of amyloid beta-peptide (Abeta) as amyloid plaques within specific regions of the human brain. Abeta is derived from the amyloid beta-peptide precursor protein (beta-APP) by the intramembranous cleavage activity of gamma-secretase. Studies in cells have revealed that gamma-secretase is a large multimeric membrane-bound protein complex that is functionally dependent on several proteins, including presenilin, nicastrin, Aph-1, and Pen-2. However, the precise biochemical and molecular nature of gamma-secretase is as yet to be fully elucidated, and no investigations have analyzed gamma-secretase in human brain. To address this we have developed a novel in vitro gamma-secretase activity assay using detergent-solubilized cell membranes and a beta-APP-derived fluorescent probe. We report that human brain-derived gamma-secretase activity co-purifies with a high molecular weight protein complex comprising presenilin, nicastrin, Aph-1, and Pen-2. The inhibitor profile and solubility characteristics of brain-derived gamma-secretase are similar to those described in cells, and proteolysis occurs at the Abeta40- and Abeta42-generating cleavage sites. The ability to isolate gamma-secretase from post-mortem human brain may facilitate the identification of brain-specific modulators of beta-APP processing and provide new insights into the biology of this important factor in the pathogenesis of Alzheimer's disease.     

Partial purification and characterization of a recombinase from human cells

We describe the partial purification and characterization of a human recombinase activity from RPMI 1788 B lymphoblasts. Stoichiometric amounts of recombinase carry out a strand transfer reaction between linear duplex DNA and homologous circular single-strand DNA. The product of strand transfer by the recombinase is a joint molecule composed of a single-strand circle joined to one end of the linear duplex molecule by a region of DNA heteroduplex at least 150 bp long. Formation of DNA heteroduplexes is accompanied by strand displacement. Strand invasion initiates at the ends of the linear duplex. Finally, strand displacement by human recombinase exhibits polarity and proceeds in a 3' to 5' direction. This is the first demonstration of a strand transfer activity from a high eukaryote. We discuss similarities between our recombinase and the RecA and rec1 recombination proteins from E. coli and Ustilago maydis, respectively.