Selective release of plasma-membrane enzymes from rat hepatocytes by a phosphatidylinositol-specific phospholipase C

When isolated hepatocytes are incubated with phosphatidylinositol-specific phospholipase C, three cell-surface enzymes show markedly different behaviour. Most of the alkaline phosphatase is released at very low values of phosphatidylinositol hydrolysis, whereas further phosphatidylinositol hydrolysis releases only a maximum of about one-third of the 5'-nucleotidase. Alkaline phosphodiesterase I is not released. If cells containing phosphatidyl[3H]inositol are similarly treated, then the released [3H]inositol is in the form of inositol phosphate: no evidence has been obtained for any covalent association between released [3H]inositol and alkaline phosphatase.

Ecto-5'-nucleotidase activity in T and B lymphocytes from normal subjects and patients with congenital X-linked agammaglobulinemia

Ecto-5'-nucleotidase activity was measured in lymphocyte subpopulations isolated from normal subjects and patients with congenital X-linked agammaglobulinemia. B lymphocytes from normal subjects have at least three times more ecto-5'-nucleotidase activity than T lymphocytes. Patients with X-linked agammaglobulinemia have 56% of normal activity in their T cells, and lack a lymphocyte subpopulation high in nucleotidase activity. High activity of ecto-5'-nucleotidase may be a biochemical marker for mature surface immunoglobulin-bearing B cells.

High-performance liquid chromatographic assay for acid and alkaline phosphatase in serum

High-performance liquid chromatography was used to assay serum acid and alkaline phosphatase. Samples were incubated with adenosine-5'-monophosphoric acid (AMP) in a buffer of required pH, 5'-nucleotidase was inhibited with Ni2+ ions, and the phosphatase activity was determined by measuring the concentration of the reaction product, adenosine. The analysis time, after the incubation is terminated, is short (7 min), and the assay is quantitative and reproducible. Complete separation of the reaction product from the substrate and the naturally occurring serum constituents and the high sensitivity of the ultraviolet detection system eliminate some of the problems commonly encountered in spectrophotometric assays.

5'-Nucleotidase activity in subpopulations of rat lymphocytes

Rat lymphocyte populations were assessed for 5'-nucleotidase activity by both biochemical and histochemical methods. Enzyme-specific activity was enriched in lymphocyte plasma membrane fractions and was higher in lymph node and spleen lymphocytes than in thymocytes. Histochemical reactions on sections of spleen and lymph node revealed strong activity in the thymus-dependent regions, periarteriolar lymphoid sheath in spleen, and paracortex in lymph node; whereas the thymus-independent regions, follicles, and germinal centers were negative. In cellular depletion experiments, with three different methods to detect 5'-nucleotidase, it was observed that the depletion of T cells, but not B cells, was accompanied by a loss of enzyme activity and a decrease in the percentage of nucleotidase-positive cells. The results suggest that, among members of the lymphocyte series, high 5'-nucleotidase activity is selectively associated with the plasma membranes of peripheral T cells in the rat.

Serum enzyme tests in diseases of the liver and biliary tree

Eight serum enzyme tests were performed over a three-year period in 1,147 cases of patients with suspected hepatobiliary disease, of whom 580 had identifiable primary disease of the liver or biliary system. Individually, aminotransferase assays did not provide good discrimination among the various categories of hepatobiliary disease, but when expressed as a ratio a useful degree of discrimination was obtained. Isocitrate dehydrogenase, guanase and glutamate dehydrogenase alone were poor discriminants of the various disease categories studied; combination of the latter enzyme with the aminotransferases in various ratios did not achieve worthwhile improvement. Adenosine deaminase was normal in most patients with extrahepatic obstruction and abnormal in most patients with parenchymal hepatic disease, and is potentially a useful test additional to the aminotransferases in routine diagnosis. 5'-Nucleotidase was more sensitive and specific than alkaline phosphatase in diagnosing hepatobiliary disorders. Abnormalities of all these enzymes were encountered in patients who did not have hepatobiliary disease, most frequently among subjects with cancer, diabetes mellitus, and diseases of the respiratory and cardiovascular systems.

Biochemical and functional characteristics of the plasma membrane of macrophages from BCG-infected mice

A set of quantitative signs of activation, previously developed in studies of inflammatory peritoneal macrophages, has been applied to the study of immunologically stimulated peritoneal cells. Mice that are infected systemically with Bacillus Calmette Guérin (BCG) and then challenged locally with soluble mycobacterial antigens generate populations of cells that spread rapidly in culture, display an elevated pinocytic rate, ingest IgMC-coated sheep erythrocytes, and have diminished levels of 5'-nucleotidase activity. These effects depend on sensitization with live organisms, require secondary antigenic challenge, and develop on the same schedule as does effective cell-mediated immunity. The challenge is antigen specific and cannot be replaced by a nonspecific inflammatory stimulus. Thus, the characteristics of inflammatory macrophages that were previously defined are applicable to the study of immunologically mediated macrophage activation. Cells sharing this pattern of characteristics, whatever their mode of generation, are proposed to represent a distinct class of differentiated macrophages, as compared with the resident macrophage population.

Specific release of plasma membrane enzymes by a phosphatidylinositol-specific phospholipase C

The release of plasma membrane ecto-enzymes by a phosphatidylinositol-specific phospholipase C from Staphylococcus aureus was investigated. There was no effect on L-leucyl-beta-naphthylamidase, alkaline phosphodeisterase I and Ca2+- or MG2+-ATPase, but substantial proportions of the alkaline phosphatase and 5-nucleotidase were released. There was no simultaneous release of phospholipid and the solubilized enzymes were not exluded from Sepharose 6-B. It was therefore concluded that release was not a secondary consequence of membrane vesiculation but occurred as a result of the disruption of specific interactions involving the phosphatidylinositol molecule.

On the structure of the prosthetic group of citrate (pro-3S)-lyase

The prosthetic group of citrate (pro-3S)-lyase from Klebsiella aerogenes as well as Streptococcus diacetilactis was obtained eigher by beta elimination or pronase digestion of the enzyme and purified by DEAE-cellulose chromatography. The compound was shown to contain 3 mol of PO4, 2 mol of ribose, and 1 mol of sulfhydryl/mol of adenine. 5'-AMP and dephospho-CoA are components of the prosthetic group. The evidence obtained so far support our proposed structure of 3' (or 2') leads to 1''-(5''-phosphoribosyl)dephospho-CoA for the prosthetic group of citrate lyase. The presence of one phosphomonoester group in the compound isolated after beta elimination and the absence of the same in the compound isolated after pronase digestion indicated that the prosthetic group is attached to the enzyme through a phosphodiester bond. Analyses of the pyruvate released by beta elimination and subsequent acid hydrolysis of the peptide-bound prosthetic group and its degradation products showed that the phosphodiester linkage is between the hydroxyl group of a serine residue of the protein and the 5''-PO4 group of the second ribose.

Isolation and characterization of N6-succinyladenosine from human urine

From the urines of colon carcinoma patients and normal subjects we have isolated a nucleoside in which an amino group of aspartic acid is attached to the six position of purine ribonucleoside. The structure, N6-succinyladenosine, N-(9-B-D-ribofuranosylpurin-6-yl)aspartic acid was assigned on the basis of spectral data, chemical degradation, and by synthesis. The ultraviolet and mass spectra, chromatographic and electrophoretic mobilities, and the chemical properties of the naturally occurring nucleoside were identical to those of the synthetic N6-succinyladenosine. In contrast to the methylated and hypermodified nucleosides which are products of RNA catabolism, this urinary nucleoside appears to be derived from adenylosuccinic acid, a key intermediate required in the biosynthesis of ubiquitous, natural purine nucleotide adenosine-5'-monophosphate (AMP).

Plasma-membrane components can be removed from isolated lymphocytes by the bile salts glycocholate and taurocholate without cell lysis

Glycocholate and taurocholate removed from isolated pig lymphocytes a proportion of the cells' complement of 5'-nucleotidase, alkaline phosphatase and alkaline phosphodiesterase I before cell lysis. This may indicate a loss of externally orientated plasma-membrane components.

Ribonucleoside 3'-di- and -triphosphates. Synthesis of guanosine tetraphosphate (ppGpp)

A procedure has been outlined for the synthesis of ribonucleoside 3'-di- and -triphosphates. The synthetic scheme involves the conversion of a ribonucleoside 3'-monophosphate to its 2'-(5'-di)-O-(1-methoxyethyl) derivative, followed by successive treatments of the blocked ribonucleotide with 1,1'-carbonyldiimidazole and mono(tri-n-butylammonium) phosphate or pyrophosphate. The resulting ribonucleoside 3'-di- and -triphosphate derivatives are then deblocked by treatment with dilute aqueous acetic acid, pH 3.0. The use of this procedure is illustrated for adenosine 3'-monophosphate, which has been converted to its corresponding 3'-di- and -triphosphates in 61% overall yield. The decomposition of adenosine 3'-di- and -triphosphates to adenosine 2'-monophosphate, adenosine 3'-monophosphate, and adenosine cyclic 2',3'-monophosphate as a function of pH at 100 degrees has been studied as has the attempted polymerization of adenosine 3'-diphosphate with polynucleotide phosphorylase. Also prepared was guanosine 5'-diphosphate 3'-diphosphate (guanosine tetraphosphate; ppGpp), which was accessible via treatment of 2'-O-(1-methoxyethyl)guanosine 5'-monophosphate 3'-monophosphate with the phosphorimidazolidate of mono(tri-n-butyl ammonium) phosphate. The resulting blocked tetraphosphate was deblocked in dilute aqueous acetic acid to afford ppGpp in an overall yield of 18%.