Localization of carbonic anhydrase in the rat lung

Summary The localization of carbonic anhydrase in the rat lung has been demonstrated, at light and electron microscopic levels, by the cobalt bicarbonate histochemical method of Hansson. Focal deposits of the cobalt sulfide reaction product were found not only in the capillary endothelium of the alveolar walls, but also in the small and large alveolar cells. The histochemical reaction was abolished by two potent inhibitors, acetazolamide (10^–5 to 10^–6 M) and KCNO (5×10^–3 to 10×10^–3 M). Physiological assay with Maren's method indicated that values for carbonic anhydrase activity in rat lung are 4.4±0.8 UA/mg of protein, 25.0±5.5 UA/mg of nitrogen, and 369±86 UA/g of wet weight. In addition, it was calculated that after fixation in glutaraldehyde-formaldehyde-picric acid about 9% activity is retained.     

Selective inhibition of thrombin by (2R,4R)-4-methyl-1-[N2-[(3-methyl-1,2,3,4-tetrahydro-8-quinolinyl++ +) sulfonyl]-l-arginyl)]-2-piperidinecarboxylic acid

The potency of thrombin inhibition by 4-methyl-1-[N2-[(3-methyl-1,2,3,4-tetrahydro-8-quinolinyl)-sulfony l]- L-arginyl]-2-piperidinecarboxylic acid (MQPA) depended on the stereoconformation of the 2-piperidinecarboxylic acid moiety. Ki values for bovine alpha-thrombin were 0.019 microM with (2R,4R)-MQPA, 0.24 microM with (2R,4S)-MQPA, 1.9 microM with (2S,4R)-MQPA, and 280 microM with (2S,4S)-MQPA. (2R,4R)-MQPA of the four stereoisomers of MQPA was also the most potent inhibitor for other trypsin-like serine proteases with Ki values of 5.0 microM for trypsin, 210 microM for factor Xa, 800 microM for plasmin, and 1500 microM for plasma kallikrein. Examination of the potency of thrombin inhibition by arginine derivatives related to MQPA in structure suggested the presence of a specific binding site for the carboxamide portion (C-terminal side). The relative inhibitory potency of the four stereoisomers of MQPA for trypsin was nearly identical with that for thrombin, suggesting that the specific binding site for the carboxamide portion is present in both enzymes. Modification of thrombin by phosphopyridoxylation or the presence of heparin did not significantly alter the binding of MQPA.     

p-nitrophenyl butyrate hydrolyzing activity of hormone-sensitive lipase from bovine adipose tissue

The "esterase" activity of hormone-sensitive lipase (HSL) was studied using water-soluble p-nitrophenyl butyrate (PNPB) as a substrate. Bovine adipose tissue HSL was purified to near homogeneity by precipitation at pH 5.0, followed by chromatography on DEAE-cellulose, phenyl-Sepharose, and high performance ion-exchange columns on Mono Q and Mono S. The purified preparation hydrolyzed emulsified triolein and cholesteryl oleate (CO), and water-soluble PNPB. In the two last steps of purification, the elution profile of the CO-hydrolyzing activity coincided with that of PNPB-hydrolyzing activity. The HSL was adsorbed to heparin-Sepharose and the CO- and PNPB-hydrolyzing activities were eluted together in the same peak. Diisopropylfluorophosphate (DFP) strongly inhibited the HSL activities and the inhibition profiles of the triolein-; CO-, and PNPB-hydrolyzing activities were essentially identical. Only one polypeptide of Mr 84,000 in partial purified HSL fraction was labeled by affinity labeling with [3H]DFP. On digestion of the enzyme with trypsin, the triolein- and CO-hydrolyzing activities were lost more rapidly than the PNPB-hydrolyzing activity. Phosphorylation increased the triolein-hydrolyzing activity to 40% more than that of the control, but did not affect the CO- and PNPB-hydrolyzing activities.     

Sucrose consumption in mice: Major influence of two genetic Loci affecting peripheral sensory responses

Individual variability in sucrose consumption is prominent in humans and other species. To investigate the genetic contribution to this complex behavior, we conducted behavioral, electrophysiological, and genetic studies, using male progeny of two inbred mouse strains (C57BL/6ByJ [B6] and 129/J [129]) and their F₂ hybrids. Two loci on Chromosome (Chr) 4 were responsible for over 50% of the genetic variability in sucrose intake. These loci apparently modulated intake by altering peripheral neural responses to sucrose. One locus affected the response threshold, whereas the other affected the response magnitude. These findings suggest that the majority of difference in sucrose intake between male B6 and 129 mice is due to polymorphisms of two genes that influence receptor or peripheral nervous system activity. Received: 27 January 1997 / Accepted: 17 March 1997     

Identification of 19-nor-deoxycorticosterone in normal rat serum by enzyme immunoassay and gas chromatography-mass spectrometry

Recent reports on the isolation and identification of 19-nor-deoxycorticosterone from the urine of rats with adrenal regeneration hypertension give rise to the possibility of a role of this steroid in the pathogenesis of low renin essential hypertension. The present study was undertaken to investigate the presence of 19-nor-deoxycorticosterone in normal rat serum both by a sensitive enzyme immunoassay and by gas chromatography-mass spectrometry (GC/MS). 19-Nor-deoxycorticosterone in rat serum was separated from other steroids prior to enzyme immunoassay by using high performance liquid chromatography (HPLC). The average concentration of 19-nor-deoxycorticosterone in normal rat serum was 137 +/- 62 ng/dl (mean +/- SD, n = 32). Pooled normal rat serum (50 ml) was purified by HPLC and the purified sample was acetylated with acetic anhydride for GC/MS measurement. The retention time and m/z ions (358, 285, and 257) on the resulting mass fragmentogram coincided in position with those of authentic 21-acetoxy-19-nor-deoxycorticosterone and acetylated normal rat serum extract. The combined characteristics of HPLC elution, antigen-antibody reaction, GC retention and selected ion responses provided strongly evidence supporting the presence of 19-nor-deoxycorticosterone in normal rat serum.     

Chromatographic separation, of extracellular acid phosphatase of tobacco cells cultured under Pi-supplied and omitted conditions

An extracellular acid phosphatase preparation of tobacco XD-6cells cultured in suspension was resolved into three fractionsby sequential chromatography. Two of these were neutral pyrophosphatasewith diesterase activity, having optimum pH at 6.8. The otheris a nonspecific acid phosphatase having optimum pH at 5.8.The latter was concluded to be involved in the increase in extracellularactivity upon Pi-depletion. (Received August 31, 1976; )     

Microbial Resolution of alpha-Hydroxy Acids by Enantiospecifically Dehydrogenating Bacteria from Soil

Thirty-three bacterial strains were isolated from soil, utilizing optically asymmetric degradation of dl-2-hydroxy-4-methylpentanoic acid (dl-HMPA) as the screening probe. Those strains were distributed in the following group and genera: Coryneform and Bacillus, Pseudomonas, and Streptomyces. Among them, the most potent strains, Bacillus freudenreichii NRS-137KH20B and Brevibacterium albidum NRS-130KH20B, could perform the resolution of more than 30 g of dl-HMPA per liter within 4 to 5 days of fermentation. Optically pure l- and d-HMPA enantiomers were obtained in more than 80% theoretical yield, whereas the transformed enantiomer was almost quantitatively recovered as 2-oxo-4-methyl-pentanoic acid in the culture broth. The enantiospecific dehydrogenation responsible for this resolution reaction had a rather wide substrate specificity on straight or branched aliphatic C(4) to C(16) 2-hydroxy acids, exhibiting the optima at chain lengths of either C(7) or C(5), although the enantiospecificity was not changed by chain length. The process was thus successfully extended to the preparation of optically pure C(5) to C(9) 2-hydroxy acids.     

The human complement regulatory protein CD59 binds to the alpha-chain of C8 and to the "b"domain of C9.

The erythrocyte membrane inhibitor of the human terminal complement proteins, surface antigen CD59, has previously been shown to enter into a detergent-resistant complex with either the membrane-bound complex of C5b-8 or C5b-9 (Meri, S., Morgan, B. P., Davies, A., Daniels, R. H., Olavesen, M. G., Waldmann, H. and Lachmann, P. J. (1990) Immunology 71, 1-9; Rollins, S. A., Zhao, J., Ninomiya, H., and Sims, P. J. (1991) J. Immunol, 146, 2345-2351). In order to further define the interactions that underlie the complement-inhibitory function of CD59, we have examined the binding interactions between 125I-CD59 and the isolated components of human complement membrane attack complex, C5b6, C7, C8, and C9. By density gradient analysis, we were unable to detect interaction of 125I-CD59 with any of these isolated complement components in solution. Specific binding of 125I-CD59 to C8 and C9 was detected when these human complement proteins were adsorbed to either plastic or to nitrocellulose, suggesting that a conformational change that accompanies surface adsorption exposes a CD59-binding site that is normally buried in these serum proteins. The binding of 125I-CD59 to plastic-adsorbed C8 and C9 was saturable and competed by excess unlabeled CD59, with half-maximal binding observed at 125I-CD59 concentrations of 80 and 36 nM, respectively. No specific binding of 125I-CD59 was detected for surface-adsorbed human C5b6 or C7 nor was such binding observed for C8 or C9 isolated from rabbit serum. Binding of CD59 to human C8 and C9 was not mediated by the phospholipid moiety of CD59, implying association by protein-protein interaction. In order to further define the binding sites for CD59, ligand blotting with 125I-CD59 was performed after separation of C8 into its noncovalently associated subunits (C8 alpha-gamma and C8 beta) and after alpha-thrombin digestion of C9. These experiments revealed specific and saturable binding of 125I-CD59 to C8 alpha-gamma subunit (half-maximal binding at 75 nM), but not to C8 beta, and specific and saturable binding to the 37-kDa fragment (C9b) of thrombin-cleaved C9 (half-maximal binding at 35 nM), but not to the 25-kDa C9a fragment. Partial reduction of C8 alpha-gamma revealed that only C8 alpha polypeptide exhibited affinity for CD59, and no specific binding to the C8 gamma chain was detected.(ABSTRACT TRUNCATED AT 400 WORDS)     

Solid phase fluoroimmunoassay for 11-deoxycortisol in serum using 21-amino-17-hydroxyprogesterone

Solid phase fluoroimmunoassay of serum 11-deoxycortisol (17,21-dihydroxy-4-pregnene-3,20-dione) was established using fluorescein isothiocyanate-labelled 11-deoxycortisol and anti-11-deoxycortisol antibody-conjugated polyacrylamide beads. 21-Amino-17-hydroxyprogesterone (21-amino-17-hydroxy-4-pregnene-3,20-dione) was synthesized as a useful derivative for preparing the fluorescent dye conjugate. Serum 11-deoxycortisol was measured with this assay system after extraction and purification by Sephadex LH-20 column chromatography. The minimal amount of 11-deoxycortisol detected was 40 pg/tube and the measurable range was from 0.04 to 5.0 microgram/dl. Intra- and inter-assay coefficients of variation were 8.3% (n=6) and 9.8% (n=5), respectively. 11-deoxycortisol values determined by the present assay correlated well with those determined by radioimmunoassay. The present assay is particularly suitable for estimating the conditions of the pituitary and adrenocortical functions.