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Determination of the mechanism and kinetic constants for hog kidney gamma-glutamyltransferase.

The initial-velocity kinetics of hog kidney gamma-glutamyltransferase were studied. Glutamate gamma-(4-nitroanilide) and its 3-carboxy derivative, glutamate gamma-(3-carboxy-4-nitroanilide), served as gamma-glutamyl donors, and glycylglycine as an acceptor. Reaction products were identified by paper chromatography and amino acid analysis. Inhibited Ping Pong mechanisms and a comprehensive initial- velocity expression were developed which account for the observed simultaneous gamma-glutamyl transfer and autotransfer, competitive inhibition by glycylglycine, and non-competitive inhibition by the carboxy donor. The validity of the proposed Ping Pong mechanisms are supported by enzyme-velocity data obtained with constant ratios of acceptor to donor concentrations. Kinetic constants were determined by a non-linear regression analysis. With glutamate gamma-(4-nitroanilide) as the donor, Michaelis constants for the donor, acceptor and donor-acting-as-acceptor are 1.87, 24.9, and 2.08 mM respectively. With glutamate gamma-(3-carboxy-4-nitroanilide) as the donor, these Michaelis constants are 1.63, 16.6, and 12.3 mM. Glyclyglycine competitive inhibition constants with the parent donor and its carboxy derivative are 275 and 205 mM respectively; the non-competitive inhibition constant of the carboxy donor is 34 mM.

Anilides↗

Intracellular and extracellular sites of iodination in dispersed hog thyroid cells.

Iodination and hormone synthesis has been studied in isolated hog thyroid cells in suspension. We characterized three iodination processes by use of pharmacological agents. (1) Intracellular iodination dependent on active iodide transport, which was inhibited by NaClO4 or ouabain, but not by catalase. This iodination was linear for 6h with no apparent Km for iodide of 1.5 muM, was stimulated by thyrotropin or N6O2'-dibutyryladenosine 3':5'-cyclic monophosphate, yielded mostly iodinated thyroglobulin and was efficient for tetraiodothyronine synthesis. (2) Extracellular iodination, which was sensitive to catalase, but not to NaClO4 or ouabain. This iodination plateaued after 2h and the apparent Km was 16.5 muM. This process was insensitive to thyrotropin and dibutyryl cyclic AMP. The major products were iodoprotein other then thyroglobulin and iodolipid and the yield of tetraiodothyronine was low. (3) Intracellular iodination from passively diffused iodide, which was not sensitive to inhibitors. Other characteristics of passive intracellular iodination were intermediate between active intracellular iodination and extracellular iodination. The fact that the three processes are inhibited by similar concentrations of methimazole, and their apparent Km values, when corrected for the concentrating effect of iodide trapping, are all of the same order as the Km of purified thyroid peroxidases, suggest that although their locations are different, the enzymic systems involved are identical. These results show that, besides an extracellular site of iodination, dispersed thyroid cells process an intracellular site of iodination with biochemical characteristics of physiological relevance.

Animals↗

Renin precursor and its activation mechanism in hog kidney.

1. A completely inactive renin was isolated from hog kidney extract by affinity chromatography on pepstatin-aminohexyl-Sepharose and on an Affi-Gel Blue column. 2. This inactive renin had a molecular weight of 43 000 +/- 1500 as determined by gel filtration on Ultrogel AcA 44. Upon activation with trypsin, its molecular weight fell to 41 000 +/- 1400. 3. The inactive renin lacked the ability to bind renin-binding substance whereas trypsin-activated renin was able to bind the renin-binding protein and to form high-molecular-weight renin. 4. Chymotrypsin as well as trypsin could activate the inactive renin although less effectively. 5. The active renins generated from the inactive renin by the action of different proteolytic enzymes differed in their net charge, reflecting the specificities of the proteases used; the isoelectric points of the native, the trypsin-activated and the chymotrypsin-activated forms of renin occurred at pH 5.3, 5.1 and 4.8 respectively.

Animals↗

Characterization of lesions caused by a South American virulent isolate ('Quillota') of the hog cholera virus.

In this study, macroscopic and histopathological lesions produced by a virulent South American isolate ('Quillota') of hog cholera virus were studied. The virus was inoculated in doses of 10(5)TCID50 in each of 35 pigs of 20 kg live weight. The animals were slaughtered from 4 to 18 days post-inoculation. The presence of virus antigens in lymphatic tissue was confirmed by both direct immunofluorescence and Avidin-Biotin-Peroxidase techniques in formalin-embedded tissue samples. Histological sections were stained with haematoxylin-eosin and Mallory's phosphotungstic acid haematoxylin methods. The 'Quillota' isolate used in this study caused a disease characterized by vascular lesions (splenic infarcts, haemorrhages in the lymph nodes and the urinary system and disseminated microthrombosis), and necrosis of lymphocytes, particularly in the B-areas of the lymphoid organs, lesions that are characteristic of the acute form of the disease. Other lesions observed were a non-purulent meningoencephalitis, the necrosis of the epithelial cells of tonsils, the presence of fibrin nets in the red pulp and a marked thickening of the alveolar septa.

Animals↗

Atypical cilia in the bronchiolar epithelium of pigs experimentally infected with hog cholera virus.

To study the effect of hog cholera virus on the epithelial cells of the bronchiolar mucosa, 12 pigs were inoculated with a highly virulent strain. Immunohistochemical and ultrastructural examination of the ciliated epithelial cells demonstrated an increase in the number of atypical cilia. The latter showed alterations in the microtubular pattern, possibly resulting from viral interference with the normal metabolism of the epithelial cells.

Animals↗

Studies on the pituitary "fettstoffwechselhormon". VII. Analytical studies on two lipolytically high active peptides from hog pituitary glands.

First results of analytical studies on the highly purified lipolytic active hog pituitary fractions P-LF II C and P-LF II D are reported. Electrophoresis and end-group determinations indicate homogeneity for both peptides. The molecular weights, amino acid compositions, and the N- and C-terminal sequences of these peptides have been established and are compared with the corresponding results of other laboratories. The relation between biological activity and the structure of lipolytic active peptides is discussed.

Amino Acid Sequence↗

Studies on the pituitary "fettstoffwechselhormon". VI. Preparation of two highly purified lipolytic active peptides from hog pituitary glands.

The preparation of two highly purified lipolytically active hog pituitary peptides, called P-LF II C and P-LF II D is described. The two peptides are free of other pituitary hormone activities. In isolated rat and porcine adipose tissue, both fractions are lipolytically much more active than every other lipolytic active pituitary peptide described to date. By fraction P-LF II D, the first pituitary peptide was isolated which has lipolytic activity in isolated rat adipose tissue than corticotropin, the lipolytically most active pituitary hormone known so far. On isolated porcine adipose tissue, fraction P-LF II D as well as P-LF II C showed without doubt higher activity than corticotropin.

Adipose Tissue↗

Immediate hypersensitivity to hog trypsin resulting from industrial exposure.

Clinical, immunologic and psysiologic studies were undertaken to establish the role of hog trypsin dust in four cases of occupational asthma and to define the mechanism of this respiratory disease. Objective evidence was obtained that these patients, but not their asymptomatic co-workers, were allergic to trypsin, and that this fact accounted for their respiratory symptoms. Direct skin testing, passive transfer of IgE antibodies, antigen-mediated histamine release from peripheral blood leukocytes and airway obstruction in response to inhalation challenge indicated IgE-mediated, Type I hypersensitivity. These effects were induced by inactivated trypsin and were therefore independent of tryptic enzymatic activity. The data suggested that periodic skin testing for immediate sensitivity to organic dust would be an inexpensive and convenient screening procedure for early detection and prevention of some types of occupational asthma.

Aerosols↗

High molecular weight polypeptides (270,000-340,000) from cultured cells are related to hog brain microtubule-associated proteins but copurify with intermediate filaments.

High molecular weight polypeptides (HMWPs) of 270,000 to 340,000 were found to be major components of intermediate filaments prepared by Triton X-100 extraction after spreading of rat glioma C6, HeLa, Chinese hamster ovary, and simian virus 40-transformed Chinese hamster lung cells. C6 HMWPs were shown to resemble high molecular weight microtubule-associated proteins from hog brain by four criteria: (i) comigration in electrophoresis on high-resolution sodium dodecyl sulfate/polyacrylamide gels, (ii) one-dimensional peptide mapping, (iii) phosphorylation in vitro with [gamma-32P]ATP, and (iv) ability to promote microtubule assembly in vitro. HMWPs were also found to be major components of one-time polymerized C6 microtubule preparations, which contained a sizable amount of intermediate filaments. The predominant part of HMWPs present in these microtubule preparations was found not to copurify with microtubules in cycles of temperature-dependent assembly/disassembly but to remain with the cold-insoluble intermediate filaments. These results provide an explanation for the low yields that have hampered attempts to purify microtubule-associated porteins, in particular HMWPs, from cultured cells in the past. Moreover, they suggest that HMWPs might have a dual role in the cell, serving not only as regulators of microtubule assembly but also as linker components between microtubules and intermediate filaments.

Animals↗

Purification and characterization of UDP-GlcNAc:Galbeta1-4GlcNAcbeta1-3*Galbeta1-4Glc(NAc)-R(GlcNAc to *Gal) beta1,6N-acetylglucosaminyltransferase from hog small intestine.

A beta1,6N-acetylglucosaminyltransferase (beta1-6GnT) responsible for the formation of the beta1,6-branched poly-N-acetyllactosamine structure has been purified 210,000-fold in 2.4% yield from a homogenate of hog small intestine by successive column chromatographies involving CM-Sepharose FF, Ni2+-chelating Sepharose FF, and UDP-hexanolamine-agarose, using an assay wherein pyridylaminated lacto-N-neotetraose (Galbeta1-4GlcNAcbeta1-3Galbeta1-4Glc-PA) was used as an acceptor substrate, and the reaction product was Galbeta1-4GlcNAcbeta1-3(GlcNAcbeta1-6)Galbeta1-4 Glc-PA. The apparent molecular weight of the purified enzyme was 76,000 under nonreducing conditions. The enzyme has a pH optimum at 7.0 and has no requirement for any divalent metal ions. The Km values for pyridylaminated lacto-N-neotetraose and UDP-GlcNAc were 0.96 and 2. 59 mM, respectively. For its activity, this enzyme was shown to have an absolute requirement of at least a complete LacNAc (LacNAc = Galbeta1-4GlcNAc) residue bound to position 3 of the acceptor Gal residues, i.e. it is capable of acting only on the Gal residues of internal LacNAc units. The data strongly suggest that this enzyme could be involved in generating branches to central positions of preformed as well as growing polylactosamine chains, but not in synthesizing the distal branches to growing polylactosamine chains.

Amino Sugars↗

A downshift in temperature activates the high osmolarity glycerol (HOG) pathway, which determines freeze tolerance in Saccharomyces cerevisiae.

The molecular mechanisms that enable yeast cells to detect and transmit cold signals and their physiological significance in the adaptive response to low temperatures are unknown. Here, we have demonstrated that the MAPK Hog1p is specifically activated in response to cold. Phosphorylation of Hog1p was dependent on Pbs2p, the MAPK kinase (MAPKK) of the high osmolarity glycerol (HOG) pathway, and Ssk1p, the response regulator of the two-component system Sln1p-Ypd1p. However, Sho1p was not required. Interestingly, phosphorylation of Hog1p was stimulated at 30 degrees C in cells exposed to the membrane rigidifier agent dimethyl sulfoxide. Moreover, Hog1p activation occurred specifically through the Sln1 branch. This suggests that Sln1p monitors changes in membrane fluidity caused by cold. Quite remarkably, activation of Hog1p at low temperatures affected the transcriptional response to cold shock. Indeed, the absence of Hog1p impaired the cold-instigated expression of genes for trehalose- and glycerol-synthesizing enzymes and small chaperones. Moreover, a downward transfer to 12 or 4 degrees C stimulated the overproduction of glycerol in a Hog1p-dependent manner. However, hog1Delta mutant cells showed no growth defects at 12 degrees C as compared with the wild type. On the contrary, deletion of HOG1 or GPD1 decreased tolerance to freezing of wild-type cells preincubated at a low temperature, whereas no differences could be detected in cells shifted directly from 30 to -20 degrees C. Thus, exposure to low temperatures triggered a Hog1p-dependent accumulation of glycerol, which is essential for freeze protection.

Active Transport, Cell Nucleus↗

Optimizing settling conditions for treatment of liquid hog manure.

Sedimentation is a widely used separation method for treating agricultural waste. There are several chemical and biological characteristics, which can affect the settling behavior and liquid waste. The optimization of cation balances and potential for nitrification are among these processes. In addition to sedimentation, it can also affect the dewaterability of the samples. Liquid hog manure was used during the laboratory based experiments to investigate the effects of Ca2+ and Mg2+ ions and nitrification inhibition on the overall settling and dewatering characteristics. The results indicated that settling and dewatering characteristics improved during the course of the experiments. However, the improvement in settling and dewatering characteristics was inconsistent and not statistically significant. Cation addition in aerated reactor increased the highest settling velocity (94%). The improvement in dewaterability, as quantified by capillary suction time, was also not consistent. The greatest filterability observed in the supernatant was a capillary suction time of 40 s for a M:D ratio of 2:1. Initial NH 4 + concentration was more important than the nitrification inhibitor, as the presence of nitrification inhibitor increased the nitrification rate by over 300% because of the high initial NH 4 + concentration and low volatile suspended solid. The results from these experiments provide the basis for further field evaluation of cation optimization.

Agriculture↗

The purification and partial characterization of several forms of hog renin substrate.

Hog renin substrate has been separated into three major (A, B, and C) and two minor forms (D and E) by DEAE cellulose chromatography. Two of the major forms (B and C) have been further fractionated into two additional types (1 and 2) by countercurrent distribution. The purification of substrates A, C(1), and C(2) has been completed. Analysis shows that all three are glycoproteins with molecular weights of about 57,000, and have similar amino acid compositions. Differences exist in the sialic acid, glucosamine, and neutral hexose content, which may account for different physical properties. All the forms of the substrates are attacked by renin at similar rates, and appear to yield the same angiotensin I.

Amino Acids↗

A docking site determining specificity of Pbs2 MAPKK for Ssk2/Ssk22 MAPKKKs in the yeast HOG pathway.

Mitogen-activated protein kinase (MAPK) cascades are conserved signaling modules composed of three sequentially activated kinases (MAPKKK, MAPKK and MAPK). Because individual cells contain multiple MAPK cascades, mechanisms are required to ensure the fidelity of signal transmission. In yeast, external high osmolarity activates the HOG (high osmolarity glycerol) MAPK pathway, which consists of two upstream branches (SHO1 and SLN1) and common downstream elements including the Pbs2 MAPKK and the Hog1 MAPK. The Ssk2/Ssk22 MAPKKKs in the SLN1 branch, when activated, exclusively phosphorylate the Pbs2 MAPKK. We found that this was due to an Ssk2/Ssk22-specific docking site in the Pbs2 N-terminal region. The Pbs2 docking site constitutively bound the Ssk2/Ssk22 kinase domain. Docking site mutations drastically reduced the Pbs2-Ssk2/Ssk22 interaction and hampered Hog1 activation by the SLN1 branch. Fusion of the Pbs2 docking site to a different MAPKK, Ste7, allowed phosphorylation of Ste7 by Ssk2/Ssk22. Thus, the docking site contributes to both the efficiency and specificity of signaling. During these analyses, we also found a nuclear export signal and a possible nuclear localization signal in Pbs2.

Amino Acid Sequence↗

Growth and storage of YAC clones in Hogness Freezing Medium.

To date, frozen storage of YAC libraries have relied on the administration of glycerol to the medium subsequent to cell growth. By adding Hogness Freezing Medium prior to inoculation, cultures can be frozen directly after cell growth, with no adverse effect on the stability of the YAC DNA or on the viability of the cells even after repeated freezing and defrosting. Although a relatively simple modification, the procedure notably improves the handling of YAC libraries and significantly reduces the risk of contamination, especially when dealing with large numbers of clones.

Animals↗

Solubilization, purification, and characterization of (H+, K+)ATPase from hog gastric microsomes.

The (H+,K+)ATPase-enriched microsomal fraction prepared from hog gastric mucosa by sucrose density gradient centrifugation was effectively solubilized with Emulgen, with apparent preservation of the enzyme activity, and then the ATPase was highly purified by polyethylene glycol fractionation, and Blue Sepharose CL-6B and amino-hexyl Sepharose chromatographies. The purified enzyme showed a single band, with an apparent molecular mass of approximately 94 kDa, on SDS-PAGE, and exhibited both K+-ATPase and K+-stimulated-p-nitrophenyl phosphatase (pNPPase) activities. The optimum pH for the ATPase activity was 7.0. Amino acid analysis of the purified enzyme showed that it contains a large amount of hydrophobic amino acid (42%) and a small amount of glucosamine and galactosamine. The rabbit antibody monospecific for the ATPase, in the Ouchterlony double immunodiffusion and Western blotting tests, markedly inhibited both the K+-ATPase and K+-pNPPase activities.

Adenosine Triphosphatases↗

Properties of light and heavy vesicles simultaneously prepared from hog gastric mucosae.

We obtained two kinds of vesicle preparations which were of different density from the same gastric mucosae of hogs stimulated with food before slaughter. Both kinds contained H+,K+-ATPase. The light vesicle preparation differed from the heavy vesicle preparation as follows: the KCl permeability across the membrane of heavy vesicles was larger than that of light vesicles, the actin (46-kDa peptide on SDS-polyacrylamide gel) content of heavy vesicles was much higher than that of light vesicles, and the H+,K+-ATPase activity of heavy vesicles was less sensitive to a monoclonal antibody raised against light vesicles (HK2032) than that of light vesicles. Furthermore, there was a drastic difference in reactivity to SCH 28080, which is an H+,K+-ATPase-specific inhibitor and reacts competitively with the K+-high affinity site. SCH 28080 is more potent in light vesicles than in heavy vesicles. These results suggest that the conformation of H+,K+-ATPase changed during the translocation from tubulovesicles to the apical plasma membrane. On the other hand, H+,K+-ATPase activities in both vesicles had similar pH and [K+] dependences.

Adenosine Triphosphatases↗