Perspectives on Discovery of Microbial Phytotoxins with Herbicidal Activity

1988 ◽  
Vol 2 (4) ◽  
pp. 525-532 ◽  
Author(s):  
Horace G. Cutler
Keyword(s):  
Natural Products ◽  
Root Growth ◽  
Specific Activity ◽  
High Specific Activity ◽  
Herbicidal Activity ◽  
Biologically Active ◽  
Natural State ◽  
Natural Herbicides ◽  
Synthetic Derivative ◽  
Inhibit Root Growth

Biologically active natural products of microbial origin are attractive candidates for possible use in agriculture. They may be obtained by fermentation, used in their natural state, or subjected to synthetic modification for specific uses. These natural products are characterized by high specific activity and high selectivity, and they are biodegradable. The structures are extremely diverse and represent many classes of compounds ranging from very complex to simple. Cyclocarbamide A and B, fromStreptoverticilliumsp., have marked preemergence herbicidal activity. Nigerazine A and B, fromAspergillus nigervan Tieghem, also inhibit root growth in certain plants. Citreoviridin, fromPenicillium charlesiiSmith, preferentially controls the growth of monocotyledonous plants, as does a synthetic derivative of cladosporin, fromAspergillus repensDeBary, which bleaches chloroplasts. The 12-membered fungal macrolides (macrocyclic lactones) also inhibit root growth in many test plants and offer templates for further synthetic work. Herbicidins, fromStreptomyces saganonensis, are particularly effective against barnyardgrass, goosegrass, tufted mannagrass, and green panicum.Alternaria eichorniaeNag Raj et Ponnappa produces a toxin that is active against waterhyacinth and represents one of the more exotic structures. The macrocyclic trichothecenes are a significant class of natural products that tend to concentrate against a gradient in seeds of certain plants, which resist these microbially derived metabolites thereby producing seed with “built-in” natural herbicides.

Peripheral metabolism of PTH: fate of biologically active amino terminus in vivo

1988 ◽  
Vol 255 (6) ◽  
pp. E886-E893 ◽  
Author(s):  
F. R. Bringhurst ◽  
A. M. Stern ◽  
M. Yotts ◽  
N. Mizrahi ◽  
G. V. Segre ◽  
...  
Keyword(s):  
Specific Activity ◽  
Limited Proteolysis ◽  
High Specific Activity ◽  
Biologically Active ◽  
Amino Terminal ◽  
Liver And Kidney ◽  
Low Levels ◽  
Peripheral Metabolism

Clearance of intact parathyroid hormone (PTH) from blood is associated with rapid uptake by liver and kidney, limited proteolysis by tissue endopeptidases and, within minutes, appearance of circulating carboxyl-(COOH)-terminal PTH fragments. The fate of the corresponding amino(NH2)-terminal portion of the hormone during this peripheral metabolism is still unknown, however. To determine this, we have employed [35S]bovine PTH (bPTH) labeled to high specific activity at NH2-terminal methionines, which permits direct monitoring of the fate of the PTH NH2-terminus during metabolism in vivo. The [35S]PTH was administered by bolus or continuous intravenous infusion to anesthetized normal rats, to rats subjected to acute ablation of the liver, the kidneys, or both, and to rats receiving co-infusions of excess synthetic bPTH(1-34) NH2-terminal fragments. Analysis by high-resolution chromatographic techniques sensitive to 10(-13) M [35S]PTH peptides in plasma yields no evidence that peripheral metabolism of PTH generates circulating NH2-terminal fragments, even when special measures are taken to block clearance of such putative fragments from blood. We find that the NH2-terminus of PTH is rapidly degraded in situ by the liver but that both liver and especially kidney nevertheless contain low levels of NH2-terminal PTH fragments that, although not released into the blood, are large enough to be potentially active. Thus, the peripheral metabolism of PTH in normal animals does not normally lead to the formation of circulating amino terminal fragments of the hormone that might act independently of intact PTH on peripheral target tissues.

High specific activity tritiation of several biologically active indoles

2011 ◽  
Vol 69 (2) ◽  
pp. 423-425 ◽  
Author(s):  
Richard P. Nugent ◽  
Scot Pounds ◽  
Crist N. Filer
Keyword(s):  
Specific Activity ◽  
High Specific Activity ◽  
Biologically Active

scholarly journals Identification and purification of natural killer cell stimulatory factor (NKSF), a cytokine with multiple biologic effects on human lymphocytes.

1989 ◽  
Vol 170 (3) ◽  
pp. 827-845 ◽  
Author(s):  
M Kobayashi ◽  
L Fitz ◽  
M Ryan ◽  
R M Hewick ◽  
S C Clark ◽  
...  
Keyword(s):  
Molecular Conformation ◽  
Nk Cell ◽  
Specific Activity ◽  
Biological Activities ◽  
Human Lymphocytes ◽  
Killer Cell ◽  
High Specific Activity ◽  
Biologically Active ◽  
Biologic Effects ◽  
Stimulatory Factor

We have identified and purified a novel cytokine, NK cell stimulatory factor (NKSF), from the cell-free supernatant fluid of the phorbol diester-induced EBV-transformed human B lymphoblastoid cell line RPMI 8866. NKSF activity is mostly associated to a 70-kD anionic glycoprotein. The purified 70-kD protein, isolated from an SDS-PAGE gel, yields upon reduction two small species of molecular masses of 40 and 35 kD, suggesting that this cytokine is a heterodimer. When added to human PBL, purified NKSF preparations induce IFN-gamma production and synergize with rIL-2 in this activity, augment the NK cell-mediated cytotoxicity of PBL preparations against both NK-sensitive and NK-resistant target cell lines, and enhance the mitogenic response of T cells to mitogenic lectins and phorbol diesters. The three activities remain associated through different purification steps resulting in a 9,200-fold purification, and purified NKSF mediates the three biological activities at concentrations in the range of 0.1-10 pM. These data strongly suggest that the same molecule mediates these three activities, although the presence of traces of contaminant peptides even in the most purified NKSF preparations does not allow us to exclude the possibility that distinct biologically active molecules have been co-purified. The absence of other known cytokines in the purified NKSF preparations, the unusual molecular conformation of NKSF, the high specific activity of the purified protein, and the spectrum of biological activities distinguish NKSF from other previously described cytokines.

Biologically active natural products from Cassine viburnifolia

Planta Medica ◽  
2015 ◽  
Vol 81 (11) ◽  
Author(s):  
T Grkovic ◽  
R Akee ◽  
J Evans ◽  
JM Collins ◽  
B O'Keefe
Keyword(s):  
Natural Products ◽  
Biologically Active ◽  
Active Natural

Effects of Heparin Oligosaccharides with High Affinity for Antithrombin III in Experimental Venous Thrombosis

1982 ◽  
Vol 47 (03) ◽  
pp. 244-248 ◽  
Author(s):  
D P Thomas ◽  
Rosemary E Merton ◽  
T W Barrowcliffe ◽  
L Thunberg ◽  
U Lindahl
Keyword(s):  
Antithrombin Iii ◽  
Specific Activity ◽  
High Specific Activity ◽  
Factor Xa ◽  
Blood Levels ◽  
Thrombin Time ◽  
High Affinity ◽  
Very High

SummaryThe in vitro and in vivo characteristics of two oligosaccharide heparin fragments have been compared to those of unfractionated mucosal heparin. A decasaccharide fragment had essentially no activity by APTT or calcium thrombin time assays in vitro, but possessed very high specific activity by anti-Factor Xa assays. When injected into rabbits at doses of up to 80 ¼g/kg, this fragment was relatively ineffective in impairing stasis thrombosis despite producing high blood levels by anti-Xa assays. A 16-18 monosaccharide fragment had even higher specific activity (almost 2000 iu/mg) by chromogenic substrate anti-Xa assay, with minimal activity by APTT. When injected in vivo, this fragment gave low blood levels by APTT, very high anti-Xa levels, and was more effective in preventing thrombosis than the decasaccharide fragment. However, in comparison with unfractionated heparin, the 16-18 monosaccharide fragment was only partially effective in preventing thrombosis, despite producing much higher blood levels by anti-Xa assays.It is concluded that the high-affinity binding of a heparin fragment to antithrombin III does not by itself impair venous thrombogenesis, and that the anti-Factor Xa activity of heparin is only a partial expression of its therapeutic potential.

Autoprothrombin C Activity from Prothrombin with Snake Venom or Trypsin

1962 ◽  
Vol 08 (03) ◽  
pp. 425-433 ◽  
Author(s):  
Ewa Marciniak ◽  
Edmond R Cole ◽  
Walter H Seegers
Keyword(s):  
Snake Venom ◽  
Thrombolytic Agent ◽  
Sodium Citrate ◽  
Specific Activity ◽  
High Specific Activity ◽  
Citrate Solution ◽  
Clotting Factors ◽  
Activation Products ◽  
Russell’S Viper ◽  
Autoprothrombin C

SummarySuitable conditions were found for the generation of autoprothrombin C from purified prothrombin with the use of Russell’s viper venom or trypsin. DEAE chromatographed prothrombin is structurally altered and has never been found to yield autoprothrombin C and also did not yield it when Russell’s viper venom or trypsin were used. Autoprothrombin C is derived from prothrombin with tissue extract thromboplastin, but not in large amounts with the intrinsic clotting factors. With the latter thrombin and autoprothrombin III are the chief activation products. Autoprothrombin III concentrates were prepared from serum and upon activation with 25% sodium citrate solution or with Russell’s viper venom large amounts of autoprothrombin C were obtained, and this was of high specific activity. Theoretically trypsin is not a thrombolytic agent, but on the contrary should lead to intravascular clotting.

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