scholarly journals The effect of polyamines on the poly(adenylic acid)-induced inhibition of ribonuclease activity

1981 ◽  
Vol 193 (1) ◽  
pp. 325-337 ◽  
Author(s):  
T P Karpetsky ◽  
K K Shriver ◽  
C C Levy
Keyword(s):  
Human Plasma ◽  
Segment Length ◽  
Side Chain ◽  
Amino Groups ◽  
Human Spleen ◽  
Low Concentrations ◽  
Degradation Rates ◽  
Adenylic Acid ◽  
Bovine Pancreas ◽  
Terminal Poly

Segments of poly(A) at the 3′-termini of 5 S rRNA inhibit the activities of ribonucleases from Citrobacter, Enterobacter, bovine pancreas, human spleen and human plasma. Certain polyamines, or compounds containing polyamine substructures, mediate reversal of this inhibition. Effective compounds contain three amino groups, at least two of which are charged and are separated from the others by no less than three carbon atoms. Spermidine and 9-aminoacridines, which contain substituted propyl- or butylamino moieties at the 9-amino position and which bear two positive charges per molecule, are efficacious at low concentrations (5 microM). A decrease in effectiveness is associated with the removal of one aromatic ring from the 9-aminoacridines. However, the resulting 4-aminoquinolines, unlike the acridines, do not inhibit enzyme activity when present in concentrations above 30 microM. Relocating the diamino side chain from the 4- to the 8-position of the quinoline nucleus causes a decrease in charge density to +1, with the result that such compounds are ineffective. The orders of polyamine efficacy of reversal of inhibition were similar for enzymes from Citrobacter, bovine pancreas, and human plasma, and paralleled the order of binding of polyamines to either poly(A) or 5 S rRNA. This was not the case with Enterobacter and human spleen RNAases, indicating that the identity of the most effective polyamines depends on the RNAase studied. The combination of variable 3′-terminal poly(A) segment length and polyamine identity and concentration constitutes a system by which RNAase activities, and, therefore, substrate-degradation rates, may be easily varied.

scholarly journals Poly(adenylic acid) in small amounts, free or covalently linked to substrate, protects RNA from hydrolysis by ribonuclease

1981 ◽  
Vol 193 (1) ◽  
pp. 311-324 ◽  
Author(s):  
T P Karpetsky ◽  
K K Shriver ◽  
C C Levy
Keyword(s):  
Enzyme Activity ◽  
Segment Length ◽  
Human Spleen ◽  
Fixed Amount ◽  
Polyadenylic Acid ◽  
Adenylic Acid ◽  
Covalently Linked ◽  
The Stability ◽  
Bovine Pancreas ◽  
Small Subpopulation

Short lengths (18 residues) of poly(A), covalently linked to the 3′-termini of Escherichia coli 5 S rRNA, induce powerful inhibitions (38-87%) of the activities of RNAases (ribonucleases) from Citrobacter sp., Enterobacter sp., bovine pancreas, human spleen and human plasma. As the polypurine chain length is extended, enzyme activity declines. Furthermore, poly(A) sequences, present only on a small subpopulation of RNA, and accounting for less than 1% of total RNA, serve to protect all RNA, polyadenylated or not, from enzyme-catalysed degradation. The quantity of 3′-terminal adenylic acid residues, relative to the amount of substrate, determines enzyme activity. The exact distribution of a fixed amount of poly(A) residues on the 3′-termini of substrate molecules is unimportant in this respect. Comparison of the efficacies of inhibition of RNAase activity, by using linked poly(A) and similar quantities of free poly(A), revealed that although the free polypurine inhibits RNAase activity, covalent linkage of poly(A) to RNA is more advantageous to the stability of an RNA substrate. However, the ratio of inhibited activities obtained by using linked or free poly(A) may change considerably with alterations in either substrate concentration or polyadenylic acid segment length.

Biodegradation rates of aromatic contaminants in biofilm reactors

1995 ◽  
Vol 31 (1) ◽  
pp. 117-128 ◽  
Author(s):  
Jean-Pierre Arcangeli ◽  
Erik Arvin
Keyword(s):  
Aromatic Hydrocarbons ◽  
Competitive Inhibition ◽  
Removal Rate ◽  
First Order ◽  
Biofilm Reactors ◽  
First Order Kinetics ◽  
Reducing Conditions ◽  
Low Concentrations ◽  
Degradation Rates ◽  
Order Surface

This study has shown that microorganisms can adapt to degrade mixtures of aromatic pollutants at relatively high rates in the μg/l concentration range. The biodegradation rates of the following compounds were investigated in biofilm systems: aromatic hydrocarbons, phenol, methylphenols, chlorophenols, nitrophenol, chlorobenzenes and aromatic nitrogen-, sulphur- or oxygen-containing heterocyclic compounds (NSO-compounds). Furthermore, a comparison with degradation rates observed for easily degradable organics is also presented. At concentrations below 20-100 μg/l the degradation of the aromatic compounds was typically controlled by first order kinetics. The first-order surface removal rate constants were surprisingly similar, ranging from 2 to 4 m/d. It appears that NSO-compounds inhibit the degradation of aromatic hydrocarbons, even at very low concentrations of NSO-compounds. Under nitrate-reducing conditions, toluene was easily biodegraded. The xylenes and ethylbenzene were degraded cometabolically if toluene was used as a primary carbon source; their removal was influenced by competitive inhibition with toluene. These interaction phenomena are discussed in this paper and a kinetic model taking into account cometabolism and competitive inhibition is proposed.

Rapid screening for deficiency of alpha 1-proteinase inhibitor.

1989 ◽  
Vol 35 (9) ◽  
pp. 1971-1975 ◽  
Author(s):  
C Lloyd ◽  
J Travis
Keyword(s):  
Human Plasma ◽  
Inhibitory Activity ◽  
Proteinase Inhibitor ◽  
Rapid Screening ◽  
Early Screening ◽  
Pancreatic Elastase ◽  
Low Concentrations ◽  
Normal Individuals ◽  
Porcine Pancreatic Elastase ◽  
Alpha 1 Antitrypsin

Abstract This rapid screening procedure for detection of low but functional elastase-inhibitory activity in human plasma is based on the fact that incubation of excess porcine pancreatic elastase (EC 3.4.21.36) with plasma results in formation of a complex with active alpha 1-proteinase inhibitor (alpha 1PI, also called alpha 1-antitrypsin). In normal individuals all of the elastase is complexed, leaving no free enzyme to hydrolyze the elastase substrate, and the reaction mixture remains clear. Because individuals homozygous for the Z allele have relatively low concentrations of alpha 1PI, their plasma cannot complex all of the elastase in the assay. The uncomplexed enzyme hydrolyzes the elastase-specific p-nitroanilide substrate, producing a yellow reaction mixture. Use of this simple assay for early screening of individuals for alpha 1PI deficiency may substantially decrease the number of untreated cases of familial emphysema, a disorder that develops as a result of a genetically derived proteinase-proteinase inhibitor imbalance.

High-throughput determination of ultra-low concentrations of LAG078, a lipid modulator, in human plasma

2005 ◽  
Vol 37 (5) ◽  
pp. 1039-1048
Author(s):  
Tapan K. Majumdar ◽  
Ray Bakhtiar ◽  
Cindy Chen ◽  
Luis Ramos ◽  
Francis L.S. Tse
Keyword(s):  
Human Plasma ◽  
High Throughput ◽  
Low Concentrations

Enhanced stability and gene silencing ability of siRNA-loaded polyion complexes formulated from polyaspartamide derivatives with a repetitive array of amino groups in the side chain

Biomaterials ◽  
2012 ◽  
Vol 33 (9) ◽  
pp. 2770-2779 ◽  
Author(s):  
Tomoya Suma ◽  
Kanjiro Miyata ◽  
Takehiko Ishii ◽  
Satoshi Uchida ◽  
Hirokuni Uchida ◽  
...  
Keyword(s):  
Gene Silencing ◽  
Side Chain ◽  
Amino Groups ◽  
Enhanced Stability ◽  
Polyion Complexes

scholarly journals Chemical Reactivities of ortho-Quinones Produced in Living Organisms: Fate of Quinonoid Products Formed by Tyrosinase and Phenoloxidase Action on Phenols and Catechols

2020 ◽  
Vol 21 (17) ◽  
pp. 6080 ◽  
Author(s):  
Shosuke Ito ◽  
Manickam Sugumaran ◽  
Kazumasa Wakamatsu
Keyword(s):  
Nucleophilic Addition ◽  
Quinone Methide ◽  
Side Chain ◽  
Amino Groups ◽  
Melanin Biosynthesis ◽  
Fast Reactions ◽  
Carcinogenic Effects ◽  
Oxidation Of Phenols ◽  
Living Organisms ◽  
Cellular Components

Tyrosinase catalyzes the oxidation of phenols and catechols (o-diphenols) to o-quinones. The reactivities of o-quinones thus generated are responsible for oxidative browning of plant products, sclerotization of insect cuticle, defense reaction in arthropods, tunichrome biochemistry in tunicates, production of mussel glue, and most importantly melanin biosynthesis in all organisms. These reactions also form a set of major reactions that are of nonenzymatic origin in nature. In this review, we summarized the chemical fates of o-quinones. Many of the reactions of o-quinones proceed extremely fast with a half-life of less than a second. As a result, the corresponding quinone production can only be detected through rapid scanning spectrophotometry. Michael-1,6-addition with thiols, intramolecular cyclization reaction with side chain amino groups, and the redox regeneration to original catechol represent some of the fast reactions exhibited by o-quinones, while, nucleophilic addition of carboxyl group, alcoholic group, and water are mostly slow reactions. A variety of catecholamines also exhibit side chain desaturation through tautomeric quinone methide formation. Therefore, quinone methide tautomers also play a pivotal role in the fate of numerous o-quinones. Armed with such wide and dangerous reactivity, o-quinones are capable of modifying the structure of important cellular components especially proteins and DNA and causing severe cytotoxicity and carcinogenic effects. The reactivities of different o-quinones involved in these processes along with special emphasis on mechanism of melanogenesis are discussed.

scholarly journals Conformational changes at the active site of creatine kinase at low concentrations of guanidinium chloride

1993 ◽  
Vol 291 (1) ◽  
pp. 103-107 ◽  
Author(s):  
H M Zhou ◽  
X H Zhang ◽  
Y Yin ◽  
C L Tsou
Keyword(s):  
Creatine Kinase ◽  
Fluorescent Probe ◽  
Conformational Change ◽  
Conformational Changes ◽  
Active Site ◽  
Emission Intensity ◽  
Enzyme Inactivation ◽  
Amino Groups ◽  
Guanidinium Chloride ◽  
Low Concentrations

It has been previously reported that, during denaturation of creatine kinase by guanidinium chloride (GdmCl) or urea [Tsou (1986), Trends Biochem. Sci. 11, 427-429], inactivation occurs before noticeable conformational change can be detected, and it is suggested that the conformation at the active site is more easily perturbed and hence more flexible than the molecule as a whole. In this study, the thiol and amino groups at or near the active site of creatine kinase are labelled with o-phthalaldehyde to form a fluorescent probe. Both the emission intensity and anisotropy decrease during denaturation indicating exposure of this probe and increased mobility of the active site. The above conformational changes take place together with enzyme inactivation at lower GdmCl concentrations than required to bring about intrinsic fluorescence changes of the enzyme. At the same GdmCl concentration, the rate of exposure of the probe is comparable with that of inactivation and is several orders of magnitude faster than that for the unfolding of the molecule as a whole.

scholarly journals Different molecular forms of plasminogen and plasmin produced by urokinase in human plasma and their relation to protease inhibitors and lysis of fibrinogen and fibrin

1974 ◽  
Vol 143 (2) ◽  
pp. 273-283 ◽  
Author(s):  
Sten Müllertz
Keyword(s):  
Human Plasma ◽  
Protease Inhibitors ◽  
Gel Electrophoresis ◽  
Protease Activity ◽  
Gel Filtration ◽  
Molecular Forms ◽  
Crossed Immunoelectrophoresis ◽  
Low Concentrations ◽  
Α2 Macroglobulin ◽  
Esterase Inhibitor

Urokinase-activated human plasma was studied by gel electrophoresis, gel filtration, crossed immunoelectrophoresis and electroimmunoassay with specific antibodies and by assay of esterase and protease activity of isolated fractions. Urokinase induced the formation of different components with plasminogen+plasmin antigenicity. At low concentrations of urokinase, a component with a KD value of 0.18 by gel filtration and post β1 mobility by gel electrophoresis was detected. The isolated component had no enzyme or plasminogen activity. In this plasma sample fibrinogen was not degraded for 10h, but when fibrin was formed, by addition of thrombin, fibrin was quickly lysed, and simultaneously a component with a KD value of 0 and α2 mobility appeared, which was probably plasmin in a complex with α2 macroglobulin. This complex showed both esterase and protease activity. After gel filtration with lysine buffer of the clotted and lysed plasma another two components were observed with about the same KD value by gel filtration as plasminogen (0.35), but β1 and γ mobilities by gel electrophoresis. They appeared to be modified plasminogen molecules, and possibly plasmin with γ mobility. Similar processes occurred without fibrin at higher urokinase concentrations. Here a relatively slow degradation of fibrinogen was correlated to the appearance of the plasmin–α2 macroglobulin complex. The fibrin surface appeared to catalyse the ultimate production of active plasmin with a subsequent preferential degradation of fibrin and the formation of a plasmin–α2 macroglobulin complex. The gel filtration and electrophoresis of the plasma protease inhibitors, α1 antitrypsin, inter-α-inhibitor, antithrombin III, and C1-esterase inhibitor indicated that any complex between plasmin and these inhibitors was completely dissociated. The β1 and post β1 components appear to lack correlates among components occurring in purified preparations of plasminogen and plasmin.

A radioimmunoassay for bone Gla protein (BGP) in human plasma

1987 ◽  
Vol 114 (3) ◽  
pp. 410-416 ◽  
Author(s):  
Julia S. Johansen ◽  
J. E. Mølholm Hansen ◽  
Claus Christiansen
Keyword(s):  
Renal Failure ◽  
Chronic Renal Failure ◽  
Human Plasma ◽  
Biochemical Marker ◽  
Normal Subjects ◽  
Bone Gla Protein ◽  
Low Concentrations ◽  
Metabolic Bone ◽  
The Mean ◽  
Bone Physiology

Abstract. To study the value of bone Gla protein (BGP) as a biochemical marker of normal bone physiology and metabolic bone disorders, we have developed a radioimmunoassay (RIA) for the detection of BGP in human plasma. Antibodies were generated in rabbits immunized with purified calf BGP conjugated to thyroglobulin. Human plasma BGP reacted identically with the calf BGP standard, thus demonstrating the suitability of the assay to measure plasma BGP levels in man. The RIA is sensitive, accurate, and technically simple. Plasma BGP levels were determined in normal subjects (N = 35) and in patients with hypothyroidism (N = 10), hyperthyroidism (N = 22) and chronic renal failure (N = 35). The mean (± 1 sem) concentration of plasma BGP in normal subjects was 1.27 ± 0.07 nmol/l. Plasma BGP was significantly increased in patients with hyperthyroidism, 4.04 ± 0.78 nmol/l (P < 0.001) and chronic renal failure, 10.17 ± 2.47 nmol/l (P < 0.001). Low concentrations were found in patients with hypothyroidism, 0.74 ± 0.11 nmol/l (P <0.01). Our studies indicate that plasma BGP provides a useful technique in the diagnosis of patients with bone disease.

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