UMLS:C0027960 - FACTA Search

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Query: UMLS:C0027960 (mole)
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Candida lipolytica synthesizes the antibiotic tryptanthrin from 1 mole tryptophan and 1 mole anthranilic acid. When feeding tryptophan and substituted anthranilic acids, or substituted tryptophans and anthranilic acid, we could isolate and identify the expected derivatives of tryptanthrin. The enzymes of the biosynthesis of tryptanthrin, with the exception of bromotryptophan, had no specifity for these substrates. In addition to these experiments substituted tryptanthrines were chemically synthesized. We checked them for antibiotic action; the halogen compounds turned out to be especially effective.
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PMID:[Metabolic products of microorganisms. 156. Synthesis and biosynthesis of substituted tryptanthrins (author's transl)]. 81 68

Quaternary salts of 4-picoline are shown to act as efficient quenchers of tryptophan fluorescence in membrane proteins. Fluorescence quenching determinations of sarcoplasmic reticulum membranes from rabbit muscle and of human erythrocyte membranes of different cholesterol to phospholipid mole ratios (C/PL) were carried out with quaternary picolinium salts in phosphate-buffered saline (PBS) and in 2,2,2-trifluorethanol (TFE)-water 2:1 (v/v), where the membrane is presumably completely disintegrated. In both solvent systems, the tryptophan quenching characteristics were typical of heterogenous systems and were analyzed as such. The ratio of the fraction of fluorescence intensity available for quenching with N-methylpicolinium perchlorate in PBS and in 2:1 TFE-water, (formula: see text), was taken as an index for the bulk degree of exposure of the membrane proteins to the aqueous surrounding. This value was found to increase with C/PL which is in line with the notion that increase in lipid microviscosity results in increase of exposure of membrane proteins. Analogous experiments were performed with N-hexyl- and N-benzylpicolinium, which can quench tryptophyl residues in both the aqueous phase and the hydrocarbon-water interface, and with N-hexadecylpicolinium which is dissolved in the membrane lipid layer and acts mostly as a static quencher of tryptophan at the hydrocarbon-water interface. With these quenchers the complementary indices (formula: see text) and (formula: see text), which represent the fraction of the protein mass located in the hydrocarbon-water interface and in the hydrocarbon layer, respectively, could be semiquantitatively resolved.
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PMID:Degree of exposure of membrane proteins determined by fluorescence quenching. 84 25

The acetylation of spinach ferredoxin by acetic anhydride modified about four moles of amino groups. The absorption spectra, CD spectra, the fluorescence of sole tryptophan residue and the biological activity of acetylated ferredoxin were investigated. An equilibrium existed between two different states, D- and N-form, of the acetylated ferredoxin and was dependent on the cation concentration. D-form completely reverted to N-form upon the binding of one mole of cation, Na+ or Mg2+. Although the N-form was indistinguishable from native ferredoxin in every property tested, the D-form was significantly different from the N-form or native ferredoxin and was very unstable, especially at low salt concentrations. It is suggested that the amino groups might be important in maintaining the protein conformation by forming salt linkages, but may not be essential for the activity. Furthermore, since the D-form, unlike the N-form and native ferredoxin, was inactive in the ferredoxin-NADP+ reductase [EC 1.6.7.1] assay system and had no inhibitory effect in this system, it was considered to be incapable of forming a complex with ferredoxin-NADP+ reductase. On the other hand, the N-form of the modified ferredoxin was as active as native ferredoxin. It is suggested that amino groups of spinach ferredoxin are not essential for the redox reaction of ferredoxin or for complex formation with the reductase.
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PMID:Chemical modification of spinach ferredoxin. Properties of acetylated spinach ferredoxin. 84 28

Five proteinase inhibitors which all inhibit the activity of bovine trypsin [EC 3.4.21.4] were isolated from African Elapid venoms of Hemachatus haemachatus (HHV, Ringhal's cobra) and Naja nivea (NNV, Cape cobra). All the inhibitors were essentially homogeneous by polyacrylamide gel electrophoresis in the presence or absence of sodium dodecylsulfate. Amino acid analysis and terminal analysis also supported their chemical homogeneities, except for one of the two inhibitors from Hemachatus haemachatus venom. The isolated inhibitors had a molecular weight of about 6,500, consisting of 52 to 57 amino acid residues, and they were all devoid of tryptophan. However, their amino acid compositions differed from each other. One of the three inhibitors isolated from Naja nivea venom, designated NNV inhibitor Ia, was unique, in that 4 half-cystinyl residues per mole fof the polypeptide were present, whereas all the others contained six residues. Of the isolated proteinase inhibitors, the complete amino acid sequences of two major inhibitors were established by manual and automatic Edman degradations and standard enzymatic techniques. Each of the inhibitors, designated HHV inhibitor II and NNV inhibitor II, consisted of 57 amino acid with arginine and glycine at the NH2- and COOH-termini, respectively. Both contained six half-cystines in disulfide linkages, and their overall amino acid sequences were similar, showing 91% homology. The two inhibitors differed in sequence by only five amino acid replacements, Asp-3 to Arg; Tyr-17 to Arg; Leu-25 to Arg; Gln-32 to Glu; and Arg-52 to His, in the 57 residue peptide chain. Comparing the amino acid sequences of these two cobra venom inhibitors with those of Russell's viper venom inhibitor II and bovine pancreatic trypsin inhibitor (BPTI), about 50% homology was found in their sequences. The 6 half-cystinyl residues of these inhibitors were in the same linear positions. Moreover, the regions which are structurally and functionally important in the well-known BPTI molecule were found with extremely high sequence homology in the cobra venom inhibitors. These findings strongly suggest that the cobra venom inhibitors as well as Russell's viper inhibitor II have very similar conformations to that established for BPTI.
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PMID:Snake venom proteinase inhibitors. III. Isolation of five polypeptide inhibitors from the venoms of Hemachatus haemachatus (Ringhal's corbra) and Naja nivea (Cape cobra) and the complete amino acid sequences of two of them. 95 Mar 37

The interaction of hydrophobic probes, 8-anilinonaphthalene-1-sulfonate (ANS) and 4-benzoylamido-4'-aminostilbene-2, 2'-disulfonate (MBAS), with pig heart lipoamide dehydrogenase [NADH: lipoamide oxidoreductase, EC 1.6.4.3] was investigated. When ANS or MBAS was mixed with the apoenzyme of lipoamide dehydrogenase, the fluorescence quantum yield, of each dye was enhancedd markedly and the emission maxima concurrently shifted to the blue. The quantum yield, 0.038, of ANS bound to the apoenzyme, calculated from the corrected emission spectrum, was eight times higher than that in buffer solution, and the value, 0.0090, for bound MBAS was eighteen times higher than that in buffer solution. Moreover, the absortion bands of both ANS and MBAS shifted to the red upon binding with the apoenzyme. A general feature of the absorption spectra of these dyes observed on changing the solvent from polar to apolar was a red shift of the absorption bands. These results indicate that ANS or MBAS bound to the apoenzyme of lipoamide dehydrogenase is situated in a hydrophobic region of the apoenzyme molecule. It was found that 2 moles of each dye was bound per mole of the apoenzyme, which contains two polypeptide chains. The dissociation constants for the ANS- and MBAS-apoenzyme complexes were estimated to be 1.03X10(-5) and 1.54X10(-5) M, respectively. The enhanced fluorescence of both dyes bound to the apoenzyme decreased linearly upon adding FAD and disappeared at about 2 moles of FAD per mole of the apoenzyme. This suggests that both ANS and MBAS were displaced from their binding sites on the apoenzyme by FAD. The protein fluorescence spectrum of the apoenzyme had a maximum at 352 nm, which was blue-shifted by 6 nm from that of tryptophan in the buffer. Upon binding ANS or MBAS, the maximum of the protein fluorescence of the apoenzyme returned to 350 nm for the holoenzyme, and the fluorescence intensity decreased. Thus, the conformation around some tryptophan residues was affected by the binding of the dyes. When guanidine hydrochloride (GuHCl) was added to the ANS-apoenzyme complex solution, the enhanced fluorescence due to the bound ANS decreased and the emission maximum concurrently shifted to the red. Further, the maximum of the protein fluorescence of the apoenzyme shifted to the red, indicating the exposure of some tryptophan residues buried in an apolar region of the apoenzyme. Thus the binding of ANS to the apoenzyme was inhibited by protein denaturation due to GuHCL. In contrast, the holoenzyme of lipoamide dehydrogenase did not bind ANS or MBAS at all.
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PMID:Interaction of hydrophobic probes with the apoenzyme of pig heart lipoamide dehydrogenase. 95 45

The number of combining sites per mole of bovine colostral anti-DNP IgG2 was found to be 2 and the total affinity constant was 0.81 X 10(4) M-1. Unlike bovine colostral IgG1, the nonspecific binding of H3-epsilon-DNP-1-lysine by IgG2 as a function of increased concentrations, did not show a negative, cooperative slope. Spectral measurements made with anti-DNP IgG2 in the reference cell vs. anti-DNP IgG2 plus hapten in the experimental cell revealed a hypochromic, red shift from 363 to 365 nm. If the reference cell contained hapten, a red shift from 280 to 283 nm and an enhancement in the extinction coefficient of IgG2 was observed. These spectral changes were not observed if nonspecific IgG2 was substituted for anti-DNP IgG2 in the experimental cell. The enhancement in the extinction coefficient was interpreted to be due to a possible exposure of previously buried tryosine and tryptophan residues.
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PMID:Binding properties of bovine colostral anti-dinitrophenyl (dnp) immunoglobulins g2 (igg2). 99 4

A trypsin inhibitor was isolated as a homogenous protein from the seeds of guapuruvu-tree (Schizolobium parahyba (Vell.) Toledo). In addition to its strong inhibitory activity against trypsin the purified inhibitor presented a lesser activity against alpha-chymotrypsin. The purification of the protein inhibitor was achieved from the crude extract of deffated seeds through ammonium sulphate salting-out, successive chromatographies on Sephadex G-75 and DEAE-Sephadex A-50 columns followed by preparative polyacrylamide-slab electrophoresis. The following properties were presented by the purified inhibitor: molecular weight of 12,000 daltons, as estimated by gel filtration; isoelectric point at pH 5.0 - 5.2, by electrofocusing; combining molar ratio of 1:1 (mole trypsin/mole inhibitor), on the basis of inhibition assay and the molecular weight of 29,800 daltons found for the trypsin-inhibitor complex; A1%1-cm = 4.35, at 275 nm and pH 7.0. The inhibitor presents a high content of cystine (14 cystinyl residues per molecule) and is entirely devoid of methionine, tryptophan and free sulhydryl groups. The fluorescence spectra are typical for tyrosine with a strong quenching of emission indicated by the quantum yield. The circular dichroism spectra suggest a predominantly unordered structure for the inhibitor molecule.
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PMID:Isolation and some properties of a trypsin inhibitor from seeds of Schizolobium parahyba (Vell.) Toledo. 103 93

50-S ribosomal subunits from the extreme halophilic bacterium, Halobacterium cutirubrum, contain an alanine-rich acidic "A" protein which resembles the L7--L12 multimer (Kaltschmidt and Wittmann, 1970) found in the 50-S ribosomal subunit of Escherichia coli cells. The protein contains 24 mole % alanine and is devoid of histidine, tryptophan and cysteine. Unlike E. coli which has two forms of the "A" protein distinguished solely by the acetylation state of the serine amino terminus. H. cutirubrum 50-S subunits contain only one unsubstituted form of the "A" protein in vivo. However, during purification of ribosomes from cells grown between 25 and 37 degrees C the latter "A" protein undergoes rapid, specific, in vitro enzymatic alteration at its carboxy-terminal end. When the halophile is grown in the temperature range of 40 to 42 degrees C the cleaving enzyme is not active and only one form of the "A" protein is found on the ribosomes.
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PMID:Temperature related alterations in the acidic alanine-rich "A" protein from the 50S ribosomal particle of the extreme halophile, Halobacterium cutirubrum. 110 49

Low molecular weight components (g1, g2, and g3) were isolated from rabbit skeletal muscle myosin and their amino acid compositions were analyzed. One mole tryptophan was found in g1 and in g2, but none in g3. One mole of acetic acid was found per mole of each g-chain and it was concluded that the N-terminal groups of all three g-chains are acetylated. The minimum molecular weight of the g-chains were estimated from their amino acid compositions. It was estimated by SDS-disc electrophoresis that 1 mole of myosin contained 0.90, 1.7, and 0.63 moles of g1, g2, and g3, respectively. Similar values were obtained with psoas muscle myosin, but in heavy meromyosin prepared from skeletal muscle myosin the content of g2 was much lower, and that of g3 was much higher.
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PMID:Low molecular weight components (g-chains) of myosin from rabbit skeletal muscle. Separation, amino acid compositions and contents in myosin. 112 22

For anaerobic glucose-limited chemostat cultures of Aerobacter aerogenes a values of 14.0 g/mole was found for Ymax/ATP and a value of 6.8 mmoles ATP/g dry weight/hr for the maintenance coefficient. Both values are much lower than those previously determined for tryptophan-limited anaerobic chemostat cultures. It is concluded that generally the largest part of the maintenance energy is not used for true maintenance processes. For aerobic glucose-limited chemostat cultures two phases could be differentiated. Acetate production started at mu values higher than 0.53. The slopes of the curves relating the specific rates of glucose- and oxygen consumption with mu became higher and lower respectively above the mu value of 0.53. Using the YATP values obtained in the anaerobic experiment a P/O ratio of about 1.3 could be calculated for glucose- and tryptophan-limited chemostat cultures. In sulfate-limited chemostat cultures acetate was produced at all growth rates. At high growth rates also pyruvate and alpha-ketoglutarate were produced. With the YATP values obtained in the anaerobic experiment a P/O ratio of about 0.4 was calculated for sulfate-limited chemostat cultures.
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PMID:Determination of the efficiency of oxidative phosphorylation in continuous cultures of Aerobacter aerogenes. 115 84

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