Effect of tryptophan excess in a diet on amino acid composition of skin collagen and on an initial stage of protein biosynthesis in rat liver

Protein deficiency and tryptophane load against its background lead to the acid-soluble collagen synthesis in the rat skin. The amino acid composition of the collagen differs from the norm. This is accompanied by changes in the free amino acid pool of blood serum and liver, under tryptophane load the free amino acids pool of the liver increasing twice as high. At the same time protein deficiency increases and tryptophane load decreases the level of tRNA amino acylation with tryptophane in the animal liver. Thus, protein deficiency and tryptophane load against its background cause deep changes in the protein biosynthesis.     

The humification of high-moor peat

Summary It has been observed that dark coloured substances are formed by soil micro-organisms (Pseudomonas, Arthrobacter-Corynebacterium-Nocardia group, spore forming bacteria and Streptomyces) from aromatic compounds,e.g. phenol, benzoic acid, guaiacol, toluene, phthalic acid, catechol, tyrosine, and tryptophane. The dark-brown to black substances formed by these organisms possess humus-like qualities and have the appearance of dopplerite. Reducing substances reacting in the cold with triphenyl tetrazolium chloride are formed as intermediates. It is suggested that these intermediary substances are quinones, or semiquinones and that these occur as free radicals which subsequently polymerize to humus-like substances.     

Repression of the synthesis and allosteric inhibition of 3-deoxy-D-arabinoheptulosonate-7-phosphate synthase in facultative methylotrophic bacterium Pseudomonas sp. M

The synthesis of 3-deoxy-D-arabinoheptulosonate-7-phosphate-synthase has been shown to be repressed by tyrosine and phenylalanine in the cells of facultative methylotrophic bacteria Pseudomonas sp. M. Activity of the enzyme is subjected to allosteric inhibition by tyrosine, tryptophane, anthranylate and phenylpyruvate.     

Localization of antigenic determinants on a molecule of trophoblast-specific beta 1-glycoprotein

Spatial localization of antigenic determinants of trophoblast-specific beta I-glycoprotein (TSG) has been elucidated using chemical modifications of the sugar and protein moieties of the molecule. Various deglycosylation procedures of TSG afforded fragments slightly soluble even in the presence of powerful detergents. Treatment of TSG with boric acid and its salts, accompanied with a conformational change of the sugar moiety, failed to alter conformation of the protein portion as evidenced by CD spectral data. This modification was found to increase the antigenic activity of TSG only scarcely. Modification of tryptophane or tyrosine residues of TSG changed spatial structure of the protein portion to can be a considerable loss of the TSG antigenic activity. The data obtained led to the conclusion that antigenic determinants of TSG are localized at the protein portion of the molecule and are topographic. A tryptophane residue is an indispensable constituent of the antigenic determinants.     

DETERMINATION OF CERTAIN AMINO ACIDS IN CHYMOTRYPSINOGEN,AND ITS MOLECULAR WEIGHT

1. A preparation of chymotrypsinogen, obtained from Dr. M. Kunitz, was analyzed for sulfur, the sulfur amino acids, tyrosine, and tryptophane. 2. The protein sulfur of chymotrypsinogen was accounted for as methionine, cysteine, and cystine. 3. A method is presented for calculating the minimum molecular weight of a protein from the distribution of the sulfur amino acids. In the case of chymotrypsinogen, the calculated minimum molecular weight was found to be the actual molecular weight. 4. The molecular weight of chymotrypsinogen is 36,700 by amino acid analysis as compared to 36,000 by osmotic pressure measurements of Kunitz and Northrop. Chymotrypsinogen contains per mol 17 atoms of sulfur, 3 residues of methionine, 4 of cysteine, 10 of half-cystine (i.e. 5 S—S linkages), 6 of tyrosine, and 10 of tryptophane. 5. The tryptophane content of chymotrypsinogen (5.51 per cent) is the highest of any protein so far on record. 6. Chymotrypsinogen contains no reactive SH groups, although it yields cysteine on hydrolysis. This may be due either to preformed but unreactive SH groups or to S—X groups. The term S—X group is used to denote the substitution of the sulfhydryl hydrogen by a constituent X; hydrolysis yields SH groups: S—X + HOH = SH + X—OH.     

Histochemistry of lower vertebrate calcified structures. I. Enamel of the dogfish Squalus acanthius compared with mammalian enamel and homologous dentine

The enameloid and dentine of Squalus acanthius have been compared histochemically with those of Bos taurus. Squalus enameloid is much less reactive to a variety of stains or reagents than dentine or bovine immature enamel but it does have positive reactions with picromethyl blue, Mallory's and Van Gieson's stains, and Alcian blue. It stains faintly with Biebrich scarlet, indicating some anionic groups. Specific reactions for tyrosine, tryptophane, lysine, histidine, arginine, and cysteine are negative. Bos immature enamel is positive for cationic, anionic, and aromatic reactive groups by all test procedures, and dentine was positive for the anionic components. Bovine maturing enamel, however, is more similar in terms of lack of reactivity to Squalus enameloid but differed because the bovine enamel was moderately positive for tyrosine; tryptophane, and anionic groups and negative with Mallory's picromethyl blue and Van Gieson's stains. A fibrous transitional area between Squalus dentine and enameloid has staining reactions characteristic of both collagen and keratins.     

ELECTROPHORETIC HOMOGENEITY OF PREGNANT MARE SERUM GONADOTROPHIN

A highly purified and potent gonadotrophin in pregnant mare serum has been prepared. The preparation has been shown to be electrophoretically homogeneous in the Tiselius apparatus. The mobilities of the substance have been determined over a wide range of hydrogen ion concentrations. The isoelectric point lies at pH 2.60–2.65 and the value of See PDF for Equation is 4.0 x 10^–5. Some chemical constituents have been studied. From the tryptophane and tyrosine content the molecular weight of the hormone is estimated to be 30,000. The hormone has been subjected to acetylation by ketene in aqueous solution at room temperature and the result suggests again the essentiality of free amino groups for the biological activity of the hormone. In this respect it is to be contrasted with human chorionic gonadotrophin.     

Selective photooxidation of methionine, tyrosine and tryptophane using thionine and toluidine blue as sensitizers (author's transl)

Thionine and toluidine blue were used as sentizers on photooxidation processes of methionine, tryosine and tryptophane. They were more effective than methylene blue. Methionine was photooxidized to sulfoxide and tryptophane to kinurenine. A tyrosine-sensitizer addition compound was postulated. Dye concentration, pH, temperature and EDTA presence conditions were determined on each one of the modification reactions. Methionine at acid pH was selectively modified. On the basis of obtained results and published references, a direct interaction of singlet oxygen with methionine and tryptophase and the excited dye with tyrosine was respectively discussed.     

Single-channel studies on linear gramicidins with altered amino acid sequences. A comparison of phenylalanine, tryptophane, and tyrosine substitutions at positions 1 and 11

The relation between chemical structure and permeability characteristics of transmembrane channels has been investigated with the linear gramicidins (A, B, and C), where the amino acid at position 1 was chemically replaced by phenylalanine, tryptophane or tyrosine. The purity of most of the compounds was estimated to be greater than 99.99%. The modifications resulted in a wide range of conductance changes in NaCl solutions: sixfold from tryptophane gramicidin A to tyrosine gramicidin B. The conductance changes induced by a given amino acid substitution at position 1 are not the same as at position 11. The only important change in the Na+ affinity was observed when the first amino acid was tyrosine. No major conformational changes of the polypeptide backbone structure could be detected on the basis of experiments with mixtures of different analogues and valine gramicidin A (except possibly with tyrosine at position 1), as all the compounds investigated could form hybrid channels with valine gramicidin A. The side chains are not in direct contact with the permeating ions. The results were therefore interpreted in terms of modifications of the energy profile for ion movement through the channel, possibly due to an electrostatic interaction between the dipoles of the side chains and ions in the channel.     

Dark and light metabolism of amino acids inChlorella vulgaris

An investigation was made of the suitability of 27 amino acids to serve as source of nitrogen, carbon and energy forChlorella vulgaris in the dark. Only leucine led to profuse growth. Eight other amino acids were moderately effective.In the light, almost all of the amino acids tested proved to be suitable nitrogen sources. Histidine and tryptophane, however, damaged the cells and killed them after a few weeks cultivation in the light, the cultures turning black with histidine and brown with tryptophane. The effect of histidine could be abolished by including pyridoxine or nicotinamide in the culture medium.     

Amino acid requirements for attachment and outgrowth of the mouse blastocyst in vitro

Arginine, cystine, histidine, leucine and threonine were needed for outgrowth of the mouse blastocyst in vitro. Omission of lysine, methionine, phenylalanine, tryptophane and tyrosine from the culture medium markedly reduced blastocyst outgrowth, but did not inhibit it completely; while omission of isolecine and valine reduced the extent of outgrowth only slightly. Blastocysts kept for seven days in a free-floating condition by omitting arginine and leucine from the medium, grew out when these amino acids were added. Such behavior may be analogous to delayed implantation in utero and suggests that the free amino acid content of the uterus could be an important factor in the control of implantation. Blastocysts delayed from implanting in the uterus by ovariectomy were activated to outgrowth in a complete medium, but the intracellular changes associated with outgrowth occurred more slowly than in undelayed blastocysts.     

Effect of tryptophan and its metabolites on the conditioned reflex activity of the honeybee

The effect of tryptophane and its derivatives on the rate of elaboration and transformation of conditioned reflexes (CR) to odour, with alimentary reinforcement, was studied in wild bees under two conditions: free movement of the bee or its immobilization (stress situation), by means of genetic models (mutations, successive blocking stages of kynurenin path of tryptophane metabolism). It was shown that mutations eliciting accumulation of free tryptophane and serotonin in the hemolymph of the bees and creating a deficit of kynurenins accelerate the transformation of conditioned reflexes and aggravate the depression of conditioned activity usually elicited in wild bees by monotonous prolonged presentation of conditioned signal. The injections of tryptophane and serotonin (5 mg) produce the same action. Mutations, eliciting accumulation in the hemolymph of the kynurenins (kynurenin and 3-hydroxikynurenin) accelerate, in conditions of immobilization, the formation of conditioned reflexes and delay the process of their transformation, and also contribute to maintainance of a higher (in comparison with the norm) level of the conditioned activity under monotonous presentation of the signal. The same action is produced by the injection of 1 mcg kynurenin.     

Regulation of the activity and synthesis of 3-deoxy-D-arabinoheptuloso-7-phosphate synthase in the obligate methylotroph Methylobacillus flagellatum KT]

The activity of the first enzyme of aromatic path 3-deoxy-D-arabino-heptuloso-7-phosphate-synthase (DAHP-synthase) is regulated by retro-inhibition and is a subject of repression. Analysis of partially purified preparations of the enzyme has revealed three isoenzymes: DAHP-synthase-Tyr, DAHP-synthase-Trp and DAHP-synthase-Phe, each of them being regulated by a corresponding amino acid. DAHP-synthase-Phe is a dominant isoenzyme presenting 70% of the enzyme activity, 30% inhibition of which is possible by 7.0 mkM of phenylalanine. DAHP-synthase-Tyr and DAHP-synthase-Trp are minor isoenzymes (sharing 15% of enzyme activity each) and are controlled by tyrosine and tryptophane correspondingly. 50% of inhibition of activity is possible by adding 0.7 and 0.8 mkM of corresponding amino acid. Regulation of the enzyme synthesis was studied in the Trp-, Phe- and Tyr- mutants. The enzyme activity was registered under the conditions of limiting and surplus of each aromatic amino acid. The synthesis of DAHP-synthase in M. flagellatum KT is repressed by tryptophane and tyrosine decreasing the synthesis 18.8 and 15.6 fold.     

Amino acid decarboxylases in some fungi

The authors describe a method for the determination of decarboxylase activity in fungi. Some of the strains of test fungi (Stachybotrys alternans, Fusarium andAspergillus) displayed arginine, lysine, phenylalanine, asparaginic and glutamic decarboxylase activity. No tyrosine, tryptophane, histidine or ornithine decarboxylase activity was found. Some of the factors influencing the activity of these enzymes are discussed.     

Effect of calcium binding on the quenching time of self-fluorescence of Ca-binding proteins

Lifetimes of phenylalanine, tyrosine and tryptophan self-fluorescence of three Ca2+-binding proteins (parvalbumins pI 4.47 and 3.95 and bovine alpha-lactalbumin) in the Ca2+-saturated state and without Ca2+ were measured on a device functioning in a channel of synchrotron radiation of the Lebedev Physical Institute electron accelerator C-60 with a single photon counting system. The decay curve of phenylalanine fluorescence of Ca2+-saturated parvalbumin pI 4.47 is two-exponential, which results from the presence of two subsystems of phenylalanine residues in this protein. Radiation of these subsystems is almost independent of one another. Detachment of Ca2+ from protein disturbs these subsystems. In case of tyrosine fluorescence of carp parvalbumin pI 3.95 a change in the quantum yield value of the stationary fluorescence induced by elimination of Ca2+ proceeds without a change of fluorescence lifetime. This seems to be related to the existence of static quenching of fluorescence in this case at the expense of complex formation between the chromophore and some adjacent quenching groups. Detachment of Ca2+ from alpha-lactalbumin induces conformational changes in its structure. The latter result in a transition of a number of tryptophane residues from its interior to the surface of the globule which is reflected in an increase of fluorescence quantum yield duration. It is concluded that in Ca2+-saturated alpha-lactalbumin some tryptophane residues are located near the quenching groups (dynamic quenching), most likely the disulfide bridges.     

嗜甲基菌DM11菌株二氯甲烷脱卤素酶基因的定点诱变

为了研究嗜甲基菌（Methylophilus）DM11菌株二氯甲烷脱卤素酶的不同氨基酸残基在底物结合、谷胱甘肽（GSH）亲和以及催化活力中的作用,对编码该酶的基因进行了定点诱变研究。将保守的103位色氨酸（W）分别用苯丙氨酸（F）、缬氨酸（V）或天冬酞胺（N）替换,109位精氨酸（R）用亮氨酸（L）替换,117位色氨酸用酪氨酸（Y）或苯丙氨酸替换,得到6种突变酶。其中3种突变酶具有较低的活力,另外3种突变酶没有活力。突变酶W117Y的性质与野生型酶明显不同。     

Rhipicephalus sanguineus: amino acid composition of egg shell

Acid hydrolysis of the protein fraction of a batch of egg shells of Rhipicephalus sanguineus was followed by determination of the amino acids in the hydrolysate. Using thin layer chromatography, the amino acids—lysine, arginine, aspartic acid, serine, glycine, glutamic acid, alanine, threonine, valine, tyrosine, isoleucine, and leucine were identified. Alkaline hydrolysis of the fraction followed by TLC revealed the presence of tryptophane. Chitin was revealed utilizing a chitosan test.     

THE REACTIONS OF IODINE AND IODOACETAMIDE WITH NATIVE EGG ALBUMIN

The following experimental results have been obtained. 1. Native egg albumin treated with iodine and then denatured no longer gives a nitroprusside test or reduces dilute ferricyanide in neutral Duponol PC solution. 2. More iodine is needed to abolish the ferricyanide reduction if the reaction between native egg albumin and iodine is carried out at pH 6.8 than if the reaction is carried out at pH 3.2. At pH 6.8 iodine reacts with tyrosine as well as with cysteine. 3. Cysteine and tryptophane are the only amino acids with reducing groups which are known to react with dilute iodine at pH 3.2 The reducing power of cysteine is abolished by the reaction with iodine, whereas the reducing power of tryptophane remains intact. Pepsin and chymotrypsinogen which contain tryptophane but not cysteine, do not react at all with dilute iodine at pH 3.2. 4. Native egg albumin treated with iodoacetamide at pH 9.0 and then denatured by Duponol PC reduces only 60 per cent as much dilute ferricyanide as egg albumin which has not been treated with iodoacetamide. 5. The SH group is the only protein reducing group which is known to react with iodoacetamide. The simplest explanation of the new observation that the SH groups of egg albumin can be modified by reactions with the native form of the protein is that the native egg albumin has free and accessible but relatively unreactive SH groups which can react with iodine and iodoacetamide despite the fact that they do not react with ferricyanide, porphyrindin, or nitroprusside. Preliminary experiments suggested by the results with egg albumin indicate that the tobacco mosaic virus is modified by iodine at pH 2.8 without being inactivated and that the tobacco mosaic and rabbit papilloma viruses are not inactivated by iodoacetamide at pH 8.0.     

Inhibition of invitro sickling by liposome-mediated transport of amino acids into intact human red blood cells

To investigate the role of phenylalanine and tryptophane as potential antisickling agents in intact human SS-red blood cells a liposomal transport system was employed to transfer phenyl-alanine or tryptophane into intact SS-red blood cells. Aromatic amino acids and short peptides containing phenylalanine have been demonstrated to increase the minimum gelling concentration and solubility of deoxy-hemoglobin S in aqueous solution. However, these compounds do not cross the red blood cell membrane under usual incubation conditions. Incorporation of phenylalanine or tryptophane into intact SS-red blood cells $\text{via}$ liposomal transport system markedly inhibited the $\text{in}\text{vitro}$ sickling of deoxy-hemoglobin S. These findings raise the possibility that a nontoxic liposomal transport system which facilitates incorporation of antisickling agents into intact SS-RBC may have significant therapeutic implications in the treatment of sickle cell disease.     

The importance of dietary amino acids on the reproduction and longevity of adult Dacus oleae (Gmelin) (Diptera Tephritidae)

When the amino-acid mixture of an effective chemically defined diet was replaced by single amino acids, keeping the total nitrogen at the same level, the egg production of Dacus oleae was minimal with all the 19 amino acids tested. Male survival was adversely affected by the amino acids : alanine, aspartic acid, glutamic acid, glycine, hydroxyproline, lysine, serine and tyrosine, while female survival was shortened when the amino acids : glycine, hydroxyproline and lysine were added. The creation of amino-acid imbalances, by deleting the 19 amino acids individually, from the complete amino-acid mixture, showed that the amino acids : arginine, histidine, isoleucine, leucine, lysine, methionine, phenylalanine, serine, threonine, tryptophane and valine were indispensable to the adult Dacus oleae flies, as far as egg production is concerned. Survival of the male flies was significantly shortened when the amino acids : alanine, hydroxyproline and tryptophane were omitted. Significant differences in longevity between males and females were scored, when the amino acids : alanine, aspartic acid, cystine, glycine and tryptophane, were omitted.