Histidine In Solution Research Articles

Studies on the Effects of Amino-Acid on the Secretory Activity of the Gastric Peptic Cells and the Pancreatic Cells

10% solution or emulsion of amino acid, Alanine, Leucine, Methionine, Aspartic acid, Glutamic acid, Lysine, Arginine, Tyrosine, Histidine and Tryptophane, was injected into the stomach so that the effect of amino acid on the secretory activity of the gastric peptic cells and of the pancreatic cells might be proved.1. On the secretory activity of the gastric peptic cells, Methionine, Tyrosine, Histidine and Tryptophane are effective in various degree, the effects of the other amino acids are almost negligible. An effect can be seen without regard to pH value, or to number of amino-groups or acid-groups, or to the presence of S etc. of the solution or emulsion of amino acid.2. The effect on the peptic cells follows the discharge of the gastric hormone productin from the gastric surface cells, viz. the more active the amino acid in the secretion of productin the more promotive it is on the secretory function of the peptic cells.3. The most remarkable effect which exceeds others in degree can be seen in Histidine, an amino acid containing an imidazol group. The effect of Tyrosine and Tryptophane is low. This fact will be very interesting because an imidazol group has been previously proved to exist in the productin vacuoles of the gastric surface cells.4. On the production of zymogen granules in the pancreatic cells, the order was the same as that in the case of the discharge of productin, i. e. Histidine, Methionine, Tryptophane and Tyrosine.5. On the discharge of zymogen granules from the pancreatic cells, Tyrosine and Tryptophane are more effective than Histidine, and it is particularly noted that some of the amino acids which are almost negligible in their effect to the gastric peptic cells, display considerable activity in the discharge of zymogen granules. This activity can be detected in Alanine, Aspartic acid, Glutamic acid and Lysine. They may be active in the discharge of the duodenal hormone secretin though they are ineffectual in the discharge of the gastric hormone productin.

The formation of serotonin from 5-hydroxytryptophan after ultraviolet irradiation

UV.-irradiation of a 5-hydroxytryptophan solution results in formation of 5-hydroxytryptamine (serotonin) the yield being higher than that of histamine in a histidine solution under similar conditions. The possible importance of these findings, for biological effects of UV.-irradiation is discussed.

Some Remarks on the Determination of Histamine with Special Reference to Horse Blood

Summary.When treating histidine solutions according to BARSOTTM‐GADDUM‐CODB'S histamine extraction method it has been found that a small part of the histidine will be transformed into histamine. This is in accordance with the findings of ÅKERBLOM (1941).A simple method of extracting histamine from blood is described. To one volume of blood two volumes of ethyl alcohol is added together with H2SO4 sufficient to give the mixture a pH of about 4. The mixture is allowed to stand for 11/2 hour. After filtration and washing of the precipitate with alcohol the total filtrate is evaporated to a small volume in vacuo. After dilution with water and adjusting the pH to neutral the extract is ready for biological testing.Using this extraction method histamine was quantitatively recovered from water solutions of histamine and also from histamine added to horse blood.The amount of histamine in horse blood has been determined both according to CODE'S method and to the method described in this paper. Using CODE'S method a mean value of about 0.18 μg histamine per ml blood (expressed as dihydrochloride) was found whereas the other method gave a mean value of 0.065 μ per ml. Some part of the histamine obtained with CODE'S method may derive from the histidine in hemoglobin, decarboxylated during the extraction procedure. When extracting pure hemoglobin solutions according to CODE'S method the final extracts contain histamine in a concentration which corresponds to the above‐mentioned difference.

THE EFFECT OF AUXINS ON PROTOPLASMIC STREAMING. II

1. A further study has been made of the effect of indole-3-acetic acid (auxin) on protoplasmic streaming in the epidermal cells of the Avena coleoptile. 2. The transient nature of the effect of auxin, both in accelerating and retarding streaming, is due to the temporary exhaustion of carbohydrate from the tissues. In presence of 1 per cent fructose or some other sugars the acceleration or retardation of streaming by auxin is not transient, but is maintained for at least 2 hours. 3. The retardation of streaming brought about by concentrations of auxin above 0.5 mg. per liter is due to oxygen deficiency This has been confirmed in several ways. 4. It follows that the effect of auxin is to increase the respiration of the coleoptile tissue. 5. Younger coleoptiles, 3 cm. long, are sensitive to lower concentrations of auxin than those 5 cm. long, and more readily exhibit oxygen deficiency as a result of the action of auxin. However, after decapitation their response to auxin more closely resembles that of 5 cm. coleoptiles. 6. The retardation of streaming in such coleoptiles, resulting from oxygen deficiency, is delayed by very dilute solutions of histidine. On this basis an explanation is suggested for the results of Fitting on streaming in Vallisneria leaves. 7. The mean rate of streaming in control untreated coleoptiles in pure water varies with the time of year, but not with the time of day. 8. The results support the view that auxin accelerates an oxygen-consuming process which controls the rate of protoplasmic streaming, and that the latter controls growth. The substrate for this process is probably sugar. 9. It is suggested that auxin also accelerates another oxygen-consuming process, which may withdraw oxygen from the process which controls streaming rate and hence cause retardation of the latter.

The Estimation of Histidine

The estimation of arginine, histidine and lysine in small amounts of protein by the silver precipitation method has been satisfactorily employed by Miller, Mazur, Plimmer, and others. However, Abderhalden and Siebel were only successful in the determination of arginine and lysine. The latter investigators reported large losses of histidine during the purification procedures in which HgSO4 and CuCO3 are employed. It has been recognized that histidine is the most difficult of the basic amino acids to determine accurately and we take this occasion to present some details of the modifications of the 1934 procedure. Histidine is precipitated from the protein hydrolysate at pH 7.4 with AgNO3 and Ba(OH)2. The precipitate is centrifuged, washed and decomposed with H2S after suspending in dilute H2SO4 (cf. for apparatus). The Ag2S is removed and the filtrate and washings are concentrated in vacuo (cf.). The filtrate is adjusted to pH 3.5-4.5 with Ba(OH)2, and after removal of the BaSO4, the histidine solution is concentrated to approximately 20 cc. and decolorized with charcoal. The precipitate is filtered, thoroughly washed with hot H2O and the filtrate is diluted to volume (100 cc). Histidine may be determined directly as follows. (a) Colorimetric (Kapeller-Adler). 2 cc. portions (containing 0.5-1.0 mg. of histidine per cc.) of the sparkling histidine sulfate solution are pipetted into 6 test tubes graduated at 10 cc. Into 6 other similar tubes, an equal quantity of histidine standard is placed. (For best results, standard and unknown should contain approximately the same amounts of histidine.) The 12 tubes are set up alternately and an excess of Br2 in dilute acetic acid (cf.) is added. The bromination is allowed to proceed for 10 minutes, care being observed that all the solutions are colored yellow at the end of this period. The excess Br2 is removed by a drop of As2 O3, and 2 cc. of NH4 0H reagent (cf.) per tube are added immediately. The contents of the tubes are mixed and they are placed in mildly boiling H2O for 5 minutes. At the end of this period, the solutions are cooled in ice for 10 minutes and diluted to volume with NH4OH reagent. The contents of each group of test tubes are mixed and the colors matched in the usual fashion. (b) Gravimetric (nitranilic acid). In 1936, Town claimed that nitranilic acid (2,5-dihydroxy-3,6-dinitroquinone) specifically precipitates glycine from an ethanolic solution of the products of protein Itydrolysis. Stein found that the amount of glycine in gelatin estimated by Town's method was greater than that determined by Bergmann and Fox and that this discrepancy could be explained by the partial precipitation of the basic amino acids along with glycine. We have found that nitranilic acid can be used successfully for the isolation of histidine as follows: The remainder of the histidine solution (cf. a) is concentrated in vacuo (pH 3.5-4.0) and an excess of nitranilic acid (freshly dissolved) in H2 O, (CH3)2 CO, or CH3 OH is added. The finely crystalline, yellow precipitate is filtered off, washed and dried at 110°. The gravimetric and colorimetric estimations check very closely, on analysis of 15 brain proteins, if the factor 0.403 × the weight of the yellow precipitate is employed. Further work along this line is now in progress. In certain instances, further purification of the histidine fraction is desirable before estimation of the amino acid. In such cases, the histidine sulfate solution is concentrated to approximately 120 cc. and an excess of Denige's reagent (cf.) is added. The suspension is centrifuged for 20-30 minutes and the filtrate is discarded. The precipitate is suspended in H2O and decomposed with H2S. After removal of the HgS and H2S, the histidine solution is adjusted to pH 5-6 with Ba(OH)2. BaSO4 is removed and washed. The filtrate is boiled and it is made alkaline to litmus by the addition of minimal quantities of BaCO3. An excess of CuSO4 Results indicating the probable errors of the method, which are based on more than 10 experiments, each starting with 0.1355 gm. of histidine hydrochloride hydrate are given: