scholarly journals Studies on enzyme action. XIII.—Enzymes of the type

1910 ◽  
Vol 82 (556) ◽  
pp. 349-367 ◽  
Keyword(s):  
Hydrogen Cyanide ◽  
Specific Enzyme ◽  
Enzyme Action ◽  
Milk Sugar ◽  
Previous Communication

In the previous communication of this series (No. XII, 1908, B, Vol. 80, pp. 321—329) the contention was advanced that “emulsin’’prepared from sweet almonds contains at least three distinct enzymes, viz., amygdalase , a β-glucase and gluco-lactase : the first of these, amygdalase, being the enzyme by which amygdalin is resolved into glucose and Fisclier’s glucoside, β -glucase that by which β -glucosides are hydrolysed, gluco-lactase that which hydrolyses milk sugar. Meanwhile the striking discovery has been made by Rosenthaler that emulsin has the property of inducing the formation of dextro-rotatory benzylidenecyanhydrol—such as may be obtained from amygdalin—from benzaldehyde and hydrogen cyanide; this raises the question whether there may not also be present in “emulsin” a specific enzyme capable of operating on the cyanophoric radicle of amygdalin and of resolving it into hydrogen cyanide and benzaldehyde. To avoid periphrasis this hypothetical enzyme may be spoken of as benzcyancise.

scholarly journals Studies on enzyme action. XI.-Hydrolysis of raffinose by acids and enzymes

1908 ◽  
Vol 80 (540) ◽  
pp. 312-321 ◽  
Keyword(s):  
Cane Sugar ◽  
Point Of View ◽  
Enzyme Action ◽  
Milk Sugar ◽  
Previous Communication ◽  
Specific Behaviour ◽  
Hydrolysis Of

In a previous communication of this series (vol. 74, p. 191), it is pointed out that the various glucosides are hydrolysed by acids at very different rates, the relative values being approximately of the order shown in the following table:- α -Methylglucoside....100 β -Methylglucoside....180 α -Methylglucoside....540 β -Methylglucoside....880 Salicin ( a β -glucoside)....600 Milk-sugar ( α β -galactoside)....720 Maltose (an α -glucoside)....740 Cane-sugar, it is to be remembered, is hydrolysed at a rate vastly more rapid-at least 1000 times as rapidly as maltose, in fact. These differences, taking into account the peculiar specific behaviour of enzymes as hydrolytic agents, raise questions of interest from the chemical side and they are of no slight significance perhaps also from a biological point of view.

scholarly journals Studies on enzyme action. IV.—The sucroclastic action of acids as contrasted with that of enzymes.

1904 ◽  
Vol 73 (488-496) ◽  
pp. 526-537 ◽  
Author(s):  
Edward Frankland Armstrong ◽  
Robert John Caldwell ◽  
Henry Edward Armstrong
Keyword(s):  
Cane Sugar ◽  
Enzyme Action ◽  
Milk Sugar ◽  
New Instrument ◽  
Hydrolysis Of

Not only are the various bioses hydrolysed at very different rates by enzymes but they are also known to differ in their behaviour towards acids: cane sugar being hydrolysed with the greatest facility, whilst maltose is acted upon but slowly. The experiments described in this communication were instituted primarily with the object of ascertaining the behaviour of milk sugar, of which nothing was known. The hydrolysis of cane sugar under the influence of acid was carefully investigated by Wilhelmy as far back as 1850, with the aid of the polariscope, then a new instrument.

Food for Thought: Enzyme Action

Reactions ◽  
2011 ◽  
Author(s):  
Peter Atkins
Keyword(s):  
Cell Wall ◽  
Specific Enzyme ◽  
Complex Molecules ◽  
Enzyme Action ◽  
Target Molecule ◽  
Fatal Bleeding ◽  
To Come ◽  
Enzyme Molecules ◽  
Essential Contribution ◽  
Chymotrypsin A

Nature makes use of the tools that I have been developing, and does so in the most extraordinary and subtle manner. After all, she has had about four billion years to come up with solutions to problems with which human chemists have striven seriously for only a century or so. Most of the reactions that go on in organisms—including you—are controlled by the proteins called ‘enzymes’ (a name derived from the Greek words for ‘in leaven’, as in yeast). Enzymes are biological catalysts (Reaction 11) that are extraordinarily specific and highly effective in their role. One of these complex molecules might serve as the merest foot soldier in the army of reactions going on inside you, with a role such as severing the bond between two specific groups of atoms in a target molecule. Because their function may be highly specific, enzyme molecules need to be large: they have to recognize the molecule they act on, act on it, then release it so that they can act again. Thus, they have to have several functions built into them. As you will see, enzymes are the ultimate in functional blindness: they feel around in their surroundings in order to identify their substrate, the species they can act on. Life is ultimately blind chemical progress guided by touch. I am going to introduce you to one particular group of enzymes, the ‘proteases’, and focus on one example from this group, namely chymotrypsin. A protease is a traitor to its kind: it is a protein that breaks down other proteins. It plays a role in digestion, of course, but its range is much wider. One protease enables a lucky sperm to eat through the cell wall of an egg and ensure its at least temporary immortality. Another facilitates the clotting of blood to terminate possibly fatal bleeding. Chymotrypsin itself is an enzyme that is secreted from the pancreas into the intestine, and makes an essential contribution to the process of digestion. Its name is derived slightly circuitously from the Greek words for animal fluid, a bodily ‘humour’, and rubbing, as it was obtained as a fluid by rubbing the pancreas.

scholarly journals Studies on enzyme action. XII.-The enzymes of emulsin

1908 ◽  
Vol 80 (540) ◽  
pp. 321-331 ◽  
Keyword(s):  
Aspergillus Niger ◽  
Small Proportion ◽  
Enzyme Action ◽  
Milk Sugar ◽  
The Subject ◽  
Made In

Emulsin has frequently been the subject of discussion in this series of studies: thus the rate at which it hydrolyses milk-sugar was considered in No. II (Vol. 73, pp. 507, 515) and its action contrasted with that of Kephirlactase, which was shown to act more rapidly than emulsin. In No. III (vol. 73, p. 518) it was pointed out that whilst Kephir-lactase is controlled by galactose and scarcely at all by galactose. These conclusions were confirmed by experiment with the methyl-glucosides and galactosides (p.523). In No. V (Vol. 74, p. 188) the question was discussed whether emulsin proper hydrolyses milk-sugar or whether, as Bourquelot and Hérissey have contended, emulsin contains a small proportion of lactase: against this assumption it was argued that the curve was not of the form to be expected if only a small quantity of lactase were present; that whereas Kephir-lactase was controlled by galactose alone, emulsin was most retarded by glucose and only to a slight extent by galactose, also that the curves for emulsin differed in character from those for lactase. Attention was directed, however, to Pottevin’s statement that Aspergillus niger contains an enzyme capable of hydrolysing β -glucosides, but not β -galactosides nor milk-sugar. In No.X (B, vol. 79, p. 360) some of the statements made in earlier studies were rectified and it was announced that evidence had been obtained, to the presence of a distinct enzyme capable of hydrolysing only β -glucosides. While admitting this to be the case, however, we may point out that the conclusions we have to bring forward involve merely a different reading of the facts: the facts have been correctly advanced on both sides.

scholarly journals Studies on enzyme action. XIX.—Urease: a selective enzyme. II.—Observations on accelerative and inhibitive agents

1913 ◽  
Vol 86 (588) ◽  
pp. 328-343 ◽  
Keyword(s):  
Carbonic Acid ◽  
Early Date ◽  
Enzyme Action ◽  
Previous Communication ◽  
General Outcome ◽  
New Situation ◽  
Remarkable Manner

In the previous communication experiments were described which had been made with the Urease present in the Soja bean proving that the enzyme is strictly selective in its action and that whilst its activity is much reduced by ammonia it is increased, in a remarkable manner, by the presence of carbonic acid: in other words, the two products of change affect the activity of the enzyme in opposite ways—a result altogether without precedent. In explanation of these results, the suggestion was made that Urease is a feebly acidic substance. Though it was obvious that the results were not to be harmonised with the views that were current as to the manner in which enzymes act, we refrained from comment, deeming it desirable to obtain more information before discussing the new situation that was created. In the interval, the behaviour of other enzymes has been under observation by Dr. E. F. Armstrong and ourselves and it is proposed to discuss the general outcome of the work, in a comprehensive communication, at an early date. Meanwhile, we desire to bring forward an account of further observations on Urease carried out with the object of ascertaining the manner in which the activity of the enzyme is affected by the presence of various substances together with the urea.

Abspaltung chemischer Komponenten der Coli-Membran durch daran adsorbierte Phage

1956 ◽  
Vol 11 (6) ◽  
pp. 345-353 ◽  
Author(s):  
G. Koch ◽  
W. Weidel
Keyword(s):  
Cell Membrane ◽  
Host Cell ◽  
Specific Enzyme ◽  
Host Cell Membrane ◽  
Enzyme Action ◽  
Yellow Color

Evidence is brought forth that certain bacteriophages (T2, T4) carry a specific enzyme at their tailtips. It splits chemically defined material off the host cell membrane to which the virus is adsorbed. The splitting reaction can be followed directly and quantitatively by using membranes as a „substrate“ which have been treated with dinitro-fluorobenzene. Dinitrophenyl-residues attached to amino- and other groups of the membrane do not inhibit adsorption and splitting, and splitting-products can be measured colorimetrically on account of their yellow color which also facilitates their isolation. By these means the enzyme action which might be a prerequisite to infection, has been studied to some extent.

scholarly journals Studies on enzyme action. XXII.--Lipase (IV)-The correlation of synthetic and hydrolytic activity

1914 ◽  
Vol 88 (601) ◽  
pp. 176-189 ◽  
Keyword(s):  
Thin Film ◽  
Aqueous Solution ◽  
Fatty Acids ◽  
Comparative Study ◽  
Hydrolytic Activity ◽  
Mass Action ◽  
Enzyme Action ◽  
Previous Communication ◽  
Hydrolysis Of ◽  
Higher Fatty Acids

In the previous communication on this subject, in which the behaviour of Lipase towards ethereal salts generally was discussed, it has been argued that the enzyme is specially fitted to determine the hydrolysis of the insoluble, oily, glyceric salts of the higher fatty acids but is not suited to act in aqueous solution : we expressed the opinion that interaction must be supposed to take place at between surfaces separated only by a thin film of water at most-in other words, that water in excess is inimical to the occurrence of change. The results we advanced, in conjunction with those deduced from the study of other enzymes, notably urease, also led us to conclude that it is impossible to apply the laws of mass action directly to the interpretation of the causes effected by Lipase. Previously we have directed our attention only to the hydrolytic activity of the enzyme : numerous observation are on record which prove that, whether of animal or vegetable origin, it can act reversibly but no comparative study of the two processes has been made hitherto in the case of facts.

Hydrogen Cyanide Polymers from the Impact of Comet P/Shoemaker-Levy 9 on Jupiter

1997 ◽  
Vol 161 ◽  
pp. 179-187
Author(s):  
Clifford N. Matthews ◽  
Rose A. Pesce-Rodriguez ◽  
Shirley A. Liebman
Keyword(s):  
Amino Acids ◽  
Solar System ◽  
Hydrogen Cyanide ◽  
Nitrogen Heterocycles ◽  
Laboratory Studies ◽  
Heterogeneous Solids ◽  
The Many ◽  
Comet Halley ◽  
The Impact ◽  
By Products

AbstractHydrogen cyanide polymers – heterogeneous solids ranging in color from yellow to orange to brown to black – may be among the organic macromolecules most readily formed within the Solar System. The non-volatile black crust of comet Halley, for example, as well as the extensive orangebrown streaks in the atmosphere of Jupiter, might consist largely of such polymers synthesized from HCN formed by photolysis of methane and ammonia, the color observed depending on the concentration of HCN involved. Laboratory studies of these ubiquitous compounds point to the presence of polyamidine structures synthesized directly from hydrogen cyanide. These would be converted by water to polypeptides which can be further hydrolyzed to α-amino acids. Black polymers and multimers with conjugated ladder structures derived from HCN could also be formed and might well be the source of the many nitrogen heterocycles, adenine included, observed after pyrolysis. The dark brown color arising from the impacts of comet P/Shoemaker-Levy 9 on Jupiter might therefore be mainly caused by the presence of HCN polymers, whether originally present, deposited by the impactor or synthesized directly from HCN. Spectroscopic detection of these predicted macromolecules and their hydrolytic and pyrolytic by-products would strengthen significantly the hypothesis that cyanide polymerization is a preferred pathway for prebiotic and extraterrestrial chemistry.

Further Ultrastructural Observations on Metastatic Nodules of Human Breast Cancer

1968 ◽  
Vol 26 ◽  
pp. 224-225
Author(s):  
John L. Swedo ◽  
R. W. Talley ◽  
John H. L. Watson
Keyword(s):  
Breast Cancer ◽  
Human Breast Cancer ◽  
Estrogen Therapy ◽  
Specimen Preparation ◽  
Human Breast ◽  
Autophagic Vacuoles ◽  
Previous Communication ◽  
Linear Profiles ◽  
Metastatic Nodule

Since the report, which described the ultrastructure of a metastatic nodule of human breast cancer after estrogen therapy, additional ultrastructural observations, including some which are correlative with pertinent findings in the literature concerning mycoplasmas, have been recorded concerning the same subject. Specimen preparation was identical to that in.The mitochondria possessed few cristae, and were deteriorated and vacuolated. They often contained particulates and fibrous structures, sometimes arranged in spindle-shaped bundles, Fig. 1. Another apparent aberration was the occurrence, Fig. 2 (arrows) of linear profiles of what seems to be SER, which lie between layers of RER, and are often recognizably continuous with them.It was noted that the structure of the round bodies, interpreted as within autophagic vacuoles in the previous communication, and of vesicular bodies, described morphologically closely resembled those of some mycoplasmas. Specifically, they simulated or reflected the various stages of replication reported for mycoplasmas grown on solid nutrient. Based on this observation, they are referred to here as “mycoplasma-like” structures, in anticipation of confirmatory evidence from investigations now in progress.

Rotational spectrum and properties of a complex of hydrogen cyanide and chlorine monofluoride

1996 ◽  
Vol 88 (3) ◽  
pp. 673-682 ◽  
Author(s):  
K. HINDS ◽  
A.C. LEGON ◽  
J.H. HOLLOWAY
Keyword(s):  
Hydrogen Cyanide ◽  
Rotational Spectrum
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