scholarly journals An Isotope Effect in a Simple Chemical Reaction

1948 ◽  
Author(s):  
Peter E. Yankwich ◽  
Melvin Calvin
Keyword(s):  
Isotope Effect ◽  
Chemical Reaction ◽  
Simple Chemical

scholarly journals THE RELATIONSHIP BETWEEN SPREADING FACTOR AND HYALURONIDASE

1941 ◽  
Vol 73 (1) ◽  
pp. 109-123 ◽  
Author(s):  
Gladys L. Hobby ◽  
Martin H. Dawson ◽  
Karl Meyer ◽  
Eleanor Chaffee
Keyword(s):  
Hyaluronic Acid ◽  
Comparative Study ◽  
Chemical Reaction ◽  
Spreading Factor ◽  
Hyaluronidase Activity ◽  
Comparable Effect ◽  
Simple Chemical ◽  
The Relationship ◽  
Homologous Enzyme

A comparative study of spreading factor and hyaluronidase in preparations from various sources revealed the following points of similarity and dissimilarity in the two reactions. 1. Similarities: (a) All preparations containing hyaluronidase also produced spreading. (b) Heating at 65° and 100°C. for 30 minutes produced a comparable effect on both reactions. (c) The demonstration of the presence of hyaluronic acid in skin offers a plausible explanation for the mechanism of spreading on the basis of hyaluronidase activity. 2. Dissimilarities: (a) No parallelism was observed in the degree of activity of spreading factor and hyaluronidase in the same preparations. (b) All preparations which produced spreading did not contain hyaluronidase. (c) Antisera to hyaluronidase preparations specifically and completely inhibited the activity of the homologous enzyme but did not inhibit the spreading factor in the same preparations. The significance of the similarities and dissimilarities between the two reactions is discussed. It is concluded that while hyaluronidase may play a rôle in the spreading reaction the phenomenon is a complex one and cannot be explained on the basis of a simple chemical reaction.

The Acetic Anhydride-Sulphuric Reaction for General Paresis

1927 ◽  
Vol 73 (302) ◽  
pp. 419-421 ◽  
Author(s):  
A. G. Duncan
Keyword(s):  
Acetic Anhydride ◽  
Mental Disorder ◽  
Sulphuric Acid ◽  
Positive Reaction ◽  
Chemical Reaction ◽  
Spinal Fluid ◽  
General Paresis ◽  
Simple Chemical

While elaborating a test for cholesterol in the cerebro-spinal fluid, 0. H. Boltz (I) observed and investigated a reaction which occurred predominantly in cases of neuro-syphilis, and which he named the acetic anhydride-sulphuric test. To I c.c. of spinal fluid was added 03 c.c. of acetic anhydride, drop by drop, and after mixing the fluids by shaking, [email protected]. of concentrated sulphuric acid was added in drops, and the mixture shaken again. The development of a blue pink or lilac colour characterized a positive reaction. The test has been studied in this country, and it has been claimed that the reaction is positive in almost every case of general paresis, and negative in almost every other type of mental disorder, except certain cases of non-paretic neuro-syphilis. As this constitutes a surprising degree of specificity of an apparently simple chemical reaction for a single disease, I have carried out the reaction in association with the routine tests in a series of cerebro-spinal fluids with a view to ascertaining its value. One hundred and sixty fluids were examined—a comparatively small number on which to base conclusions, but the results will show that the claims previously advanced for the value of the test require considerable modification.

scholarly journals Use of an asparaginyl endopeptidase for chemo-enzymatic peptide and protein labeling

2020 ◽  
Vol 11 (23) ◽  
pp. 5881-5888 ◽  
Author(s):  
T. M. Simon Tang ◽  
Davide Cardella ◽  
Alexander J. Lander ◽  
Xuefei Li ◽  
Jorge S. Escudero ◽  
...  
Keyword(s):  
Chemical Reaction ◽  
Protein Labeling ◽  
Asparaginyl Endopeptidase ◽  
Simple Chemical

Asparaginyl endopeptidases (AEP) are ideal for peptide and protein labeling. Its pairing with a simple chemical reaction significantly lowers the amount of label needed for effective bioconjugation.

scholarly journals A numerical study on reaction-induced radial fingering instability

2019 ◽  
Vol 862 ◽  
pp. 624-638 ◽  
Author(s):  
Vandita Sharma ◽  
Satyajit Pramanik ◽  
Ching-Yao Chen ◽  
Manoranjan Mishra
Keyword(s):  
Chemical Reaction ◽  
Reaction Rate ◽  
Numerical Study ◽  
Stable Region ◽  
Global Maximum ◽  
Good Qualitative Agreement ◽  
Viscosity Profile ◽  
Fingering Instability ◽  
Simple Chemical ◽  
Chemical Reaction Rate

The dynamics of $A+B\rightarrow C$ fronts is analysed numerically in a radial geometry. We are interested to understand miscible fingering instabilities when the simple chemical reaction changes the viscosity of the fluid locally and a non-monotonic viscosity profile with a global maximum or minimum is formed. We consider viscosity-matched reactants $A$ and $B$ generating a product $C$ having different viscosity than the reactants. Depending on the effect of $C$ on the viscosity relative to the reactants, different viscous fingering (VF) patterns are captured which are in good qualitative agreement with the existing radial experiments. We have found that, for a given chemical reaction rate, an unfavourable viscosity contrast is not always sufficient to trigger the instability. For every fixed Péclet number ($Pe$), these effects of chemical reaction on VF are summarized in the Damköhler number ($Da$) $-$ the log-mobility ratio ($R_{c}$) parameter space that exhibits a stable region separating two unstable regions corresponding to the cases of more and less viscous product. Fixing $Pe$, we determine $Da$-dependent critical log-mobility ratios $R_{c}^{+}$ and $R_{c}^{-}$ such that no VF is observable whenever $R_{c}^{-}\leqslant R_{c}\leqslant R_{c}^{+}$. The effect of geometry is observable on the onset of instability, where we obtain significant differences from existing results in the rectilinear geometry.

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