scholarly journals Effects of molecular confinement and crowding on horseradish peroxidase kinetics using a nanofluidic gradient mixer

Lab on a Chip ◽  
2016 ◽  
Vol 16 (5) ◽  
pp. 877-883 ◽  
Author(s):  
William R. A. Wichert ◽  
Donghoon Han ◽  
Paul W. Bohn

The effects of molecular confinement and crowding on enzyme kinetics were studied at length scales and under conditions similar to those found in biological cells.




The Analyst ◽  
2019 ◽  
Vol 144 (4) ◽  
pp. 1442-1447 ◽  
Author(s):  
Yizhe Yu ◽  
Yinling Wang ◽  
Maoguo Li

A new electrochemical method was proposed to detect the specific activity and study the enzyme kinetics of horseradish peroxidase.



Author(s):  
John L. Beggs ◽  
John D. Waggener ◽  
Wanda Miller

Microtubules (MT) are versatile organelles participating in a wide variety of biological activity. MT involvement in the movement and transport of cytoplasmic components has been well documented. In the course of our study on trauma-induced vasogenic edema in the spinal cord we have concluded that endothelial vesicles contribute to the edema process. Using horseradish peroxidase as a vascular tracer, labeled endothelial vesicles were present in all situations expected if a vesicular transport mechanism was in operation. Frequently,labeled vesicles coalesced to form channels that appeared to traverse the endothelium. The presence of MT in close proximity to labeled vesicles sugg ested that MT may play a role in vesicular activity.



Author(s):  
D. R. Abrahamson ◽  
P. L. St.John ◽  
E. W. Perry

Antibodies coupled to tracers for electron microscopy have been instrumental in the ultrastructural localization of antigens within cells and tissues. Among the most popular tracers are horseradish peroxidase (HRP), an enzyme that yields an osmiophilic reaction product, and colloidal gold, an electron dense suspension of particles. Some advantages of IgG-HRP conjugates are that they are readily synthesized, relatively small, and the immunolabeling obtained in a given experiment can be evaluated in the light microscope. In contrast, colloidal gold conjugates are available in different size ranges and multiple labeling as well as quantitative studies can therefore be undertaken through particle counting. On the other hand, gold conjugates are generally larger than those of HRP but usually can not be visualized with light microscopy. Concern has been raised, however, that HRP reaction product, which is exquisitely sensitive when generated properly, may in some cases distribute to sites distant from the original binding of the conjugate and therefore result in spurious antigen localization.



Author(s):  
Wm. J. Arnold ◽  
J. Russo ◽  
H. D. Soule ◽  
M. A. Rich

Our studies of mammary tumor virus have included the application of the unlabeled antibody enzyme method of Sternberger to mammary tumor derived mouse cells in culture and observation with an electron microscope. The method avoids the extravagance of covalent binding of indicator molecules (horseradish peroxidase) with precious antibody locator molecules by relying instead upon specific antibody-antigen linkages. Our reagents included: Primary Antibody, rabbit anti-murine mammary tumor virus (MuMTV) which was antiserum 113 AV-2; Secondary Antibody, goat anti-rabbit IgG gamma chain (Cappel Laboratories); andthe Indicator, rabbit anti-horseradish peroxidase - horseradish peroxidase complex (PAP) (Cappel Labs.). Dilutions and washes were made in 0.05 M Tris 0.15 M saline buffered to pH 7.4. Cell monolayers, after light fixation in glutaraldehyde, were incubated in place by a protocol adapted from Sternberger and Graham and Karnovsky, then embedded by our usual method for monolayers. Reagents were confined to specific areas by neoprene 0-rings (Parker Seal Co.) reducing the amount of reagent needed to 50 microliters, 1/6th of that required to wet a 35 mm petri dish.



1968 ◽  
Vol 19 (03/04) ◽  
pp. 364-367 ◽  
Author(s):  
H. C Hemker ◽  
P. W Hemker

SummaryThe enzyme kinetics of competitive inhibition under conditions prevailing in clotting tests are developed and a method is given to measure relative amounts of a competitive inhibitor by means of the t — D plot.



1965 ◽  
Vol 13 (01) ◽  
pp. 155-175 ◽  
Author(s):  
H. C Hemker ◽  
P.W Hemker ◽  
E. A Loeliger

SummaryApplication of the methods of enzyme-kinetic analysis to the results of clotting tests is feasible and can yield useful results. However, the standard methods of enzyme kinetics are not applicable without modifications imposed by the peculiarities of the blood-clotting enzyme system. The influence of the following complicating circumstances is calculated :1. Substrate is not present in excess.2. Only relative measures exist for concentrations of substrate or enzymes.3. Enzymes and substrates are often added together.4. Reagents are not pure.5. Clotting-time is our only measure for clotting-velocity.Formulas are deduced, which makes it possible to recognize the effect of these complications.



2020 ◽  
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1990 ◽  
Vol 160 (7) ◽  
pp. 83-104 ◽  
Author(s):  
A.N. Shalygin ◽  
K.A. Krotov


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