scholarly journals NADPH binding and control of catalase compound II formation: comparison of bovine, yeast, and Escherichia coli enzymes

1994 ◽  
Vol 300 (2) ◽  
pp. 531-539 ◽  
Author(s):  
A Hillar ◽  
P Nicholls ◽  
J Switala ◽  
P C Loewen
Keyword(s):  
Escherichia Coli ◽  
Catalytic Activity ◽  
Free Radical ◽  
Compound I ◽  
Radical Species ◽  
New Type ◽  
Compound Ii ◽  
And Control ◽  
Original Classification

1. NADPH binds to bovine catalase and to yeast catalases A and T, but not to Escherichia coli catalase HPII. The association was demonstrated using chromatography and fluorimetry. Bound NADPH fluoresces in a similar way to NADPH in solution. 2. Bound NADPH protects bovine and yeast catalases against forming inactive peroxide compound II either via endogenous reductant action or by ferrocyanide reduction during catalytic activity in the presence of slowly generated peroxide. 3. Bound NADPH reduces neither compound I nor compound II of catalase. It apparently reacts with an intermediate formed during the decay of compound I to compound II; this postulated intermediate is an immediate precursor of stable compound II either when the latter is formed by endogenous reductants or when ferrocyanide is used. It represents therefore a new type of hydrogen donor that is not included in the original classification of Keilin and Nicholls [Keilin, D. and Nicholls, P. (1958) Biochim. Biophys. Acta 29, 302-307] 4. A model for NADPH action is presented in which concerted reduction of the ferryl iron and of a neighbouring protein free radical is responsible for the observed NADPH effects. The roles of migrant radical species in mammalian and yeast catalases are compared with similar events in metmyoglobin and cytochrome c peroxidase reactions with peroxides.

Reaction of ferric Caldariomyces fumago chloroperoxidase with meta-chloroperoxybenzoic acid: sequential formation of compound I, compound II and regeneration of the ferric state using one reactant

2013 ◽  
Vol 17 (01n02) ◽  
pp. 63-72 ◽  
Author(s):  
Daniel P. Collins ◽  
Issa S. Isaac ◽  
Eric D. Coulter ◽  
Paul W. Hager ◽  
David P. Ballou ◽  
...  
Keyword(s):  
Organic Substrate ◽  
Compound I ◽  
Radical Species ◽  
Caldariomyces Fumago ◽  
Saturation Kinetics ◽  
Oxygen Insertion ◽  
Compound Ii ◽  
Sequential Formation ◽  
Mechanism Of The Reaction

The mechanism of the reaction between ferric Caldariomyces fumago chloroperoxidase (CCPO) and meta-chloroperoxybenzoic acid (mCPBA) has been examined. It has previously been established that an Fe(IV) -oxo porphyrin radical species known as Compound I (Cpd I) is formed by two-electron oxidation of the native ferric enzyme by a variety of oxidants including organic peracids and hydroperoxides. Cpd I can return to the ferric state either by direct oxygen insertion into an organic substrate (e.g. a P450 oxygenase-like reaction), or by two consecutive one-electron additions, the first resulting in an intermediate Fe(IV) -oxo species known as Compound II (Cpd II). There has been much debate over the role of Cpd II and the details of its structure. In the present study, both CCPO Fe(IV) -oxo intermediates are formed, but unlike most CCPO reactions, Cpd I and Cpd II are formed using the same reactant, mCPBA. Thus, the peracid is used as an oxo donor to produce Cpd I and then as a reductant to reduce Cpd I to Cpd II, and finally, Cpd II to the ferric state. The observation of saturation kinetics with respect to mCPBA concentration for each step is consistent with the formation of CCPO-mCPBA complexes in each phase of the reaction. The original reaction mechanism for ferric CCPO with mCPBA was hypothesized to involve a scrambling mechanism with a unique Fe -OOO-C(O)R intermediate formed with no observed Cpd II intermediate. The data reported herein clearly demonstrate the formation of Cpd II in returning the oxidized enzyme back to its native ferric state.

scholarly journals The formation of ferric haem during low-temperature photolysis of horseradish peroxidase Compound I

1987 ◽  
Vol 246 (3) ◽  
pp. 659-668 ◽  
Author(s):  
N Foote ◽  
P M A Gadsby ◽  
M J Berry ◽  
C Greenwood ◽  
A J Thomson
Keyword(s):  
Electronic Structure ◽  
Free Radical ◽  
Low Temperature ◽  
Horseradish Peroxidase ◽  
Spectral Features ◽  
Photolysis Product ◽  
Compound I ◽  
Radical Species ◽  
Step Process ◽  
Peroxide Compound

Illumination at low temperature of the peroxide compound of horseradish peroxidase (HRP-I) causes partial conversion of the haem electronic structure from a ferryl-porphyrin radical species into a low-spin ferric state. Magnetic-c.d. (m.c.d.) and e.p.r. spectral features of the photolysis product are almost identical with those of the alkaline form of ferric HRP, proposed on the basis of its near-i.r. m.c.d. spectrum to be a Fe(III)-OH species. The ferric product of HRP-I photolysis also contains free-radical e.p.r. signals. Conversion of HRP-I into the Fe(III)-OH species, which requires transfer of a proton and two electrons from the protein, is shown to be a two-step process.

To Understand the Informal (on the Book BY V. L. Tambovtsev “Economics of Informal Institutions”)

2015 ◽  
pp. 151-158
Author(s):  
A. Zaostrovtsev
Keyword(s):  
Social Psychology ◽  
Detailed Analysis ◽  
Human Behavior ◽  
Interdisciplinary Approach ◽  
Informal Institutions ◽  
Economic Thought ◽  
History Of ◽  
Original Classification

The review considers the first attempt in the history of Russian economic thought to give a detailed analysis of informal institutions (IF). It recognizes that in general it was successful: the reader gets acquainted with the original classification of institutions (including informal ones) and their genesis. According to the reviewer the best achievement of the author is his interdisciplinary approach to the study of problems and, moreover, his bias on the achievements of social psychology because the model of human behavior in the economic mainstream is rather primitive. The book makes evident that namely this model limits the ability of economists to analyze IF. The reviewer also shares the author’s position that in the analysis of the IF genesis the economists should highlight the uncertainty and reject economic determinism. Further discussion of IF is hardly possible without referring to this book.

Study effect of crude extracts of Hibiscus sabdarifa L. on some Enterobacteriaceae

2018 ◽  
Vol 9 (SPL1) ◽  
Author(s):  
Sabreen A Kamal ◽  
Ishraq A Salih ◽  
Hawraa Jawad Kadhim ◽  
Zainab A Tolaifeh
Keyword(s):  
Escherichia Coli ◽  
Ethyl Acetate ◽  
Bacterial Growth ◽  
Chemical Compounds ◽  
Inhibition Zone ◽  
Crude Extracts ◽  
And Control

Red rose or roselle (beauty rose ) is natively known as red tea belong to Malvaceae, it is flowers use traditionally for antihypertensive hepato protective, anticancer,antidiabetic,antibacterial, cytotoxicity and antidiarreal, By preparing red tea from it's flower. In this study, we extract chemical compounds by using two solvent which are Ethanol, Ethyl acetate. so we can extract Anthocyanin which is responsible for red colour of flower with many chemical compounds. then study the effect of these extracts on 5 genera from Enterobacteriacaea which can cause diarrheae (Shigella, Salmonella, Escherichia coli, Proteus and Klebsiella ) by preparing 3 concentrations for each solvent (250, 500, 750 ) mg/ml, and control then compare with two antibiotic (Azereonam 30 mg/ml and Bacitracin 10 mg/ml ) these extracts revealed obvious inhibition zone in bacterial growth.

Performance of 4G-LTE Communication and Navigation System in Blended Wing-Body UAS

2019 ◽  
Vol 8 (4) ◽  
pp. 9538-9542
Keyword(s):  
Satellite Communication ◽  
Line Of Sight ◽  
Multiple Factors ◽  
The World ◽  
New Type ◽  
Blended Wing Body ◽  
4G Lte ◽  
The Right ◽  
And Control ◽  
Technology Demonstrator

In vision of searching for the right Unmanned Aerial System (UAS) for a specific mission, there are multiple factors to be considered by the operator such as mission, endurance, type of payload and range of the telemetry and control. This research is focusing on extending control range of the UAS by using 4G-LTE network to enable beyond-line-of-sight flying for the commercial UAS. Major UAS such Global Hawk, Predator MQ-1 are able to fly thousands of kilometers by the use of satellite communication. However, the satellite communication annual license subscription can be very expensive. With this situation in mind, a new type of flight controller with 4G-LTE communication has been developed and tested. Throughout the research, blended-wing-body (BWB) Baseline B2S is used as the platform for technology demonstrator. Result from this analysis has proven that the proposed system is capable to control a UAS from as far as United Kingdom, with a latency less than 881 ms in average. The new added capability can potentially give the commercial UAS community a new horizon to be able to control their UAS from anywhere around the world with the availability of 4G-LTE connection

Learning and control

2018 ◽  
Author(s):  
Ivan Herreros
Keyword(s):  
Machine Learning ◽  
Reinforcement Learning ◽  
Brain Function ◽  
Control Strategies ◽  
Learning Problems ◽  
Animal Learning ◽  
Feed Forward Control ◽  
Machine Learning Applications ◽  
And Control

This chapter discusses basic concepts from control theory and machine learning to facilitate a formal understanding of animal learning and motor control. It first distinguishes between feedback and feed-forward control strategies, and later introduces the classification of machine learning applications into supervised, unsupervised, and reinforcement learning problems. Next, it links these concepts with their counterparts in the domain of the psychology of animal learning, highlighting the analogies between supervised learning and classical conditioning, reinforcement learning and operant conditioning, and between unsupervised and perceptual learning. Additionally, it interprets innate and acquired actions from the standpoint of feedback vs anticipatory and adaptive control. Finally, it argues how this framework of translating knowledge between formal and biological disciplines can serve us to not only structure and advance our understanding of brain function but also enrich engineering solutions at the level of robot learning and control with insights coming from biology.

3-D structure of the D153G mutant of Escherichia coli alkaline phosphatase: an enzyme with weaker magnesium binding and increased catalytic activity

1995 ◽  
Vol 8 (9) ◽  
pp. 865-871 ◽  
Author(s):  
Chris G. Dealwis ◽  
Liqing Chen ◽  
Catherine Brennan ◽  
Wlodek Mandecki ◽  
Cele Abad-Zapatero
Keyword(s):  
Escherichia Coli ◽  
Alkaline Phosphatase ◽  
Catalytic Activity ◽  
Magnesium Binding
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