Chemical Modification of the Active Center of Nitrogenase

1992 ◽  
pp. 251-264
Author(s):  
X. P. Dai ◽  
J. S. Yang ◽  
C. G. Zhang
Keyword(s):  
Chemical Modification ◽  
Active Center

Kinetic Study of the Effect of Heparin on the Amidase Activity of Trypsin, Plasmin and Urokinase

1983 ◽  
Vol 49 (03) ◽  
pp. 199-203 ◽  
Author(s):  
V M Yomtova ◽  
N A Stambolieva ◽  
B M Blagoev
Keyword(s):  
Kinetic Study ◽  
Active Center ◽  
Simultaneous Presence ◽  
Amidase Activity ◽  
Competitive Inhibitors ◽  
Uncompetitive Inhibitor

SummaryIt was found that the effect of heparin on the amidase activity of urokinase (E C 3.4.21.31), plasmin (E C 3.4.21.7) and trypsin (E C 3.4.21.4) depended on the substrate used. No effect of heparin on the amidase activity of urokinase and trypsin was observed when Pyro Glu-Gly-Arg-p-nitroanilide (S-2444) and α-N-acetyl-L-lysine-p-nitroanilide (ALNA) were used as substrates. Heparin acted as a uncompetitive inhibitor of trypsin (Ki = 1.2×10-6 M), plasmin (Ki = 4.9×10-6 M) and urokinase (Ki = l.0×10-7 M) when Bz-Phe-Val-Arg-p-nitroanilide (S-2160), H-D-Val-Leu-Lys-p-nitroanilide (S-2251) and plasminogen, respectively, were used as substrates. These results, as well as the data obtained by studying the effect of the simultaneous presence of heparin and competitive inhibitors suggest that although heparin is not bound at the active center of these enzymes, it may influence the effectivity of catalysis.

Photoconductivity in Vacuum Deposited Films of Silicon-Based Polymers

1996 ◽  
Vol 444 ◽  
Author(s):  
H. Okumoto ◽  
M. Shimomura ◽  
N. Minami ◽  
Y. Tanabe
Keyword(s):  
Charge Transfer ◽  
Chemical Modification ◽  
Electronic Transport ◽  
Hole Transport ◽  
Electron Acceptors ◽  
Oxygen Atmosphere ◽  
Dangling Bonds ◽  
Silicon Based ◽  
Deposited Films

AbstractSilicon-based polymers with σconjugated electrons have specific properties; photoreactivity for microlithography and photoconductivity for hole transport materials. To explore the possibility of combining these two properties to develop photoresists with electronic transport capability, photoconductivity of polysilanes is investigated in connection with their photoinduced chemical modification. Increase in photocurrent is observed accompanying photoreaction of poly(dimethylsilane) vacuum deposited films. This increase is found to be greatly enhanced in oxygen atmosphere. Such changes of photocurrent can be explained by charge transfer to electron acceptors from Si dangling bonds postulated to be formed during photoreaction.

Matrix metalloproteinases: structure, functions and genetic polymorphism

2017 ◽  
pp. 14-23
Author(s):  
А.С. Шадрина ◽  
И.В. Терешкина ◽  
Я.З. Плиева ◽  
Д.Н. Кушлинский ◽  
Д.О. Уткин ◽  
...  
Keyword(s):  
Genetic Polymorphism ◽  
Matrix Metalloproteinases ◽  
Active Center ◽  
Human Body ◽  
Enzymatic Catalysis ◽  
Structure Functions ◽  
Zinc Ion ◽  
Etiological Factors ◽  
Mmp Genes

Матриксные металлопротеиназы (ММП) - ферменты класса гидролаз, осуществляющие ферментативный катализ с помощью связанного в активном центре иона цинка. Функции ММП разнообразны, и нарушение баланса их активности может быть одним из этиологических факторов различных заболеваний. В данном обзоре рассмотрена классификация ММП человека, особенности их структуры и регуляции, а также роль в физиологических и патологических процессах в организме человека. Приведен перечень наиболее изученных на настоящий момент полиморфных вариантов генов MMП, описаны их функциональные эффекты и представлены результаты ассоциативных исследований. Matrix metalloproteinases (MMPs) are enzymes of the hydrolase class that carry out enzymatic catalysis with the help of a zinc ion bound in the active center. MMP functions are diverse, and a disturbance in the balance of their activity may be one of the etiological factors of various diseases. In this review, the classification of human MMP, the features of their structure and regulation, as well as the role in physiological and pathological processes in the human body are considered. A list of the most studied polymorphic versions of MMP genes has been given, their functional effects have been described, and the results of associative studies have been presented.

Chemical modification of lignin-rich paper

1998 ◽  
Vol 13 (2) ◽  
pp. 124-131 ◽  
Author(s):  
Magnus Paulsson ◽  
Arthur J. Ragauskas
Keyword(s):  
Chemical Modification
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