scholarly journals Comparative studies of the specificities of α-chymotrypsin and subtilisin BPN′. Studies with flexible and ‘locked’ substrates

1972 ◽  
Vol 126 (3) ◽  
pp. 659-665 ◽  
Author(s):  
T. N. Pattabiraman ◽  
W. B. Lawson
Keyword(s):  
Methyl Ester ◽  
Carbon Atom ◽  
Binding Site ◽  
Comparative Studies ◽  
Detrimental Effect ◽  
Optically Active ◽  
The Other ◽  
Optical Isomers ◽  
Polar Groups ◽  
Hydrolysis Of

Subtilisin BPN′ hydrolysed N-acetyl-l-3-(2-naphthyl)-alanine methyl ester, N-acetyl-l-leucine methyl ester and N-acetyl-l-valine methyl ester, faster than α-chymotrypsin. Of eight ‘locked’ substrates tested, only methyl 5,6-benzindan-2-carboxylate was hydrolysed faster by subtilisin, whereas the other esters were better substrates for chymotrypsin. Compared with the values for chymotrypsin, the stereospecific ratios during the hydrolysis of the optically active locked substrates by subtilisin were decreased by one and two orders of magnitude for bi- and tri-cyclic substrates respectively. The polar groups adjacent to the α-carbon atom of locked substrates did not contribute significantly to the reactivity of the more active optical isomers, but had a detrimental effect on the less active antipodes during hydrolysis by both the enzymes. These studies show that the binding site of subtilisin BPN′ is longer and broader than that of α-chymotrypsin.

scholarly journals Comparative studies of the specificities of α-chymotrypsin and subtilisin BPN′. Studies with flexible substrates

1972 ◽  
Vol 126 (3) ◽  
pp. 645-657 ◽  
Author(s):  
T. N. Pattabiraman ◽  
W. B. Lawson
Keyword(s):  
Methyl Ester ◽  
Binding Site ◽  
Comparative Studies ◽  
Detrimental Effect ◽  
Flexible Substrates ◽  
Enhancing Effect ◽  
Wide Range ◽  
Phenylalanine Methyl Ester ◽  
Hydrolysis Of ◽  
Tryptophan Methyl Ester

A series of arylalkanoate esters and α-acetamidoarylalkanoate esters were tested as substrates for α-chymotrypsin and subtilisin BPN′. Chymotrypsin hydrolysed N-acetyl-l-phenylalanine methyl ester and methyl 4-phenylbutyrate faster than their respective higher and lower homologues, whereas methyl 2-acetamido-6-phenylhexanoate and methyl 6-phenylhexanoate were better substrates for subtilisin than their lower homologues. N-Acetyl-l-tryptophan methyl ester and its analogue, N-acetyl-3-(1-naphthyl)-alanine methyl ester, were hydrolysed 23 times faster by chymotrypsin than by subtilisin. These results indicate that the binding site of α-chymotrypsin is roughly 1.1nm (11Å) long and curved, whereas that of subtilisin is a longer system and less curved. The stereo-specificity during the hydrolysis of typical substrates by both enzymes was found to vary over a wide range. The enhancing effect of the α-acetamido group in the l-series of substrates and the detrimental effect in the d-series of substrates also varies considerably.

Activity of Plasmin and Streptokinase-Activator on Substituted Arginine and Lysine Esters

1966 ◽  
Vol 16 (01/02) ◽  
pp. 018-031 ◽  
Author(s):  
S Sherry ◽  
Norma Alkjaersig ◽  
A. P Fletcher
Keyword(s):  
Molecular Structure ◽  
Methyl Ester ◽  
Comparative Studies ◽  
Esterase Activity ◽  
Methyl Esters ◽  
Hydrolytic Activity ◽  
The Other ◽  
Other Hand

SummaryComparative studies have been made of the esterase activity of plasmin and the streptokinase-activator of plasminogen on a variety of substituted arginine and lysine esters. Human plasmin preparations derived by different methods of activation (spontaneous in glycerol, trypsin, streptokinase (SK) and urokinase) are similar in their esterase activity; this suggests that the molecular structure required for such esterase activity is similar for all of these human plasmins. Bovine plasmin, on the other hand, differs from human plasmin in its activity on several of the substrates studied (e.g., the methyl esters of benzoyl arginine and tosyl, acetyl and carbobenzoxy lysine), a finding which supports the view that molecular differences exist between the two animal plasmins. The streptokinase-activator hydrolyzes both arginine and lysine esters but the ratios of hydrolytic activity are distinct from those of plasmin and of other activators of plasminogen. The use of benzoyl arginine methyl ester as a substrate for the measurement of the esterase activity of the streptokinase-activator is described.

scholarly journals Change in Substrate Preference of Streptomyces Aminopeptidase through Modification of the Environment around the Substrate Binding Site

2006 ◽  
Vol 72 (12) ◽  
pp. 7962-7967 ◽  
Author(s):  
Jiro Arima ◽  
Yoshiko Uesugi ◽  
Masaki Iwabuchi ◽  
Tadashi Hatanaka
Keyword(s):  
Binding Site ◽  
Substrate Binding ◽  
The Other ◽  
Substrate Preference ◽  
Wild Type ◽  
Substrate Binding Site ◽  
Hydrolysis Of

ABSTRACT We attempted to alter the substrate preference of aminopeptidase from Streptomyces septatus TH-2 (SSAP). Because Asp198 and Phe221 of SSAP are located in the substrate binding site, we screened 2,000 mutant enzymes with D198X/F221X mutations. By carrying out this examination, we obtained two enzymes; one specifically hydrolyzed an arginyl derivative, and the other specifically hydrolyzed a cystinyl derivative (65- and 12.5-fold higher k cat values for hydrolysis of p-nitroanilide derivatives than those of the wild type, respectively).

Some Observations on the Hydrolysis of the Amides of Primary α-Acetylenic Amines

1973 ◽  
Vol 51 (9) ◽  
pp. 1416-1418 ◽  
Author(s):  
John Nicholson Gardner
Keyword(s):  
Carbon Atom ◽  
Triple Bond ◽  
The Other ◽  
Ritter Reaction ◽  
Ethynyl Group ◽  
Acetylenic Amine ◽  
The Ritter Reaction ◽  
Hydrolysis Of

Some amides of primary α-acetylenic amines were made from the corresponding α-acetylenic alcohols by the Ritter reaction. Depending upon the other substituents on the carbon atom bearing nitrogen and the ethynyl group, hydrolysis resulted in formation of the α-acetylenic amine or in hydration of the triple bond to yield a ketone.

LYTIC ENZYMES OF SORANGIUM SP.: A COMPARISON OF THE PROTEOLYTIC PROPERTIES OF THE α- AND β-LYTIC PROTEASES

1965 ◽  
Vol 43 (12) ◽  
pp. 1961-1970 ◽  
Author(s):  
D. R. Whitaker ◽  
C. Roy ◽  
C. S. Tsai ◽  
L. Jurášek
Keyword(s):  
Amino Acids ◽  
Amino Acid ◽  
Methyl Ester ◽  
Esterase Activity ◽  
The Other ◽  
Carboxyl Group ◽  
Lytic Enzymes ◽  
Amidase Activity ◽  
A Chain ◽  
Hydrolysis Of

The proteolytic properties of the α- and β-lytic proteases of a species of Sorangium were compared. Neither enzyme showed evidence of aminopeptidase, carboxypeptidase, or amidase activity in tests with a series of peptides and substituted amino acids at pH 5.2, 7.2, and 9.0. Neither enzyme showed evidence of esterase activity towards N-benzoyl-L-arginine methyl ester at pH 6.8. Hydrolysis of the A chain of oxidized insulin at pH 9 slows down markedly when the α-enzyme has cleaved the chain once; the initial fast cleavage can take place at linkages between residues 9 and 10, 10 and 11, and 12 and 13; more slowly cleaved linkages are between residues 3 and 4, and 8 and 9. Hydrolysis of the B chain by the α-enzyme at pH 9 is still faster and slows down when the chain has been cleaved twice. One fast cleavage is at the linkage between residues 18 and 19; the other can take place at the linkages between residues 12 and 13, and 14 and 15; more slowly cleaved linkages are between residues 8 and 9, 9 and 10, and 15 and 16. Under the conditions tested, the β-enzyme does not hydrolyze the A chain appreciably at pH 9. It cleaves the B chain rapidly at the linkage between residues 23 and 24 and more slowly at linkages between residues 18 and 19. The linkages split by both enzymes are those which involve the carboxyl group of a neutral amino acid.

A FACILE SYNTHESIS AND REACTIONS OF AMINO SELENOLO[2,3-b]PYRIDINE CARBOXYLATE

2015 ◽  
Vol 12 (1) ◽  
pp. 3910-3918 ◽  
Author(s):  
Dr Remon M Zaki ◽  
Prof Adel M. Kamal El-Dean ◽  
Dr Nermin A Marzouk ◽  
Prof Jehan A Micky ◽  
Mrs Rasha H Ahmed
Keyword(s):  
Biological Activity ◽  
Carbonyl Compounds ◽  
Mass Spectra ◽  
The Other ◽  
Pyridine Derivatives ◽  
Facile Synthesis ◽  
High Biological Activity ◽  
Basic Hydrolysis ◽  
Pyridine Carboxylate ◽  
Hydrolysis Of

 Incorporating selenium metal bonded to the pyridine nucleus was achieved by the reaction of selenium metal with 2-chloropyridine carbonitrile 1 in the presence of sodium borohydride as reducing agent. The resulting non isolated selanyl sodium salt was subjected to react with various α-halogenated carbonyl compounds to afford the selenyl pyridine derivatives 3a-f  which compounds 3a-d underwent Thorpe-Ziegler cyclization to give 1-amino-2-substitutedselenolo[2,3-b]pyridine compounds 4a-d, while the other compounds 3e,f failed to be cyclized. Basic hydrolysis of amino selenolo[2,3-b]pyridine carboxylate 4a followed by decarboxylation furnished the corresponding amino selenolopyridine compound 6 which was used as a versatile precursor for synthesis of other heterocyclic compound 7-16. All the newly synthesized compounds were established by elemental and spectral analysis (IR, 1H NMR) in addition to mass spectra for some of them hoping these compounds afforded high biological activity.

PERBANDINGAN METODE MD4 DAN SHA 384 UNTUK MENDETEKSI ORISINALITAS CITRA DIGITAL

2019 ◽  
Vol 3 (1) ◽  
Author(s):  
Lemcia Hutajulu ◽  
Hery Sunandar ◽  
Imam Saputra
Keyword(s):  
Digital Image ◽  
Detrimental Effect ◽  
Digital Images ◽  
Computer Crime ◽  
The Other ◽  
Image Manipulation ◽  
The Internet ◽  
Secret Key

Cryptography is used to protect the contents of information from anyone except those who have the authority or secret key to open information that has been encoded. Along with the development of technology and computers, the increase in computer crime has also increased, especially in image manipulation. There are many ways that people use to manipulate images that have a detrimental effect on others. The originality of a digital image is the authenticity of the image in terms of colors, shapes, objects and information without the slightest change from the other party. Nowadays many digital images circulating on the internet have been manipulated and even images have been used for material fraud in the competition, so we need a method that can detect the image is genuine or fake. In this study, the authors used the MD4 and SHA-384 methods to detect the originality of digital images, by using this method an image of doubtful authenticity can be found out that the image is authentic or fake.Keywords: Originality, Image, MD4 and SHA-384

Constructing Prophetic Divination

2017 ◽  
Author(s):  
Martti Nissinen
Keyword(s):  
Comparative Studies ◽  
Theoretical Foundation ◽  
Eastern Mediterranean ◽  
Source Material ◽  
The Other ◽  
Near Eastern ◽  
Common Category ◽  
Divine Knowledge ◽  
Historical Phenomenon

This chapter lays the theoretical foundation of the book, defining prophecy as a non-technical, or inspired, form of divination, in which the prophet acts as an intermediary of divine knowledge. It is argued that prophecy is as much a scholarly construct as a historical phenomenon documented in Near Eastern, biblical, as well as Greek textual sources. The knowledge of the historical phenomenon depends essentially on the genre and purpose of the source material which, however, is very fragmentary and, due to its secondary nature, does not yield a full and balanced picture of ancient prophecy. The chapter also discusses the purpose of comparative studies, arguing that they are necessary, not primarily to reveal the influence of one source on the other, but to identify a common category of ancient Eastern Mediterranean prophecy.

scholarly journals Adjustment of Hydrophobic Properties of Cellulose Materials

Polymers ◽  
2021 ◽  
Vol 13 (8) ◽  
pp. 1241
Author(s):  
Michael Ioelovich
Keyword(s):  
Ester Group ◽  
Hydroxyl Groups ◽  
Chemical Methods ◽  
Hydrophobic Properties ◽  
Cellulose Esters ◽  
Cellulose Modification ◽  
Polar Groups ◽  
Polar Substituents ◽  
Hydrolysis Of ◽  
Cellulose Materials

In this study, physicochemical and chemical methods of cellulose modification were used to increase the hydrophobicity of this natural semicrystalline biopolymer. It has been shown that acid hydrolysis of the initial cellulose increases its crystallinity, which improves hydrophobicity, but only to a small extent. A more significant hydrophobization effect was observed after chemical modification by esterification, when polar hydroxyl groups of cellulose were replaced by non-polar substituents. The esterification process was accompanied by the disruption of the crystalline structure of cellulose and its transformation into the mesomorphous structure of cellulose esters. It was found that the replacement of cellulose hydroxyls with ester groups leads to a significant increase in the hydrophobicity of the resulting polymer. Moreover, the increase of the number of non-polar groups in the ester substituent contributes to rise in hydrophobicity of cellulose derivative. Depending on the type of ester group, the hydrophobicity increased in the following order: acetate < propionate < butyrate. Therefore, tributyrate cellulose (TBC) demonstrated the most hydrophobicity among all studied samples. In addition, the mixed ester, triacetobutyrate cellulose (TAB), also showed a sufficiently high hydrophobicity. The promising performance properties of hydrophobic cellulose esters, TBC and TAB, were also demonstrated.

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