Inactivation of enzymically modified trypsin inhibitors upon chemical modification of the α-amino group in the reactive site

Biochemistry ◽  
1972 ◽  
Vol 11 (18) ◽  
pp. 3451-3459 ◽  
Author(s):  
David Kowalski ◽  
Michael Laskowski
Keyword(s):  
Chemical Modification ◽  
Trypsin Inhibitors ◽  
Amino Group ◽  
Reactive Site

Chemical modification of crystal-like mesoporous phenylene-silica with amino group

2008 ◽  
pp. 841-843 ◽  
Author(s):  
Masataka Ohashi ◽  
Mahendra P. Kapoor ◽  
Shinji Inagaki
Keyword(s):  
Chemical Modification ◽  
Amino Group

scholarly journals Trypsin inhibitors in turnip (Brassica rapa L.) seeds

2014 ◽  
Vol 58 (4) ◽  
pp. 563-573 ◽  
Author(s):  
Anna Wilimowska-Pelc
Keyword(s):  
Molecular Weight ◽  
Peptide Bond ◽  
Ion Exchange Chromatography ◽  
Trypsin Inhibitors ◽  
Exchange Chromatography ◽  
Trypsin Activity ◽  
Reactive Site ◽  
Salting Out ◽  
Similar Molecular Weight ◽  
Immobilized Trypsin

A method of trypsin inhibitors isolation from turnip seeds is described. Inhibitors were extracted with 0.01 N HCI, concentrated by salting out with ammonium sulfate, and purified using ion-exchange chromatography on Sp-Sephadex C-25, QAE-Sephadex A-25 and affinity chromatography on immobilized trypsin. Among the three isolated inhibitors, ITR I of molecular weight 15.9 kDa, pl. 6,4, inhibited trypsin activity only. Inhibitors ITR II and ITR Ill inhibited also chymotrypsin activity, they had similar molecular weight (about 10 kDa), but their pI is 7.5 and over 10, respectively. Arginine residue occurred in P, position of the reactive site of inhibitors ITR I and ITR III, while in ITR 11 this position was occupied by lysine residue. Electrophoresis on polyacrylamide gel revealed that each inhibitor possessed two protein fractions, probably a virgin and modified form, with the reactive site peptide bond broken by trypsin.

scholarly journals The Reactive Site of Trypsin Inhibitors

1966 ◽  
Vol 241 (17) ◽  
pp. 3955-3961 ◽  
Author(s):  
Kyoichi Ozawa ◽  
Michael Laskowski
Keyword(s):  
Trypsin Inhibitors ◽  
Reactive Site

Study of Ion—Molecule Reactions and Collisionally-Activated Dissociation of Dopamine and Adrenaline by an Ion Trap Mass Spectrometer with An External Ionization Source

2000 ◽  
Vol 6 (1) ◽  
pp. 65-77 ◽  
Author(s):  
Hui-Fen Wu ◽  
Ya-Ping Lin
Keyword(s):  
Mass Spectrometer ◽  
Reaction Mechanisms ◽  
Chemical Ionization ◽  
Ion Trap ◽  
Hydroxyl Group ◽  
Amino Group ◽  
Reactive Site ◽  
Ionization Source ◽  
Ion Trap Mass Spectrometer ◽  
Ion Molecule Reactions

Study of the reaction mechanisms for ion–molecule reactions and for collisionally-activated dissociations (CAD) of dopamine and adrenaline has been performed using an external chemical ionization source quadrupole ion trap mass spectrometer. This work demonstrates the possibility of applying an external source ion trap instrument to perform selective ion–molecule reactions in the gas phase, due to its high sensitivity and low detection limits in mass spectrometry/mass spectrometry (MS/MS) mode. CAD experiments on ions with relative intensity as low as 0–2%, formed as ion–molecule products of dopamine and adrenaline, have been successfully performed. Study of some fragment ions of M+• and [M + H]+, observed in the chemical ionization (CI) spectra, by CAD techniques, permits elucidation of a series of mechanisms for the sequential dissociations of the M+• and [M + H]+ ions. Thus, the structural information obtained from this method is similar to that which would have been obtained if MS n had been performed for M+• and [M + H]+ ions. From the proposed CAD reaction mechanisms and the semi-empirical calculations, the favored reactive sites for formation of the adduct ions could be determined. The reactive site for protonation of dopamine is on the amino group, but for adrenaline, it is on the benzylic hydroxyl group. As to the reactive site for the CH3O=C2H+ ion addition, dopamine is either on the amino group or on the phenyl ring. However, adrenaline is only on the benzylic hydroxyl group. Temperature effects on the formation of the ion–molecule products were also investigated. It was shown that the best source temperature for formation of [M + H]+ and [M + 13]+ ions of dopamine is 200°C. Information about use of dimethyl ether (DME) as the reagent gas in the external chemical ionization of an ion trap mass spectrometer is provided.

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