19F nuclear magnetic resonance studies of the interaction of inhibitors with chymotrypsin. Ring-fluorinated derivatives of N-trifluoroacetylphenylalanine

1978 ◽  
Vol 31 (10) ◽  
pp. 2179 ◽  
Author(s):  
M Tsavalos ◽  
BC Nicholson ◽  
TM Spotswood
Keyword(s):  
Amino Acids ◽  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Chemical Shift ◽  
Active Site ◽  
Enzyme Inhibitor ◽  
Aromatic Amino Acids ◽  
Binding Parameters ◽  
Magnetic Resonance Studies ◽  
Derivatives Of

The complexes formed between chymotrypsin and the doubly fluorine- labelled inhibitors, o-, m- and p-fluoro-N-trifluoroacetyl-D- phenylalanine and 2,4-difluoro-N-trifluoroacetyl-D-phenylalanine, have been characterized by 19F N.M.R. spectroscopy and binding parameters, ΔB and KI, have been derived. The results confirm the importance of the amido binding site in orienting aromatic amino acids at the active site of chymotrypsin. Changes in ΔB, the change in chemical shift of the enzyme-bound inhibitor, are shown to be a very sensitive probe of enzyme-inhibitor interactions.

Nuclear magnetic resonance studies of the interaction of inhibitors with chymotrypsin. N-Trifluoroacetyl derivatives of phenylalanine

1973 ◽  
Vol 26 (1) ◽  
pp. 135 ◽  
Author(s):  
BC Nicholson ◽  
TM Spotswood
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Chemical Shift ◽  
Magnetic Resonance Spectroscopy ◽  
Active Site ◽  
Molar Ratio ◽  
Resonance Spectroscopy ◽  
Magnetic Resonance Studies ◽  
Derivatives Of ◽  
Nuclear Magnetic

The binding of N-trifluoroacetyl derivatives of phenylalanine to the enzyme chymotrypsin has been studied by 19F nuclear magnetic resonance spectroscopy. Separate resonances are observed for the D- and L- enantiomers in the presence of chymotrypsin and their difference in chemical shift is dependent on the molar ratio of inhibitor to enzyme. The results are interpreted in terms of the known structure of the active site and possible modes of reorientation of the aromatic ring in its binding site. Approximate and accurate methods of quantifying the data are discussed and values for the dissociation constant (KI) of the EI complex, and the change in chemical shift on binding, are reported for the D-isomers.

Nuclear Magnetic Resonance Studies of Phenylthiohydantoin Amino Acids

1975 ◽  
Vol 53 (9) ◽  
pp. 1005-1009 ◽  
Author(s):  
C. S. Tsai ◽  
N. L. Fraser ◽  
H. Avdovich ◽  
J. P. Farant
Keyword(s):  
Amino Acids ◽  
Nuclear Magnetic Resonance ◽  
Amino Acid ◽  
Magnetic Resonance ◽  
Diagnostic Purpose ◽  
Edman Degradation ◽  
Terminal Amino Acid ◽  
Magnetic Resonance Studies ◽  
Terminal Amino ◽  
Derivatives Of

Proton magnetic spectra of 3-phenyl-2-thiohydantoin derivatives of common amino acids in deuterated dimethyl sulfoxide were recorded. Spectral data pertaining to characteristic protons for diagnostic purpose were compiled. Their application to the N-terminal amino acid analysis of peptide by Edman degradation was examined.

Proton nuclear magnetic resonance studies on methylthiohydantoins, thiohydantoins, and hydantoins of amino acids

1977 ◽  
Vol 55 (5) ◽  
pp. 521-527 ◽  
Author(s):  
Tateo Suzuki ◽  
Tetsuhisa Tomioka ◽  
Katura Tuzimura
Keyword(s):  
Amino Acids ◽  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Proton Magnetic Resonance ◽  
Proton Nuclear Magnetic Resonance ◽  
Terminal Amino Acid ◽  
Magnetic Resonance Studies ◽  
Hydantoin Derivatives ◽  
Terminal Amino ◽  
Derivatives Of

Proton magnetic resonance spectra of methylthiohydantoin (3-methyl-2-thiohydantoin), thiohydantoin (2-thiohydantoin), and hydantoin derivatives of amino acids were studied in dimethyl sulfoxide-d6. Their parent amino acids could be identified by the spectra. An application to the N- and C-terminal amino acid analysis of a tripeptide was examined.

19F nuclear magnetic resonance studies of the interaction of inhibitors with chymotrypsin. Derivatives of tryptophan and phenylalanine

1978 ◽  
Vol 31 (10) ◽  
pp. 2167 ◽  
Author(s):  
BC Nicholson ◽  
TM Spotswood
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Least Squares Method ◽  
Competitive Inhibition ◽  
Binding Parameters ◽  
Linear Least Squares ◽  
Magnetic Resonance Studies ◽  
Ph Values ◽  
Derivatives Of ◽  
Tryptophan Derivatives

The binding of the inhibitors N-trifluoroacetyltryptophan, N- trifluoroacetylphenylalanine, N-acetyl-tryptophan and N- acetylphenylalanine to chymotrypsin has been studied by 19F N.M.R. spectroscopy at several pH values. Methods for determining the binding parameters, KI and ΔB, including a model for enzyme oligomerization and competitive inhibition from a second inhibitor, are discussed and a general non-linear least-squares method is presented. Values of KI and ΔB are recorded for D and L enantiomers of tryptophan derivatives and for D-phenylalanine derivatives. The results are discussed in terms of a model for the aromatic binding site of chymotrypsin.

NUCLEAR MAGNETIC RESONANCE STUDIES: IX. THE CHEMICAL SHIFT OF THE FORMYL PROTON IN ALIPHATIC ALDEHYDES

1966 ◽  
Vol 44 (1) ◽  
pp. 45-51 ◽  
Author(s):  
R. E. Klinck ◽  
J. B. Stothers
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Chemical Shift ◽  
Aliphatic Aldehydes ◽  
Magnetic Resonance Studies ◽  
Unsaturated Aldehydes ◽  
Potential Use ◽  
Nuclear Magnetic

The effects of structure on the shielding of formyl protons of aliphatic aldehydes have been examined. The survey included examples of acyclic, alicyclic, and α, β-unsaturated aldehydes. The potential use of these results as an aid for structural elucidations is discussed, and the limitations are noted.

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