Three-dimensional structure of echistatin and dynamics of the active site

1994 ◽  
Vol 4 (3) ◽  
Author(s):  
Yuan Chen ◽  
AsifK. Suri ◽  
Dorothea Kominos ◽  
Gautam Sanyal ◽  
AdelM. Naylor ◽  
...  
Keyword(s):  
Active Site ◽  
Three Dimensional ◽  
Dimensional Structure ◽  
Three Dimensional Structure

PREDICTION OF THE THREE-DIMENSIONAL STRUCTURE OF THE ENZYMATIC PART OF T-PA

1987 ◽  
Author(s):  
A Heckel ◽  
K M Hasselbach
Keyword(s):  
Amino Acids ◽  
Amino Acid ◽  
Active Site ◽  
Serine Proteases ◽  
Three Dimensional ◽  
Amino Acid Sequences ◽  
Dimensional Structure ◽  
Salt Bridges ◽  
Three Dimensional Structure ◽  
Insertions And Deletions

Up to now the three-dimensional structure of t-PA or parts of this enzyme is unknown. Using computer graphical methods the spatial structure of the enzymatic part of t-PA is predicted on the hypothesis, the three-dimensional backbone structure of t-PA being similar to that of other serine proteases. The t-PA model was built up in three steps:1) Alignment of the t-PA sequence with other serine proteases. Comparison of enzyme structures available from Brookhaven Protein Data Bank proved elastase as a basis for modeling.2) Exchange of amino acids of elastase differing from the t-PA sequence. The replacement of amino acids was performed such that backbone atoms overlapp completely and side chains superpose as far as possible.3) Modeling of insertions and deletions. To determine the spatial arrangement of insertions and deletions parts of related enzymes such as chymotrypsin or trypsin were used whenever possible. Otherwise additional amino acid sequences were folded to a B-turn at the surface of the proteine, where all insertions or deletions are located. Finally the side chain torsion angles of amino acids were optimised to prevent close contacts of neigh bouring atoms and to improve hydrogen bonds and salt bridges.The resulting model was used to explain binding of arginine 560 of plasminogen to the active site of t-PA. Arginine 560 interacts with Asp 189, Gly 19 3, Ser 19 5 and Ser 214 of t-PA (chymotrypsin numbering). Furthermore interaction of chromo-genic substrate S 2288 with the active site of t-PA was studied. The need for D-configuration of the hydrophobic amino acid at the N-terminus of this tripeptide derivative could be easily explained.

Three-dimensional structure of β-momorcharin at 2.55 Å resolution

1999 ◽  
Vol 55 (6) ◽  
pp. 1144-1151 ◽  
Author(s):  
Yu-Ren Yuan ◽  
Yong-Ning He ◽  
Jian-Ping Xiong ◽  
Zong-Xiang Xia
Keyword(s):  
Active Site ◽  
Structural Model ◽  
Three Dimensional ◽  
Dimensional Structure ◽  
Molecular Replacement ◽  
Ribosome Inactivating Protein ◽  
Three Dimensional Structure ◽  
Replacement Method ◽  
Enzymatic Function ◽  
Molecular Replacement Method

β-Momorcharin (Mr ≃ 29 kDa) is a single-chained ribosome-inactivating protein (RIP) with a branched hexasaccharide bound to Asn51. The crystal structure of β-momorcharin has been determined using the molecular-replacement method and refined to 2.55 Å resolution. The final structural model gave an R factor of 17.2% and root-mean-square deviations of 0.016 Å and 1.76° from ideal bond lengths and bond angles, respectively. β-Momorcharin contains nine α-helices, two 310 helices and three β-sheets, and its overall structure is similar to those of other single-chained RIPs. Residues Tyr70, Tyr109, Glu158 and Arg161 are expected to define the active site of β-momorcharin as an rRNA N-glycosidase. The oligosaccharide is linked to the protein through an N-glycosidic bond, β-GlcNAc–(1-N)-Asn51, and stretches from the surface of the N-terminal domain far from the active site, which suggests that it should not play a role in enzymatic function. The oligosaccharide of each β-momorcharin molecule interacts with the protein through hydrogen bonds, although in the crystals most of these are intermolecular interactions with the protein atoms in an adjacent unit cell. This is the first example of an RIP structure which provides information about the three-dimensional structure and binding site of the oligosaccharide in the active chains of RIPs.

scholarly journals The Three-Dimensional Structure of the Titanium-Centered Active Site during Steady-State Catalytic Epoxidation of Alkenes

2003 ◽  
Vol 107 (8) ◽  
pp. 1932-1932 ◽  
Author(s):  
Gopinathan Sankar ◽  
John Meuring Thomas ◽  
C. Richard A. Catlow ◽  
Carolyn M. Barker ◽  
David Gleeson ◽  
...  
Keyword(s):  
Steady State ◽  
Active Site ◽  
Three Dimensional ◽  
Dimensional Structure ◽  
Three Dimensional Structure ◽  
Catalytic Epoxidation ◽  
Epoxidation Of Alkenes

scholarly journals Enantioselective affinity labelling of horse liver alcohol dehydrogenase. Correlation of inactivation kinetics with the three-dimensional structure of the enzyme

1983 ◽  
Vol 211 (2) ◽  
pp. 391-396 ◽  
Author(s):  
K H Dahl ◽  
H Eklund ◽  
J S McKinley-McKee
Keyword(s):  
Alcohol Dehydrogenase ◽  
Active Site ◽  
Three Dimensional ◽  
Dimensional Structure ◽  
Inactivation Kinetics ◽  
Horse Liver Alcohol Dehydrogenase ◽  
Three Dimensional Structure ◽  
Liver Alcohol Dehydrogenase ◽  
Horse Liver ◽  
Affinity Labelling

Kinetic data for the inactivation of horse liver alcohol dehydrogenase with S-2-chloro-3-(imidazol-5-yl)propionate at pH8.2 were correlated with the three-dimensional structure of the enzyme. The R-2-chloro-3-(imidazol-5-yl)propionate enantiomer did not inactivate the enzyme, and the reaction is thus enantioselective. Inactivation follows an affinity-labelling mechanism where a reversible complex is formed before the irreversible alkylation and inactivation of the enzyme. A reversible complex is also formed with the non-inactivating enantiomer, and this shows that the selectivity occurs at the irreversible step. By using a computer-controlled display system, models of the two enantiomers of 2-chloro- and 2-bromo-3-(imidazol-5-yl)propionate were built into a model of the enzyme so that the imidazole moiety was liganded to the active-site metal, while the carboxylate group interacted with the general anion-binding site. The conformation of the imidazole derivatives and their orientation in the active site were adjusted to minimize unfavourable steric interactions. It was clear that alkylation of cysteine-46 could proceed with the S-enantiomer bound in this way, but not with the R-enantiomer. Model building thus agrees with the inactivation kinetics and indicates the structural origin of the enantioselectivity.

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