TY  - JOUR
A1  - Cederkvist, F. Henning
A1  - Zamfir, Alina D.
A1  - Bahrke, Sven
A1  - Eijsink, Vincent G. H.
A1  - Sorlie, Morten
A1  - Peter-Katalinic, Jasna
A1  - Peter, Martin G.
T1  - Identification of a high-affinity-binding oligosaccharide by (+) nanoelectrospray quadrupole time-of-flight tandem mass spectrometry of a noncovalent enzyme-ligand complex
Y1  - 2006
UR  - http://www3.interscience.wiley.com/cgi-bin/jhome/26737/
U6  - https://doi.org/10.1002/anie.200503168
SN  - 1433-7851
ER  - 
TY  - JOUR
A1  - Vaaje-Kolstad, G.
A1  - Houston, Douglas R.
A1  - Rao, F. V.
A1  - Peter, Martin G.
A1  - Synstad, Bjoenar
A1  - van Aalten, Daan M. F.
A1  - Eijsink, Vincent G. H.
T1  - Structure of the D142N mutant of the family 18 chitinase ChiB from Serratia marcescens and its complex with allosamidin
N2  - Catalysis by ChiB, a family 18 chitinase from Serratia marcescens, involves a conformational change of Asp142 which is part of a characteristic D140XD142XE144 sequence motif In the free enzyme Asp142 points towards Asp140, whereas it rotates towards the catalytic acid, Glu144, upon ligand binding. Mutation of Asp142 to Asn reduced k(cat) and affinity for allosamidin, a competitive inhibitor. The X-ray structure of the D142N mutant showed that Asn142 points towards Glu144 in the absence of a ligand. The active site also showed other structural adjustments (Tyr10, Ser93) that had previously been observed in the wild-type enzyme upon substrate binding. The X-ray structure of a complex of D142N with allosamidin, a pseudotrisaccharide competitive inhibitor, was essentially identical to that of the wild-type enzyme in complex with the same compound. Thus, the reduced allosamidin affinity in the mutant is not caused by structural changes but solely by the loss of electrostatic interactions with Asp142. The importance of electrostatics was further confirmed by the pH dependence of catalysis and allosamidin inhibition. The pH-dependent apparent affinities for allosamidin were not correlated with k(cat), indicating that it is probably better to view the inhibitor as a mimic of the oxazolinium ion reaction intermediate than as a transition state analogue. (C) 2003 Elsevier B.V. All rights reserved
Y1  - 2004
SN  - 1570-9639
ER  -