Showing papers by "Lutz Schmitt published in 1999"
TL;DR: Recombinant RNAP molecules containing histidine tags (hisRNAP) on the C-terminus were specifically immobilized on ultraflat gold via a mixed monolayer of two different omega-functionalized alkanethiols, which resists protein adsorption and phase-segregate.
65 citations
TL;DR: In this article, the authors investigated a water-soluble version of the murine class II MHC molecule I-Ek complex with an antigenic peptide derived from pigeon cytochrome c residues 89-104 (PCC) by 19F-NMR.
50 citations
TL;DR: The push-off effect may be useful for identifying conformational isomers and for separating them, and is presented that dynA-(1-13) interacts specifically with only one of the two isomeric complexes of PCC-(89-104) and I-Ek.
Abstract: Certain peptides such as dynorphin A [dynA-(1–13)] enhance the release of antigenic peptides bound to class II MHC molecules at neutral pH. This enhanced release has been termed push off. Previous work has shown that the antigenic pigeon cytochrome c peptide PCC-(89–104) has at least two conformational isomers when bound to the class II MHC protein I-Ek. We have accordingly studied the push off of PCC-(89–104) from the complex PCC-(89–104)/I-Ek to see whether these isomeric conformations are distinguished by the push-off effect. A comparison of the association and dissociation kinetics of PCC-(89–104)/I-Ek in the presence of dynA-(1–13) shows that dynA-(1–13) does not simply replace PCC-(89–104) but rather acts catalytically. The major product is peptide-free I-Ek, which is receptive to further peptide binding. Evidence is presented that a two peptide—one MHC complex is formed in solution. This ternary complex represents the first step of the mechanism of push off. 19F NMR data are presented that indicate that dynA-(1–13) interacts specifically with only one of the two isomeric complexes of PCC-(89–104) and I-Ek. A push-off mechanism is proposed in which dynA-(1–13) binds outside the peptide binding groove. In a second step, the dissociation of one of the two isomers is specifically enhanced. Thus the push-off effect may be useful for identifying conformational isomers and for separating them.
25 citations
01 Jan 1999
TL;DR: In this article, the authors studied the push off of PCC-(89-104) from the complex PCC-I-E k to see whether these isomeric conformations are distinguished by the push-off effect.
Abstract: Certain peptides such as dynorphin A (dynA- (1-13)) enhance the release of antigenic peptides bound to class II MHC molecules at neutral pH. This enhanced release has been termed push off. Previous work has shown that the antigenic pigeon cytochrome c peptide PCC-(89-104) has at least two conformational isomers when bound to the class II MHC protein I-E k . We have accordingly studied the push off of PCC-(89-104) from the complex PCC-(89-104)yI-E k to see whether these isomeric conformations are distinguished by the push-off effect. A comparison of the association and dissociation kinetics of PCC-(89-104)yI-E k in the presence of dynA-(1-13) shows that dynA-(1-13) does not simply replace PCC-(89-104) but rather acts catalytically. The major prod- uct is peptide-free I-E k , which is receptive to further peptide binding. Evidence is presented that a two peptide—one MHC complex is formed in solution. This ternary complex repre- sents the first step of the mechanism of push off. 19 F NMR data are presented that indicate that dynA-(1-13) interacts specifically with only one of the two isomeric complexes of PCC-(89-104) and I-E k . A push-off mechanism is proposed in which dynA-(1-13) binds outside the peptide binding groove. In a second step, the dissociation of one of the two isomers is specifically enhanced. Thus the push-off effect may be useful for identifying conformational isomers and for separating them.