Erwin P P Vos

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During aging, extensive modifications of eye lens proteins take place, which may contribute to the development of cataract. Truncation of the accessible extensions of beta-crystallins has been suggested to be an important factor in this process. We therefore studied the truncations of bovine betaA3- and betaA1-crystallin in more detail. These proteins are(More)
Membrane-bound transport proteins are expected to proceed via different conformational states during the translocation of a solute across the membrane. Tryptophan phosphorescence spectroscopy is one of the most sensitive methods used for detecting conformational changes in proteins. We employed this technique to study substrate-induced conformational(More)
This paper presents domain complementation studies in the mannitol transporter, EIImtl, from Escherichia coli. EIImtl is responsible for the transport and concomitant phosphorylation of mannitol over the cytoplasmic membrane. By using tryptophan-less EIImtl as a basis, each of the four phenylalanines located in the cytoplasmic loop between putative(More)
The mannitol transporter from Escherichia coli, EII(mtl), belongs to a class of membrane proteins coupling the transport of substrates with their chemical modification. EII(mtl) is functional as a homodimer, and it harbors one high affinity mannitol-binding site in the membrane-embedded C domain (IIC(mtl)). To localize this binding site, 19 single(More)
In this work, four single tryptophan (Trp) mutants of the dimeric mannitol transporter of Escherichia coli, EII(mtl), are characterized using Trp and 5-fluoroTrp (5-FTrp) fluorescence spectroscopy. The four positions, 97, 114, 126, and 133, are located in a region shown by recent studies to be involved in the mannitol translocation process. To(More)
This paper presents a tryptophan phosphorescence spectroscopy study on the membrane-bound mannitol transporter, EII(mtl), from E. coli. The protein contains four tryptophans at positions 30, 42, 109, and 117. Phosphorescence decays in buffer at 1 degrees C revealed large variations of the triplet lifetimes of the wild-type protein and four(More)
BACKGROUND Engineering of the yeast Saccharomyces cerevisiae for improved utilization of pentose sugars is vital for cost-efficient cellulosic bioethanol production. Although endogenous hexose transporters (Hxt) can be engineered into specific pentose transporters, they remain subjected to glucose-regulated protein degradation. Therefore, in the absence of(More)
Flow dialysis has found widespread use in determining the dissociation constant (KD) of a protein-ligand interaction or the amount of available binding sites (E0). This method has the potency to measure both these parameters in a single experiment and in this article a method to measure simultaneously the KD and E0 is presented, together with an extensive(More)
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