Rob Keller

Charlemagne College, Nijmegen, The Netherlands · Chemistry

The conformational consequences of the interaction of the PhoE signal peptide with bilayers of different types of phospholipids was investigated using circular dichroism. It was found that interaction of the signal peptide with anionic phospholipid vesicles of dioleoylphosphatidylglycerol and dioleoylphosphatidylserine results in induction of high...

The Eisenberg plot or hydrophobic moment plot methodology is one of the most frequently used methods of bioinformatics. Bioinformatics is more and more recognized as a helpful tool in Life Sciences in general, and recent developments in approaches recognizing lipid binding regions in proteins are promising in this respect. In this study a bioinform...

This study aimed to characterise the competitive adsorption behaviour of the different components present in wheat flour and emulsifiers used in breadmaking at an air–water interface using surface balance measurements. It was found that the proteins could be arranged in increasing order of surface activity: albumin < globulin < glutenin < gliadin....

The role of protein-lipid interactions is increasingly recognized to be of importance in numerous biological processes. Bioinformatics is being increasingly used as a helpful tool in studying protein-lipid interactions. Especially recently developed approaches recognizing lipid binding regions in proteins can be implemented. In this study one of th...

This paper was prepared following an invitation to contribute to the inaugural issue of the journal “Lipidology”. Abstract: The precise role of protein-lipid interactions in protein translocation is, after almost four decades of research, still a matter of debate. The experimental evidence, as described in the literature, indicates that (anionic) p...

Article about a journal that has been hijacked multiple times. It appeared on Retraction Watch: Abalkina, A., & Keller, R. (2023). How many times can a journal be hijacked? Retraction Watch. Retrieved from https://retractionwatch.com/2023/02/24/how-many-times-can-a-journal-be-hijacked/

The phenomenon of hijacked journals can be seen as the ultimate example of predatory publishing. Though there are some initiatives to list such sad examples of fraudulent practices it is out of personal experience that from time-to-time new examples 'pop-up'. On numerous occasions, while participating on ResearchGate unfortunate experiences are sha...

In an attempt to estimate the quality of an open access journal the indexing in the Scopus database is often perceived as a positive indicator. While the inclusion in the Beall's list is anticipated as at least a serious warning sign that the journal (or the publisher behind is) might be predatory. On numerous occasions it has been noticed that the...

The data presented here are based on the complete list of predatory journals identified by: Macháček, V., Srholec, M. Predatory publishing in Scopus: evidence on cross-country differences. Scientometrics (2021). https://doi.org/10.1007/s11192-020-03852-4 as was found in 2017. Find enclosed a copy of the supplementary material belonging to the Machá...

Examples of the use of bioinformatics with a focus on biochemistry.

Some thoughts on whether the Beall's list tells you the 'whole' and 'indisputable' story when it comes to alleged predatory journals and publishers. Including a call for more consideration for researchers in this matter.

Adapted version of unpublished chapter of PhD thesis.

Possible help on your way through the internet and all its search engines/databases and so on.

This is the supplement as part of the publication: Keller, R. C. (2015). The role and significance of potential lipid-binding regions in the mitochondrial protein import motor: an in-depth in silico study. 3 Biotech, 5(6), 1041-1051. Included are: additional data and a brief overview of various hydrophobicity scales (see for discussion the indicate...

The results of the search for potential helical lipid binding regions in a number of well-known food proteins is described. All selected food proteins have either well-described or strong indications of protein-lipid interaction features. The results are obtained with the aid of a number of selected bioinformatics tools. The identified potential li...

In an era where sustainability becomes increasingly prominent it is clear that agricultural sources are playing an important role in this goal. Cereal science is a well-established research area when it comes to agricultural and food science related topics. Throughout the years a wealth of information has been gathered when it comes to cereals. Rec...

Over the last two decades, an impressive progress has been made in the identification of novel factors in the translocation machineries of the mitochondrial protein import and their possible roles. The role of lipids and possible protein–lipids interactions remains a relatively unexplored territory. Investigating the role of potential lipid-binding...

The presence of possible lipid-binding regions in the cytoplasmic or extracellular loops of membrane proteins with an emphasis on protein translocation membrane proteins was investigated in this study using bioinformatics. Recent developments in approaches recognizing lipid-binding regions in proteins were found to be promising. In this study a tot...

Thesis as part of obtaining Master of Education degree. At Fontys University Applied Sciences, Tilburg, The Netherlands

Project as part of the program in order to obtain a Master of Education degree. Performed at Applied Sciences University Fontys, Tilburg, the Netherlands.

Protein translocation is an important cellular process. SecA is an essential protein component in the Sec system, as it contains the molecular motor that facilitates protein translocation. In this study, a bioinformatics approach was applied in the search for possible lipid-binding helix regions in protein translocation motor proteins. Novel lipid-...

Reversible physical crosslinks (junction zones) in gelatin gels or films are thought to consist of triple helical collagen-like helices. Using circular dichroism (CD) the structural elements present in gelatin have been studied. The recognition and quantification of the most important conformations in the preparations have been investigated using a...

Poster presentation at various conferences etc.

The testing of new gelatin batches for photographic purposes is a frequently recurring and tedious task that would benefit from efficient new methods for quality assessment. One of the quality parameters is the efficiency of gelation and the stability and strength of the gel and final photographic matrix. The objective of the present IOP-Industrial...

Lecture: An overview was presented of 2-2.5 years of research dedicated to understanding more about the quality parameters of gelatines.

Poster used on various conferences and meetings

Presentation at the Polymer Networks 96 organized by the International Union of Pure and Applied Chemistry Polymer Networks Group in Doorn, the Netherlands, september 2-6, 1996.

Poster presentation at various conferences etc.

Some corrections are indicated (errors in values)

The interactions between a bacterial precursor protein and phospholipids in bilayer-based model membrane systems is addressed in this study. The precursor-lipid interactions were assessed from the side of the lipid phase by fluorescence and electron spin resonance spectroscopy, using the precursor of the Escherichia coli outer membrane protein PhoE...

To investigate in a direct way the interaction between a precursor protein and phospholipids, monolayer studies were performed using the purified precursor of Escherichia coli outer-membrane protein PhoE. It was demonstrated that prePhoE can insert efficiently into monolayers of dioleoylglycerophosphoglycerol (Ole2GroP Gro) and dioleoylglycerophosp...

Reversible physical crosslinks (junction zones) in gelatin gels and films are thought to consist of triple helical collagen-like structures, however other structures may also occur. In an attempt to understand the relation between the material properties and the various junction structures and their abundance, we characterized these structures usin...

In our search for suitable resonance energy transfer (RET) couples for studying protein-lipid interactions, the promising couple coumarin-BODIPY was found and characterized. We characterized the RET from the donor coumarin to two different dipyrrometheneboron difluoride (BODIPY)-labeled phospholipid analogs both experimentally and theoretically. Ca...

The effects of SecA-lipid interactions on lipid mobility were studied by electron spin resonance (ESR) spectroscopy in bilayer systems containing phospholipids spin-labeled at different positions along the acyl chain. The SecA protein, which functions in protein translocation at the cytosolic side of the E. coli inner membrane, was found to decreas...

Preliminary results of a study aimed to characterise the competitive adsorption behaviour of components present in wheat flour as used in breadmaking. Investigations at an air–water interface as studied by surface balance measurements. Final results are presented in: Keller, R. C. A., Orsel, R., & Hamer, R. J. (1997). Competitive adsorption behavio...

Some details (and links to searchable and readable parts) of this thesis about the role of protein-lipid interactions in protein translocation.

Poster presented at various conferences.

Lecture: Data were presented dealing with the role of the signal sequence in protein-lipid interactions and its possible meaning in protein translocation.

SecA which is an overall acidic protein was found to induce an increase in the turbidity of a solution of vesicles consisting of negatively charged phospholipids. This increase was found to be due to an aggregation of the vesicles mediated by SecA. The SecA-mediated vesicle aggregation was not found for zwitterionic 1,2-dioleoyl-sn-glycero-3-phosph...

Poster presentation at various conferences etc.

(Poster) Presentation used for various purposes like: The international symposium on cellular and molecular biology of phosphate and phosphorylated compounds in microorganisms, Wood Hole, Massachusetts, 12-17 September 1993.

In membrane biogenesis and protein targeting, polypeptide chains very often insert into and move across biological membranes. Correct membrane assembly and functioning critically depends on the spatial and temporal interactions between the two main membrane components, i.e. proteins and lipids. It can therefore a priori be reasoned that protein-lip...

Proteins which have to be translocated from the cytosol to another destination in the cell are synthesized with a N-terminal extension, the signal sequence. Although the signal sequence is essential for translocation of a great deal of proteins, its exact role is still unclear. The signal peptide-lipid interaction may be of great importance for the...

Contributed a chapter as co-author to this book: Membrane biogenesis and protein targeting / editors, Walter Neupert and Ronald Lill-(New comprehensive biochemistry ; v. 22) Includes bibliographical references and index. ISBN 0-444-89638-4 1. Membrane proteins-Physiological transport. I. Neupert, Walter. II. Lill, Roland. III. Series. QD415.N48 vol...

The interaction of the signal peptide of the Escherichia coli outer membrane protein PhoE with different phospholipid vesicles was investigated by fluorescence techniques, using a synthetic mutant signal peptide in which valine at position -8 in the hydrophobic sequence was replaced by tryptophan. First it was established that this mutation in the...

The luminescence of nominally pure BaLn2(MoO4)4 (Ln = La,Gd) is reported. Below 300 K molybdate emission is observed. The following activators were investigated: Eu3+, Tb3+, Pb2+ and Bi3+. The two lanthanide ions show their characteristic emission, the two s2 configuration ions give an emission in which the host-lattice group as well as the activat...