Strategies for Site-Specific Radiolabeling of Peptides and Proteins

Although anatomical imaging modalities (X-ray, computed tomography (CT), magnetic resonance imaging (MRI)) still have a higher spatial resolution (0.1–1 mm) than molecular imaging modalities (single-photon emission computed tomography (SPECT), positron emission tomography (PET), optical imaging (OI)), the advantage of molecular imaging is that it can detect molecular and cellular changes at the onset of a disease before it leads to morphological tissue changes, which can be detected by anatomical imaging. During the last decades, noninvasive diagnostic imaging has encountered a rapid growth due to the development of dedicated imaging equipment for preclinical animal studies. In addition, the introduction of multimodality imaging (PET/CT, SPECT/CT, PET/MRI) which combines high-resolution conventional anatomical imaging with high sensitivity of tracer-based molecular imaging techniques has led to successful accomplishments in this exciting field. In this book chapter, we will focus on chemical synthesis techniques for site-specific incorporation of radionuclide chelators. Subsequently, radiolabeling based on complexation of a radionuclide with a chelator will be discussed, with focus on: diethylenetriaminepentaacetic acid (DTPA), 1,4,7,10-tetraazacyclododecane-tetraacetic acid (DOTA), 1,4,7-triazacyclononane-triacetic acid (NOTA), hexa-histidine (His-tag), and 6-hydrazinonicotinic acid (HYNIC) that allow the production of peptides labeled with 18F, 68Ga, 99mTc, and 111In – the currently most widely used isotopes

Bio-orthogonal Imine Chemistry in Chemical Protein Synthesis

Imine chemistry has found multiple applications in the synthesis of highly complex protein targets. In contrast to native chemical ligation methods that will solely result in natural elements, end-products of orthogonal imine chemistry will result in one or more non-natural elements being incorporated in the desired protein target. This chapter will focus on three aspects necessary to employ imine ligation in total protein synthesis. First, functionalization methods are described necessary to introduce carbonyl, aminooxy or hydrazide functionalities in a polypeptide chain. Next, applications of various imine ligation strategies (oxime, hydrazone, Pictet-Spengler) in the field of protein chemistry are reviewed. Finally, methods to catalyse these reactions are summarized

Synthesis and evaluation of peptidic thrombin inhibitors bearing acid-stable sulfotyrosine analogues

Tyrosine sulfation is an important post-translational modification of peptides and proteins which underpins and modulates many protein-protein interactions. In order to overcome the inherent instability of the native modification, we report the synthesis of two sulfonate analogues and their incorporation into two thrombin-inhibiting sulfopeptides. The effective mimicry of these sulfonate analogues for native sulfotyrosine was validated in the context of their thrombin inhibitory activity and binding mode, as determined by X-ray crystallography

A Multi-disciplinary Approach towards the Design and Development of Value+ eHomeCare Services

Do you need spells, magic potions or wizard’s knowledge to approach the eHomeCare market in a successful way? The design and development of eHomeCare services consumes a lot of effort, time and money. Needs and value chain aspects of the eHealth(care) market are complex and sometimes unexpected factors arise during the introduction and first use of technology in the homecare setting. Take up ratios of new products and services are furthermore critical in the return on investment curve. Within this chapter we want to elaborate and share the methodology developed within the IBBT eHomeCare projects Coplintho and TranseCare, used to design and develop ICT related products and services in the homecare field. This implies putting user research up front and working with an interdisciplinary team. This chapter does not claim to offer exhaustive and theoretical knowledge on the subject, but it gives an overview of the practical insights we gained during the passed years. Often references are given for further literature study. Feedback on the subject is greatly encouraged and appreciated

Sulfotyrosine-Mediated Recognition of Human Thrombin by a Tsetse Fly Anticoagulant Mimics Physiological Substrates

Despite possessing only 32 residues, the tsetse thrombin inhibitor (TTI) is among the most potent anticoagulants described, with sub-picomolar inhibitory activity against thrombin. Unexpectedly, TTI isolated from the fly is 2000-fold more active and 180 Da heavier than synthetic and recombinant variants. We predicted the presence of a tyrosine O-sulfate post-translational modification of TTI, prompting us to investigate the effect of the modification on anticoagulant activity. A combination of chemical synthesis and functional assays was used to reveal that sulfation significantly improved the inhibitory activity of TTI against thrombin. Using X-ray crystallography, we show that the N-terminal sulfated segment of TTI binds the basic exosite II of thrombin, establishing interactions similar to those of physiologic substrates, while the C-terminal segment abolishes the catalytic activity of thrombin. This non-canonical mode of inhibition, coupled with its potency and small size, makes TTI an attractive scaffold for the design of novel antithrombotics