The present invention relates to a cycloaddition process comprising the step of reacting a halogenated aliphatic 1,3-dipole compound with a (hetero)cycloalkyne according to Formula (1): Preferably, the (hetero)cycloalkyne according to Formula (1) is a (hetero)cyclooctyne. The invention also relates to the cycloaddition products obtainable by the process according to the invention. The invention further relates to halogenated aliphatic 1,3-dipole compounds, in particular to halogenated aliphatic 1,3-dipole compounds comprising N-acetylgalactosamine-UDP (GalNAc-UDP), and to halogenated 1,3-dipole compounds comprising (peracylated) N-acetylglucosamine (GlcNAc), N-acetylgalactosamine (GalNAc), N-acetylmannosamine (ManNAc) and N-acetyl neuraminic acid (NeuNAc).

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The present invention relates to linker molecules of formula (1), X-T.sub.b-V.sub.aUYZ (1) and a method for purifying peptides using said linker molecules. The linker molecule can be coupled to a purification resin via the moiety X and to a peptide via the moiety Y under the release of the leaving group Z. T is an optional spacer moiety and V is an optional electron withdrawing moiety. U is an aryl or 5- or 6-membered heteroaryl moiety bound to at least one electron withdrawing moiety V, W or E. The linker is stable under acidic conditions and releases the peptide upon addition of a reducing agent.

The present invention relates to linker molecules of formula (1), X-T.sub.b-V.sub.aUYZ (1) and a method for purifying peptides using said linker molecules. The linker molecule can be coupled to a purification resin via the moiety X and to a peptide via the moiety Y under the release of the leaving group Z. T is an optional spacer moiety and V is an optional electron withdrawing moiety. U is an aryl or 5- or 6-membered heteroaryl moiety bound to at least one electron withdrawing moiety V, W or E. The linker is stable under acidic conditions and releases the peptide upon addition of a reducing agent.

The present invention provides compounds according to Formula I as described herein, and their use for inhibiting the lysine gingipain protease (Kgp) from the bacterium Porphyromonas gingivalis. Also described are gingipain activity probe compounds and methods for assaying gingipain activity are also described, as well as methods for the treatment of disorders associated with P. gingivalis infection, including brain disorders such as Alzheimer's disease.

The present invention provides compounds according to Formula I as described herein, and their use for inhibiting the lysine gingipain protease (Kgp) from the bacterium Porphyromonas gingivalis. Also described are gingipain activity probe compounds and methods for assaying gingipain activity are also described, as well as methods for the treatment of disorders associated with P. gingivalis infection, including brain disorders such as Alzheimer's disease.