Reversible streptavidin based analyte enrichment system for use in crosslinking mass spectrometry analysis

A reversible streptavidin based analyte enrichment system for use in crosslinking mass spectrometry analysis, in particular for enriching at least parts of crosslinked peptides pairs in mass spectrometry analysis, comprising at least one crosslinking agent of the structure of general formulae (I)

• wherein
• R1 is selected from a functional group comprising ester, halogen, aldehyde, isothiocyanate, isocyanate, anhydride, epoxide, acetyl, glyoxal, triazine, hydrazine, disulfide, azide, ketone, phosphine, alkene, amine, N-heterocycle,
• a = 0-10, preferably 1-5, more preferably 2-3;
• Y is selected from —O—, —S—, —S—S—, —S(═O)—, —13CH2—, —CD2—, —18O—m, in particular —O—, —S—, —S—S—;
• n = 0-4, preferably 0, 1 or 2,
• X is selected from a group comprising —N—, —C6H3(NH—), —CH(NH—)—, wherein R2 is attached to N, —CH—, —CH(CO—NH—), wherein R2 is attached to C;
• R2 is one of the structures of formulae (IV) comprising biotin analogues or formulae (V) comprising or desthiobiotin analogues (V), wherein biotin is excluded:
• or
• wherein
• X1, X2, X3 is selected from —NH2, —NH—, —N—Me, —N—Et, —O—.,
• R3 is selected from the group consisting of H, optionally substituted C1-C10 alkyl, optionally substituted C3-C10 cycloalkyl, optionally substituted C2-C10 alkenyl, optionally substituted C3-C10 cycloalkenyl, optionally substituted C2-C10 alkynyl, optionally substituted C2-C10 heteroalkyl, optionally substituted C3-C10 heterocycloalkyl, optionally substituted C2-C10 heteroalkenyl, optionally substituted C3-C10 heterocycloalkenyl, optionally substituted C2-C10 heteroalkynyl, optionally substituted C6-C14 aryl, optionally substituted C5-C14 heteroaryl;
• Z is selected from —CO—, aryl, preferably C5-C6 such as C6-C14 aryl, C5-C14 heteroaryl, alkyl, preferably C1-C4 alkyl, triazoles, alkenes, preferably C2-C4 alkenes, alkyl tetrazines, preferably C1-C4 tetrazines, optionally substituted —CO—NH—(CH2)b—, —CO—NH—(CH2)b—NH—CO—, —CO—NH—(CH2)b—CO—, wherein b = 1-10, preferably 2-6, optionally substituted —CO—NH—(CH2—O—)c—(CH2)d—CO—, CO—NH—(CH2—O—)c—Triazin—(CH2)d—CO—, —CO—NH—(CH2)b—(CH2—O—)c—(CH2)d—NH—CO—(CH2)e—CO— wherein b, c, d, e = 1-10, preferably 2-6.