Fluorescent aminopyridine derivatives

Periodate-oxidized NADP has been used as an affinity label for other NADP-specific enzymes including pigeon liver malic enzyme (72, 73), spinach ferre-doxin-NADP reductase (74, 75), and Leuconostoc mesenteroides glucose-6-phosphate dehydrogenase (76). Recently, a new fluorescent dialdehyde derivative has been reported as an affinity label of NADP sites, namely, periodate-oxidized 3-aminopyridine adenine dinucleotide phosphate (77). 

In addition, carbohydrates can be derivatized to produce UV or fluorescent species to improve detection. As with the amino acids, both precolumn and postcolumn derivatization are used. Precolumn derivatization influences the chromatographic behavior of the compounds. For UV detection, phenyl-isocyanate derivatization can be used together with RP-HPLC or benzoyl chloride and 4-bromobenzoyl chloride derivatization together with normal-phase chromatography. When fluorescence detection is preferred, dansyl hydrazine and aminopyridine derivatives can be analyzed using RPC. 

The uses of pyridine derivatives, such as aminopyridines, quinaldine, and acridine, together with quaternary salts and photochromic compounds are reviewed in CHEG-II(1996) <1996CHEC-II(5)245>. Pyridinium-based stilba-zolium cationic dyes 43 and 44 were induced to give intense fluorescence by anionic peptide amphiphiles <2006CC1073>. 

Aminopyridine reacts with reducing sugars to form Schiff bases that can be reduced to fluorescent 2-amino-pyridyl derivatives [408], This reaction has been used for the determination of pmol quantities of neutral and amino sugars and of muraminic acid [409]. 

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