The reaction of 4-chloro-7-nitrobenrofurazan (NBD-CI) with 4hydroxy-~ proiine and Lproiine occurs 1 order of magnitude faster than for primary amino acids. In a methanol-buffer medlum, NBD derlvatives are formed partty by reactbn of the amino adds with 4-methoxy-7- nitrobenzofurazan (NBDOCH3) which, In turn, is formed by the reaction of NBD-Ci wtth the solvent. For 1-(7-nitro-4-benzofuraranyi) 4hydroxy-~~ roiine (NBDHyp) fluorescence ...