SOME FLUORESCENT PROPERTIES OF NONENZYMATIC TRANSAMINATION AND MEASUREMENT OF THE RELATIVE MOLECULAR-MASS OF PROTEIN

A procedure for transaminating proteins and removing the transaminated N-terminal residue has been used for studying structure-function rela tionship of protein (Dixon and Fields 1972, Meth. Enzymol. 25, 409-419 .). We show that it is convenient for measuring the relative molecular masses of proteins by measuring the glycine formed from glyoxylate du ring such transamination. Quinoxaline derivatives have been synthesize d by the reaction of 2-oxo acids from amino acids reading with o-pheny lenediamine. 2-Oxo acids transaminated from amino acids fluoresced at mound 405 nm, depending on the nature of residual side groups. The emi ssion maximum of 3-benzyl-2-hydroxyquinoxaline from the reaction of o- phenylenediamine with phenylpyruvate was at 363 nm The fluorescent der ivatives have been used to study conformational changes of peptides an d to detect whether or not N-termini of proteins ware blocked.