A challenge to the ultrasensitive chemical method for the analysis of oligo- and polysialic acids at a nanogram level of colominic acid and a milligram level of brain tissues

Polysialic acid (polySia) is a functional epitope and is known: 1) to regul ate normal fertilization of lower vertebrates and invertebrates; 2) to be e xpressed on neural cell adhesion molecule (NCAM) when the formation or re-a rrangement of nervous tissues takes place during embryonic stages as well a s in adults of higher vertebrates; and 3) to be re-expressed in several hum an tumors. Thus, polySia serves as oncodevelopmental antigen. To date sensi tive biochemical diagnostic probes (antibodies and endo-N-acylneuraminidase ) to detect polySia are known. However, these reagents are not commercially available yet and they are only reactive to specific types of polySia stru cture. Moreover, precise information not only on diversity but also on the length or degree of polymerization (DP) of extended polySia chains is consi dered important in understanding the molecular mechanism of biosynthesis of polySia chains and fine-tuning of NCAM-NCAM adhesive interaction by polySi a chain but cannot be obtained with these biochemical probes. We have been continuously making efforts to develop and improve the sensitivity of chemi cal methods for polySia analysis toward these challenging problems. This ar ticle presents our most recently developed chemical method for polySia anal ysis and its use in obtaining new information on DP of colominic acid sampl es and polySia chains present in rat brain tissues with the highest sensiti vity that has ever been attained. (C) 2001 Societe francaise de biochimie e t biologie moleculaire / Editions scientifiques et medicales Elsevier SAS. All rights reserved.