Galactose oxidase labeling of membrane proteins from human brain white matter

The use of galactose oxidase (EC 1.1.3.9) and tritiated sodium borohydride for labeling of membrane glycoproteins, described by Gahmberg and Hakomori², has previously been applied to the study of myelin glycoproteins of experimental animals⁸. Rat brain myelin glycoproteins have been studied by sequential lectin affinity chromatography¹² and recently the lectin-binding capacity of rat central nervous system myelin glycoproteins has been characterized⁷. Complex heterogeneity of the glycoprotein pattern of rat central nervous system myelin has been reported^7,8,12, and so a variety of glycoproteins can be expected to exist in human white matter membranes. Application of the galactose oxidase procedure to the study of human brain membranes could be useful in research concerning certain neurological diseases if the properties of autopsy brain material are taken into account. In this study, membrane proteins of human autopsy brain white matter were subjected to the galactose oxidase/NaB³H₄ labeling procedure and the membranes labeled by this method or by the ³H]acetic anhydride techniques⁶ were studied by lectin affinity chromatography using Lens culinaris phytohemagglutinin (lentil lectin) attached to Sepharose 4B beads.