Modern Glyoxal Fixation for the Determination of the Copy Number of Synaptic Vesicle Proteins at Individual Synapses

This protocol introduces the use of acid-free glyoxal as a fixative for immunogold localization of proteins. Acid-free glyoxal is a glyoxal solution that was purified from glyoxylic acid. The composition of the presented fixative was created to optimize acid-free glyoxal fixation for increased sensitivity of antibody labeling while preserving the fine structure at the highest possible level. The protocol describes the use of acid-free glyoxal for indirect immunofluorescence and pre-embedding immunogold localization of neuronal antigens.