Pathways and the Physiological Site of Anserine Formation

Abstract

IT is clear from in vivo¹ and in vitro² studies that vertebrate skeletal muscle contains an enzyme that can condense 1-methylhistidine and β-alanine (in the presence of magnesium and adenosine triphosphate) to yield anserine. However, two other paths of anserine biosynthesis have been suggested¹: β-alanyl transfer from carnosine to methylhistidine, and the direct methylation of carnosine. The former possibility has not yet been investigated. The latter alternative is the subject of the present communication. While methyl-labelled methionine was shown to supply effectively the methyl group of anserine^3,4 in vivo it was not evident from such experiments whether N-methylation occurred at the histidine or carnosine stage, nor was the physiological site of anserine formation revealed.